Animal Sciences Group

Aquaculture and Fisheries Group De Elst 1 6708 WD Wageningen

The Netherlands Tel: +31 (0) 317 483307 Fax: +31 (0) 317 483962

Name: Imke van Gerwen

Reg.nr. 880410259040

MSc Thesis nr. T 1914 THESIS

December 2013

AQUACULTURE AND FISHERIES GROUP

LEERSTOELGROEP AQUACULTUUR EN VISSERIJ

The effects of trap fisheries on the populations of

Caribbean spiny lobster and reef fish species at the

Saba Bank

Abstract:

The Caribbean spiny lobster (Panulirus argus) is a widespread crustacean species. It inhabits shallow

water reefs and rocky substrates from Brazil to Florida. The lobster fishery is one of the most

important fisheries in the Caribbean (in 2011 the total catch was 35,642 tons), generating more than

456 million US dollars annually. However, the annual landings of P. argus throughout the Caribbean

have been in decline since 1995 (FAO, 2013). Over-exploitation is thought to be one of the major

causes of this decline (CRFM, 2011).

One of the areas where the spiny lobster fishery is important, is on the Saba Bank, a 2,200 km2

submerged plateau, near Saba in the northern Caribbean Sea. Spiny lobsters are fished exclusively

with traps by nine small (11m) vessels operating from Saba. To determine the current status of the

P.argus stock and its fishery on the Saba Bank, basic fisheries data were collected in 2012 and

compared with similar studies conducted in 1999 and 2007.

The number of lobster traps hauled per fishing trip increased from 59 to 80 between 1999 and 2012

while the number of lobsters landed per trip decreased from 83 to 52 per trip during the same

period. A similar declined was observed in the standardized (75 trap hauls per trip) CPUE both in

number and total weight of lobster landed. No obvious changes in fishing areas on the Saba Bank

were observed during this period.

The total catch of lobster was estimated as 62 t, 92 t and 38 t in 1999, 2007 and 2012, respectively.

The high catch in 2007 was attributed to the higher number of estimated fishing trips in 2007 (1000)

compared to 1999 (650) and 2012 (600). The lower estimated annual catch in 2012 compared to

1999 is attributed to a decline in CPUE. These result suggest a decrease in abundance of spiny

lobster on the Saba Bank between 1999 and 2012, similar to decline observed in the wider

Caribbean.

Size-at-maturity (CL50%) for male P.argus was found to be 92.2 (± 2.53 SE) mm carapace length,

slightly below the minimum legal size (95mm CL). The mean size of landed male (109 mm CL) and

female lobster (105 mm CL) showed that predominantly large, mature lobster are landed. Berried

female spiny lobsters were observed on the Saba Bank throughout the year with a peak from March

to June.

In addition to lobster, mixed reef fish were also landed in the lobster trap fishery. A total of 57 fish

species were identified in the catches. Roughly 15 kg of mixed reef fish was landed per lobster trip,

resulting in an estimated 8-10 t of mixed reef fish landed in 2012. The species composition (in

weight) of the landed mixed fish consisted mainly of grunts (Haemulon album, H. melanurum and H.

plumierii 30%), small groupers (Epinephelus guttatus and Cephalopholis fulva 17%) and queen trigger

fish (Balistes vetula 21%). Only the mean total length of landed E. guttatus decreased significantly

between 1999 (33 cm TL) and 2012 (31 cm TL).

In addition to the landed mixed fish, an estimated 10 t of mixed fish was discarded in 2012. The

species composition (in weight) of the discarded mixed fish consisted mainly of grunts (H. melanurum

and H. plumierii 34%), boxfishes (Acanthostracion quadricornis and A. polugonia 19%) and nurse

sharks (Ginglymostoma cirratum 9%).

2

Contents

Abstract………………………………………………………………………………………………………………………………………………3

1. Introduction…………………………………………………………………………………………………………………………………4

2. Literature review………………………………………………………………………………………………………………………….7

2.1 Life history and biology of P. argus……………………………………………………………………………………..7

2.1.1 Distribution & abundance………………………………………………………………………………….7

2.1.2 Lobster as a predator………………………………………………………………………………………..7

2.1.3 Lobster as prey………………………………………………………………………………………………….7

2.1.4 Planktonic larval state (phyllosoma)………………………………………………………………….8

2.1.5 Post-larval state (pueruli)………………………………………………………………………………….8

2.1.6 Juvenile state…………………………………………………………………………………………………….9

2.1.7 Adult state………………………………………………………………………………………………………10

2.2 Caribbean P. argus fisheries and management…………………………………………………………………12

2.2.1 Caribbean fisheries………………………………………………………………………………………….12

2.2.2 Population monitoring…………………………………………………………………………………….13

2.3 Biodiversity on the Saba Bank…………………………………………………………………………………………..14

3 Materials & Methods………………………………………………………………………………………………………………….15

3.1 Study site………………………………………………………………………………………………………………………….15

3.2 Study design……………………………………………………………………………………………………………….…….15

3.2.1 Fishing trip log…………………………………………………………………………………………………16

3.2.2 Short interview………………………………………………………………………………………………..17

3.2.3 Long interview…………………………………………………………………………………………………18

3.2.4 On board measuring……………………………………………………………………………….……….18

3.2.5 Carapace length………………………………………………………………………………………………19

3.2.6 Sex…………………………………………………………………………………………………………………..19

3.2.7 Tar spot & Berried females………………………………………………………………………………20

3.2.8 Merus length…………………………………………………………………………………………………..20

3.2.9 Size at maturity males……………………………………………………………………………………..21

3.2.10 Ecdysis…………………………………………………………………………………………………………….21

3.2.11 Mixed fish species composition………………………………………………………………………21

3.2.12 Fork length and Total Length ………………………………………………………………………….21

3.3 Statistical analysis…………………………………………………………………………………………………………….22

3.3.1 Standardization of CPUE………………………………………………………………………………….22

3.3.2 CPUE weight per standardized trip………………………………………………………………….23

3.3.3 Comparing of means……………………………………………………………………………………….23

4 Results……………………………………………………………………………………………………………………………………….24

4.1 Effort………………………………………………………………………………………………………………………………..24

4.2 Catch…………………………………………………………………………………………………………………………………25

4.3 Standardized CPUE……………………………………………………………………………………………………………26

4.4 Length-frequency …………………………………………………………………………………………………………….27

4.4.1 Landed…………………………………………………………………………………………………………….27

4.4.2 Discarded versus landed catch………………………………………………………………………..27

4.5 Reproductive biology.……………………………………………………………………………………………………….30

4.5.1 Females…………………………………………………………………………………………………………..30

3

4.5.2 Males………………………………………………………………………………………………………………30

4.6 Mixed fish…………………………………………………………………………………………………………………………31

4.6.1 Species composition.….……………………………………………………………………………………31

4.6.2 Length-frequency…………………………………………………………………………………………….31

5 Discussion…………………………………………………………………………………………………………………………………..37

5.1 Lobster…………………………………………………………………………..…………………………………………………37

5.1.1 Catch, effort, CPUE………………………………………………………………………………………….37

5.1.2 Length-frequency…………………………………………………………………………………………….38

5.1.3 Reproductive data…………………………………………………………………………………………..39

5.2 Mixed fish…………………………………………………………………………………………………………………………40

6 Conclusion………………………………………………………………………………………………………………………………….42

7 Reference list……………………………………………………………………………………………………………………………..43

Appendix

Acknowledgements

I would like to thank my supervisors Dr. Martin de Graaf and Dr. Leo Nagelkerke for giving me the

opportunity to do this internship and fieldwork on one of the most beautiful places on earth. This

research was financed by BO-11-011-05-008.

I also want to thank the fishermen and deck hands for their cooperation and taking me on board.

Without them I could not have done this research. Special thanks go to: Ivan Hassell, Craig Hassell,

Augustino Hassell, Michelle Peterson, Wes, Julian Hassell, Randall “China” Zeegers, Kenneth Johnson,

Roley Levinstone, Walter Hynds, Nicky Johnson, Ryan Hassell.

Michelle Boonstra, thank you for helping me with my sampling sessions at the harbor.

I would like to thank the Saba Marine Park, Kai Wulf, Gregoor van Laake, and Keith Murphy for

accommodating me and help me with technical issues. Wouter van Looijengoed, thank you for

helping me with the monitoring of the larval collectors.

I am very grateful of Professor Simon de Lestang for helping me with the analysis of the size at

maturity for male P. argus. Last but not least I would like to thank Professor Mark Butler for giving

me advice and lectures on P. argus.

4

0

5000

10000

15000

20000

25000

30000

35000

40000

45000

Cat

che

s (t

)

Fig. 1. Total landings (t) of Panulirus argus in the Caribbean (FAO, 2013)

1. Introduction

The use of marine resources has increased over the past hundred years due to the growth of the

world’s human population and the improvement of technology (Ault et al., 2013; Cadigan, 2001).

Recently the focus on the management of these resources has intensified, due to the decline of fish

stocks and the loss of habitat worldwide (Beddington et al., 2007; Pauly, 2009; Worm et al., 2006; Ye

et al., 2013). One of the marine resources of which catches have decreased over the past decade is

the Caribbean spiny lobster

(Panulirus argus; Latreille, 1804)

(FAO, 2013). In the Caribbean this

species is one of the main

targeted marine resources (CRFM,

2011). Due to increased tourism in

the Caribbean (and specifically the

Dutch Caribbean) the demand for

spiny lobster has risen in the past

decades (Dilrosun, 2000).

However, in 2011 a total of 35,642

tons of lobster have been landed

(FAO, 2013) (fig. 1) which is a

decline of 15 % compared to the

landings of 1995. The decline of

the landings of P. argus is

generally assumed to be caused

by intensified fishery (CRFM,

2011).

The Saba Bank, a large submerged plateau near Saba, is an important fishing ground for the Saban

inhabitants (Dilrosun, 2000; Toller & Lundvall 2008), and has been for the surrounding Islands. Until

the Netherlands Antilles fishery law became effective in 1993, many foreign vessels fished on the

Saba Bank (Guidicelli & Villegas, 1981; Dilrosun, 2000; Hoetjes & Carpenter, 2010). Since the

implementation of the law foreign vessels were prohibited to fish for lobster in the Exclusive

Economic Zone (EEZ) of Saba (Hoetjes & Carpenter, 2010).

Nowadays, the spiny lobster fishery is the most important fishery on the Saba Bank (Lundvall, 2008)

with an estimated ex-vessel revenue of $ 1.3 million US dollar per year (based on total landings of

83600 kg lobster)(Toller & Lundvall, 2008). This is less than 1 % of the total tons of lobster landed in

the Caribbean annually. On Saba, a total of ten fishing licenses are issued to the commercial lobster

fishery (Dilrosun, 2000; Lundvall, 2008) and ca. 30 people generate a living from this fishery

(Dilrosun, 2000).

5

Besides lobster, deep-water snapper species or “redfish” are commonly caught by Saban fishermen.

Because of the difference in fishing method, i.e. different type of bait and traps deployed at greater

depths, this fishery is considered independent (Toller & Lundvall, 2008) and will therefore not be

addressed in this thesis. The Saban fishermen,

fishing for lobster, deploy their traps on shallow

areas of the bank, preferably near rocky substrate or reef structures. These areas are mostly situated

along the edge of the Saba Bank, nearest to the Island of Saba (Toller & Lundvall, 2008). Some

fishermen fish farther on the bank but do not go below depths of 45 meters. This means that 84 % of

the Saba Bank is potentially suitable for lobster fisheries (Toller & Lundvall, 2008). The vast majority

of the catch is sold to the neighbouring Island St. Maarten, the rest of the lobsters is distributed to

other Caribbean islands (Dilrosun, 2000).

The most commonly used trap to catch spiny lobster is the arrowhead trap with a single funnel

(fig.2a+b) (Dilrosun, 2000). The traps are baited with salted cow hides (20 x 20 cm), which are

attached to the traps with coated wires (Toller & Lundvall, 2008). All traps are provided with an

escape panel, a trapdoor on the side of the trap that is fastened with wire, which is both convenient

to get lobsters out of the traps but it is also mandatory.

There are several regulations on the fisheries that are enforced by the Coast Guard to insure

sustainable exploitation of the P. argus population (Dilrosun, 2000). The escape panel, for example,

has to be biodegradable, to minimize the effects of “ghost traps” (Dilrosun, 2000). Another

requirement is that the mesh size of the traps should be no less than 3.8 cm or 1.5 inch (Dilrosun,

2000). Also, it is not allowed to land egg-bearing females or moulting specimen and the minimum

carapace length (CL) of the lobsters is 95 mm (Dilrosun, 2000).

Although the lobster fisheries on the Saba Bank target spiny lobster, it is common that also shallow

water reef fish species are harvested and landed both for commercial benefits and to serve as food

for the spiny lobsters in their holding pots (Toller & Lundvall, 2008). The three fish species that are

Fig. 2a. Arrow head lobster trap. (I van Gerwen 2012).

Escape panel

61

cm

(2

fee

t)

Fig.2b. Arrowhead lobster trap (122x122x61 cm) range of width (91-152 cm),

with a single funnel (w23 x h20 cm) and an escape panel.

6

landed most are: the Haemulon plumierri (White grunt), Balistes vetula (Queen Triggerfish) and

Epinephelus guttatus (Red hind) (Dilrosun, 2000; Toller & Lundvall, 2008). The ex-vessel value of the

total bycatch annually has been estimated at $ 68,700 US dollar (Toller & Lundvall, 2008). Although

this amount is a fraction of the value of landed lobster per year, because of its economic benefits this

bycatch will be quantified. Because of the variety of fish species that are caught the bycatch, both

discarded and landed, will be referred to as “mixed fish” throughout this thesis.

In 2008 a management plan for the Saba Bank was presented. One of the main goals is the

protection and maintenance of biodiversity and natural resources on the Saba Bank (Lundvall, 2008).

To accomplish sustainable use of marine resources on the Saba Bank, long-term monitoring of the

fisheries is essential, to develop target and reference points for indicators, such as catch per unit

effort (CPUE) and average length (Beddington et al., 2007; Lundvall, 2008; Hoetjes & Carpenter,

2010). Two extensive assessments have already been carried out on state of fisheries by Dilrosun

(2000) and Toller & Lundvall (2008). However, compared to other well researched lobster species

stocks i.e. Western rock lobster Panulirus cygnus (Hancock, 1981; De Lestang, 2006; Department of

Fisheries Western Australia, 2013), the quantity of data on the P. argus population on the Saba Bank

is limited. Simple robust quantifiable objectives and reference points are missing. Therefore, the aim

of this study is to obtain data to estimate the current status of the P.argus stock, as well as to provide

a baseline for research in the future. Because the lobster fishery also harvests “mixed fish”, this

research will not only investigate the effects of lobster trap fisheries on the P. argus population, but

it will also investigate the effects on reef fish species.

To reach this goal the following questions will be answered:

- What is the status of the Panulirus argus population on the Saba Bank in 2012 compared to

2000 and 2007?

- What effects do lobster trap fisheries have on both the Panulirus argus population and the

reef fish population on the Saba Bank?

These questions will be addressed by analysing changes in catch per unit of effort (CPUE) of the

fisheries between years and by analysing biologically relevant data such as length frequency, size at

maturity, species composition.

7

2. Literature review

In order to define the status of the Panulirus argus population on the Saba Bank, information is

needed about the biology and factors that influence population dynamics of this species. Therefore,

in this review I am going to treat the life history of P. argus. Also lobster fisheries and management

throughout the Caribbean are covered. At the end I will focus shortly on the Saba Bank for it is the

study site of this research.

2.1 Life history and biology of P. argus

2.1.1 Distribution and abundance

The Caribbean spiny lobster (Panulirus

argus) is an abundant and

widespread, crustacean that belongs

to the order of Decapoda and family

of Palinuridae. The family of

Palinuridae consists of 12 genera

containing 59 species (Zhang, 2011).

Other spiny lobster species which can

be found in the Caribbean are

Panulirus guttatus (Spotted spiny

lobster) and Justitia longimanus (Red

banded lobster) (Humann & Deloach,

2002) Genetic evidence indicates that

P. argus is part of a pan-Caribbean

population, which stretches from

Bermuda to Brazil (Silberman et al.,

1994) (fig. 3). The offshore

distribution of P. argus larvae

contributes to the homogenization

of genetic material throughout the

Caribbean and the recruitment of

lobster stocks in remote areas (Yeung

& McGowan, 1991). This species of

lobster is predominantly found in shallow coastal areas down to depths of 90 m (Holthuis, 1991).

2.1.2 Lobster as predator

Panulirus argus is a predator and its diets changes during ontogeny (Briones-Fourzán et al., 2003; Cox

et al., 2008). In the early juvenile stages (10-15 mm CL) only small and soft prey (1-2 mm in

diameter), are preyed upon (Briones-Fourzán et al., 2003; Cox et al., 2008). During development (15-

44 mm CL) larger and tougher prey is consumed (2-5 mm in diameter). A large overlap in type of prey

is found in the juvenile stages, prey consists mainly of crustaceans and mollusks, such as hermit

crabs, true crabs (Brachyura), and gastropods (Briones-Fourzán et al., 2003; Cox et al., 2008). Besides

the previous mentioned organisms also plant material has been found to be part of juveniles’ diet by

analyzing gut contents (Briones-Fourzán et al., 2003). Prey of late juvenile (45-80 mm CL) stages and

Saba Bank

Fig. 3. Distribution of Panulirus argus. Adjusted after FAO 2013

8

adults consists of crustaceans, echinoderms and mollusks, mainly gastropods but also bivalves and

chitons (Lozano & Alvarez, 1996; Cox et al., 1997; Cox et al., 2008).

2.1.3 Lobster as prey

Natural predators of P.argus are nurse sharks (Ginglymostoma cirratum), triggerfish (Balistidae)

groupers (Serranidae) and other large finfish (Lavalli & Herrnkind, 2009). Also octopuses have found

to prey on P. argus (Berger & Butler et al., 2001). To avoid predation larger juveniles (>15mm CL) and

adult P. argus hide in crevices during the day. At night when the lobsters leave their shelters and they

feel threatened, they swim away by strongly flapping their tail (Humann & deLoach, 2002). Another

defense mechanism is the parrying of predators with their spiny antennae (Lavalli & Herrnkind,

2009). Also the aggregation of adult lobsters into large groups has shown to increase survival rate

(Lavalli & Herrnkind, 2009).

The life history of P. argus can generally be divided in four stages namely the planktonic larval, post-

larval, juvenile, and adult stage. Next the developmental stages will be covered.

2.1.4 Plankton larval stage (Phyllosoma)

Little is known about the planktonic larval stage of P. argus (fig.

4) because the larvae occur in low concentrations far offshore

(Goldstein et al., 2008). In this stage the body of the lobster is

flattened and it has long legs (fig.4) which is appropriately

named phyllosoma meaning “leaf like body”. What is known is

that, the planktonic larval stage undergoes ten metamorphosis

phases (Goldstein et al., 2008; Lewis, 1951). Body lengths of the

phyllosomata range from 1.6 – 27 mm depending on the phase

they are in (Goldstein et al., 2008). Another feature that makes

the research on this developmental stage harder is the duration

of the larval stage. Estimates range from six months to more

than a year (Goldstein et al., 2008; Lewis, 1951; Phillips &

McWilliam, 1986). Also, during the planktonic stage the larvae

migrate vertically through the water column, which adds to the

complexity of the distribution of this developmental stage of P.

argus (Yeung & McGowan, 1991). Taking into account

ontogenetic vertical migration (OVM), diurnal vertical migration

and the long larval stage of P. argus the distance between the

spawning and settlement area of larvae has been estimated to reach up to 400 km (Butler et al.,

2011). The dispersal model also showed a maximum dispersal of approximately 1,000 km. This

indicates that a part of the larvae (~60%) settle close to the adult population; the so called “self –

recruitment” (Butler et al., 2011). The other part (~20%) contributes to long distance dispersal of P.

argus (Butler et al., 2011).

Fig. 4. Phyllosomata of P. argus.(1.6-27mm) (UNC)

9

Post- larval stage (puerulus)

When the planktonic larvae undergo

their last metamorphosis they

transform in a shape that is more

recognisable as an adult spiny lobster

(fig. 5). This stage is called “puerulus”

which means “little boy” with a

carapace length of 5-9 mm (Cox et al.,

2008). The actual metamorphosis

occurs far offshore close to the

continental shelf (Phillips & Williams,

2008). This stage is called puerulus and

only lasts three to four weeks. In this

stage the puerulus does not feed (Cox

et al 2008) and swims towards the shore, mostly on the surface at night during new moon flood tides

to decrease predation pressure (Acosta et al., 1997; Acosta & Butler, 1999). Upon arrival, the pueruli

settle in structurally complex hard-bottom habitats that have abundant, preferably red, macroalgae

vegetation (Marx and Herrnkind, 1985; Herrnkind & Butler, 1986; Field and Butler, 1994). The

physical and chemical cues that the pueruli respond to for the migration into nursery areas are

poorly understood. It is suggested that the metabolites of red algae in nurseries attract the pueruli

and enhance their settlement into coastal habitats (Goldstein & Butler, 2009).

2.1.5 Juvenile stage (10 - ± 80 mm CL)

Approximately 15 days (Goldstein et al., 2008)

after the settlement in the nurseries, the

transparent pueruli of P. argus get more

pigmented and their flattened body shape

transforms into more cylindrical shaped juvenile

stage (fig. 6). Juveniles are solitary living and their

camouflaged bodies blend well in the algal

substrate of the nursery habitat where they stay a

couple of months until they reach 17 mm CL

(Herrnkind & Butler, 1986, Marx & Herrnkind,

1985). Although the juveniles in the nurseries are

sheltered from predators and food is abundant

(Marx & Herrnkind, 1985) mark and recapture

studies show that in the first couple of months only 2-4 % of the settled lobsters survive (Butler et al.,

1997).The mortality rate of the juveniles is negatively related to the number of shelter crevices in the

nursery habitat (Butler et al., 2001). When the juveniles reach a carapace length of 15 mm, they

migrate from the algal vegetation towards the crevices that are mainly provided by sponges where

they reside during daytime (Forcucci et al., 1994, Butler et al., 1995, Herrnkind et al., 1997). During

nighttime these juveniles leave their shelters, where the distance they cover increases with

Fig. 5. Transparent P.argus puerulus. (M. Butler et al., 2010). Size: 5-9 mm CL

Fig. 6. Juvenile of P. argus 12 mm CL (I. van Gerwen 2012)

10

maturation. After one or two years the juveniles leave the nurseries and move towards deeper lying

areas further offshore (Butler et al., 2011).

2.1.6 Adult stage

When the lobsters reach their adult

stage (fig. 7) in 2-3 years (Maxwell et

al., 2013) they change from solitary to

social animals. They more often

aggregate in shelters and with

increasing length natural mortality

declines (Eggleston et al., 1990; Smith

& Herrnkind, 1992), because they have

more effective anti-predator responses

(Briones-Fourzán, 2006). Also the

larger the lobsters grow the less

predators can physically prey upon

them, because the lobsters then do not

fit in their mouths (Nilsson &

Bronmark, 2000). On the other hand

fishing mortality increases with body size (Phillips & Kittaka, 2001). The growth rate of the lobsters

decreases with carapace length (Erhardt, 2008). It is estimated that the lobsters can reach 20 years of

age (Maxwell et al., 2007).

Reproduction

When female and male P. argus reach their adult phase they look for a suitable mating partner. In

pristine ecosystems, the mating system of the Caribbean spiny lobster resembles a lek system, where

one big male has a harem of females and defends his territory (George, 2005). During courting the

males caresses the body of the females with its long legs which enables them to assess the size of the

females (George, 2005). Then the male places a sperm package on the abdomen of the female, which

is called a “tar spot” (George, 2005). The size of the spermatophoric mass (tar spot) that a male

deposits, depends both on the size of the male as well as the size of the female (MacDiarmid &

Butler, 1999). The female produces rows of eggs and keeps them on the ventral side of the abdomen.

She then scratches the sperm package open with her hind legs and transfers the sperm to the eggs.

After the eggs have been fertilized they are retained until they are all ready to hatch. The eggs are all

simultaneously released upon hatching and a cloud of phyllosoma larvae is released into the water

column. Spawning peaks in the spring from March to June (Bertelsen & Mathews, 2001). In areas

closer to the equator it has been found that part of the adult population spawns throughout the year

(Butler et al., 2009). An overview of size at maturity, fecundity and spawning season is found in table

1.)

Fig. 7. An adult male P.argus finds shelter in a crevice (>80 mm CL). (I. van Gerwen

2012)

11

Reproductive characteristic

Reference

Size at maturity –

CL50%

- Female: 86.0±5.1 SD mm CL;

Male: 97.4±5.0 SD mm CL

(Bermuda, UK)

- Female: 81 mm CL (Cuba)

- Female: 93 mm CL (Turks &

Caicos Islands)

- Female: 92 mm CL (Colombia)

- Evans et al. 1995

- Evans et al. 1995

-

- Cruz & Léon, 1991

- Medley & Ninnes, 1997

- Gallo et al., 1998

Fecundity – Clutch size - 0.3 - 0.8 million eggs/clutch

(Florida Keys, FL, USA)

- 147,00 – 1,952,000 eggs/clutch

- Bertelsen & Matthews

2001

- Cox et al. 1997

Spawning season - March – June (Florida, US)

- March-May (Cuba)

- Throughout the year

- Bertelsen & Matthews

2001

- Cruz & Léon, 1991

- Butler et al., 2009

Table 1. Overview of size at maturity, fecundity and spawning season of P.argus in the Caribbean

12

2.2 Caribbean P. argus fisheries and management

2.2.1 Caribbean Fisheries

The P. argus fishery is one of the commercially most important fisheries in the Caribbean.

Throughout the Caribbean P. argus is fished upon with several fishing techniques, ranging from

catching the lobsters by hand by SCUBA divers to hundreds of baited traps hauled by boats that are

equipped with state–of the art devices, such as fish finders, GPS, depth sounder etc. Over 456 million

US dollars are generated with the fisheries on P. argus annually (Ehrhardt, 2005; CRFM, 2011).

Approximately 50,000 lobster fishers are active in the industry, and another 200,000 people that are

working in the lobster fisheries related jobs (FAO, 2003). Brazil, the Bahamas and Cuba are the three

top countries landing most lobsters annually (fig. 8).

The lobsters are sold alive, as a whole, or only the abdomen is frozen or canned (FAO, 2013). With

the industrialization of the fisheries the total landings of the lobsters increased steeply in the

Caribbean from 2,957t in 1950 to 42,519 t in 1996 but then levelled off, and in the past 5-10 years

the landings show a declining trend (FAO, 2013) (fig. 1). This decline has been consistent throughout

the Caribbean and because of the economic importance of this species, it has been stressed that

monitoring and enforcement of regulation is necessary to protect the stocks from overexploitation or

even collapse.

Many P. argus stocks (40%) throughout the Caribbean are considered to be overexploited, 7 out of

18 countries (CRFM, 2011). Therefore, countries have formed management plans and rules and

regulations are enforced locally (appendix A). One common regulatory measure is the closing of the

fishing area for a predetermined amount of months, often coinciding with spawning season. Other

Bahamas 24%

Brazil 21%

Cuba 19%

Nicaragua 12% U.S.A

6% Dominican Republic 4%

Honduras 3%

Mexico 2%

Haiti 2%

Venezuela 2%

Belize 2% Jamaica

1% Colombia 1%

Turks and Caicos Islands

1%

Puerto Rico 0%

Saba 0%

Fig. 8. Top 15 countries harvesting P. argus, as measured by average annual landings from 2000-2007 inclusive and Saba, and the

percentage of the total average landings (34, 664 t) by all countries over the same period of time (adapted from CRFM, 2011)

13

measures are the size limits and restrictions on the landing of moulting or berried females (carrying

eggs). The previously mentioned measures are also in place in the management of the P. argus stock

on the Saba Bank, an area that has not been covered in the CRFM review. However, due to the

aforementioned connectivity of the Caribbean spiny lobster population, management of the stocks is

an international problem. This makes the effectiveness of the management measures difficult to

quantify.

2.2.2 Population monitoring

With artificial collectors (fig. 9), the supply of post-

larvae of several spiny lobster species, have been

monitored (Butler et al. 2010; Gonzalez & Wehrtmann,

2011). By monitoring the recruitment over a longer

period of time (several years) studies have shown that

it is possible to predict stock size and/or catch of the

adult population a couple years later (Hancock, 1981;

Phillips, 1986; Lozano et al.; Cruz et al., 1993). To

predict the stock size of P. argus on the Saba Bank a

recruitment monitoring program was set up at the

coast of the Island Saba, a protocol for the monitoring

is provided in Appendix B.

Fig. 9. Recruitment collector deployed near Saba (I. van

Gerwen, 2012) (60x40x40 cm)

14

2.3 Biodiversity on the Saba Bank

Recently assessments on biodiversity of marine organisms have been performed on the Saba Bank

(Hoetjes & Carpenter, 2010). The Saba Bank is a 2,200 km2 submerged plateau. At the fringes of the

plateau, coral growth is more pronounced. Together with other rocky substrate it forms a habitat

that provides food and shelter for a great variety of marine organisms, including fish and

crustaceans. On this “fore-reef”, the habitat complexity is high, resulting in highest fish biodiversity

(Toller et al., 2010). Further towards the middle of the Bank, the habitat complexity decreases and

with it the biodiversity. In the more shallow parts of the Bank the Caribbean Spiny lobster finds its

habitat. Also large predators are found on the bank, for example nurse and reef sharks, groupers and

barracudas (Williams et al., 2010). During the winter months marine mammals like baleen whales

and several dolphin species are spotted at the edges of the Bank (Lundvall, 2008).

It is suggested that the lack of nursery areas, i.e. sea grass beds or mangroves, and the isolated

location are limiting factors to the fish biodiversity on the Saba Bank (Toller et al., 2010).

Nevertheless, 270 fish species have been recorded on the bank, which is an intermediate number

compared to other studies on reef fish biodiversity (123-517 fish species) (Williams et al., 2010). Also,

45 sponge species, 48 Gorgonian octocoral species and 320 macroalgal species have been

documented (Littler et al., 2010; Williams et al., 2010; Etnoyer et al., 2010; Thacker et al., 2010).

Because the species count did not reach its asymptotic phase, it is expected that the number of these

species on the Saba Bank will even be higher.

Because of this species richness the International Maritime Organization designated the Saba Bank as

the world’s 13th Particular Sensitive Sea Area in 2012. When, in 2010, Saba became part of the Dutch

territory the Saba Bank received the status of an official National Marine Park.

Trap fisheries in the Caribbean have been found to cause over-fishing, biodiversity loss and alteration

of ecosystem structure (Hawkins et al., 2007). Although lobster fisheries mainly target lobsters, with

the traps also shallow water reef fish are caught (Dilrosun, 2000; Toller & Lundvall 2008). Lobster

fisheries have been suggested to affect the biomass distribution of reef fish on the Bank (Toller et al.,

2010). Fish abundance and assemblage on different parts of the Saba Bank was compared based on

reef structure. Biomass and density of reef fish was lower on the fore reef than on reef flat habitat

(Toller et al., 2010). This was not expected because the fore reef was of higher habitat complexity

than the reef flat habitats. Species richness on the Saba Bank, on the other hand, was highest in fore

reef areas (Toller et al., 2010). Fish abundance and diversity has found to be positively correlated

with habitat complexity (Dominici-Arosemana & Wolff, 2005). Other factors that have been found to

affect or have the potential to affect the biodiversity and abundance of organisms on the Saba Bank

are coral bleaching, invasive species i.e. Lion fish; oil spills from neighbouring islands; the loss of traps

due to hurricanes or strong tropical storms; and anchoring of large ships on the Saba Bank (Lundvall,

2008).

15

3. Material and Methods

3.1 Study site

The Saba bank (17025' N, 63030' W) is one of the largest submerged atolls in the world with an

estimated surface area of more than 2,200 km2. It is located 3 – 5 km southwest of the island of Saba

and 25 km West of St. Eustatius (Hoetjes & Carpenter, 2010) (fig. 10). The average depth of the Bank

is 25m, but the shallowest parts in the north and northeast are only 11-13 m deep, from where the

bottom slowly slopes down towards the west. The edges of the bank are quite steep, dropping in

some areas from 11-20m to >500m depth. The term atoll is given to the Saba Bank because of the

presence of corals on the Banks edges creating a reef structure that forms a circle around a lagoon

zone where corals are virtually absent (Toller et al., 2010). The Saba Bank is likely to have a volcanic

core.

3.2 Study design

To determine the status of the P. argus stock on the Saba Bank, catches were monitored over a

fieldwork period of five months (July-November 2012). Basic fisheries catch and effort data was

obtained through standardized short interviews. The catch and effort data was compared to the

assessments of 1999 and 2007. Also, biological data was obtained through sampling of both landed

and discarded catches. This data was collected to estimate the size at maturity and length frequency

of P. argus on the Saba Bank as well as to determine fish species composition and length frequency

Fig. 10. Location of Saba Bank in the Caribbean. (Hoetjes & Carpenter 2010) doi:10.1371/journal.pone.0010769.g001

16

distribution. Monitoring landings alone creates a skewed view on fisheries effects, because in case of

the Saba Bank fishery, a size limit is set for the lobsters landed at the harbour. This will result in a

biased estimate of the selectivity of the traps. Therefore, we decided to quantify discards because

this could give us valuable information on the effect of fisheries on both P. argus and reef fish

populations. With the results of the on-board trips we wanted to validate the importance of discard

monitoring, because the measuring of discards is labour intensive (you have to go on-board, this

takes a day per trip).

The research consisted of both port sampling and on-board sampling of both P. argus and mixed fish

species using the following procedures:

1. Fishing trip log (every day) to collect effort data.

2. Short interviews (66 % of fishing trips) to collect catch and effort data.

3. Long interviews (17.2 % of lobster trips) to collect biological data

4. On-board sampling (9 trips in total) to collect biological data

Lobster

Port sampling On board sampling

Carapace length (CL)

Sex

Tar spot

Merus length (of some male lobsters)

Carapace length (CL)

Sex

Tar spot

Berried

Moulting

Merus length (all discarded male lobsters)

Mixed Fish

Of 27 landed catches and all the discarded catches (9) species composition was recorded. Fish was

identified on the species level. Length data was measured to the nearest cm.

3.2.1 Fishing trip log

In order to obtain a good indication on the fishing intensity and effort on the Saba Bank, every fishing

trip was logged (fig. 11). This meant that every morning the presence or absence of the fishing boats

was monitored. Sometimes fishermen used their boats for purposes other than fishing (i.e. buying

bait or visiting neighbouring Islands). These trips were not logged. On rare occasions fishermen hired

boats (and crew) from other fishermen to haul their traps, because their own boat was out of the

water for repair. In this case the boat that belonged to the owner of the traps was logged instead of

the boat that was hired, this way the trip frequency per boat can be estimated more accurately. An

Table 2. Biological data obtained with “long interviews” at the harbor and with on board sampling

17

average number of trips per day,

for the five months the trips

were logged, was calculated and

extrapolated to average fishing

trips per year, so this could be

compared with previous

assessments. With the short

interviews the percentage of

fishing types (lobster, redfish,

long lining etc.) of the total trips

has been calculated. With the

estimated total fishing trips per

year and the percentage that is

accounted per fishing type the

number of lobster fishing trips

has been calculated.

A total of 377 trips were logged in July-November 2012. Data obtained:

- Number of fishing trips per day

3.2.2 Short interview

The duration of short interviews was approximately 5 min in which fishermen were asked for data

about their trip to obtain basic effort and catch data which we then compared to data from 1999 and

2007. Data included (appendix C):

- number of traps hauled during the trip: effort

- soaking time in days: how long the traps were in the water: effort

- fishing area (quadrant) (fig. 12)

- number of traps lost

- How many lobsters were caught: catch

- if they returned (discarded) any berried females: biological data

- if they returned (discarded) any undersized lobsters: biological data

- how much fish was caught (in lbs. later converted to kg): catch

Additional information for other research

- If they had seen whales or dolphins (not used in this thesis)

- If they discarded lionfish

Fig.11. Typical fishing boat (I. van Gerwen 2012)

18

3.2.3 Long interview

Long interviews were a combination of the short interviews and measuring sessions. First the short

interview was done to obtain basic CPUE data. Then the long measuring sessions were conducted to

obtain biological data to estimate length frequency, size at maturity, reproductive season, species

composition and sex ratio (table 2). Lobster was measured to the nearest mm carapace length, fish

was measured to the nearest cm fork length or total length. Approximately once a week the catch of

each boat was measured during a long interview. In the July-November 2012 a total 44 “long

interviews” were done (incl. 27 fish species composition, 31 lobster (length-frequency/sex/tar spot)

and 13 fish length-frequency data)

3.2.4 On board sampling trips

The biological data obtained with long interviews of the landed catch during port sampling was

expected to be skewed, because legislation prohibits the landing of P. argus with a carapace length

smaller than 95 mm, females that have eggs and individuals that are moulting (ecdysis). Therefore

nine on-board sampling trips were conducted in which the carapace length and sex of discarded

lobsters was determined. Also, females were examined for the presence of a tar spot and/or eggs,

and the merus length of discarded males was measured.

Before the start of the trip the fishermen were asked to divide the catch into discarded and landed

catch during the trip. Because of time constraints, most of the time only the discarded catch was

measured.

Fig. 12. Map of the Saba Bank divided in quadrats.

19

Because mixed fishes attributed a considerable part of the catch, species composition and length

frequency data was also obtained in all on-board sampling (except for one trip) trips and during port

sampling with long interviews.

Biological data collection

Lobster

3.2.5 Carapace length (CL)

The carapace length (CL) of P.argus was measured with a calliper in mm. The outside jaw of the

calliper is placed between the eyes and the inside jaw is placed where carapace ends and the tail

begins (fig. 13a+b).

3.2.6 Sex

The sex of the lobsters can be determined by the hind legs. The ends of the last hind legs of males

Fig. 13b Measuring the carapace length of a male P. argus with a caliper (I. van Gerwen

2012).

Fig. 13a Drawing of carapace length (CL) in detail

(CFR).

Fig. 14. Morphological difference between sexes in P. argus in last walking legs. Left = male (blue),

right = female (pink) (I. van Gerwen, 2012)

♂ ♀

20

are pointed (fig. 14). The ends of the legs of females have extra claws. Other sex specific features

include the presence of a tar spot and/or eggs for (adult) females and the length of the second leg in

(adult) males, which commonly longer than the rest of the legs.

3.2.7 Tar spot & Berried (females)

A tar spot is a sperm package placed by a male on the cephalothorax on the ventral side between the

walking legs of the female (fig. 15) and is an indicator of the maturity of the female. The tar spot is

scratched open to release the sperm and fertilize the eggs. Berried females are females carrying

eggs. To determine the presence of a tar spot and or eggs the female is examined from the ventral

side.

3.2.8 Merus length (males)

In the several crustacean species, i.e. Panulirus cygnus, allometric growth of the second walking leg

(pereiopod) of males has been found to be an indicator for their maturity (Evans et al., 1994;

Fig. 16. Measuring merus length of left walking leg of male P. argus with caliper (I. van Gerwen, 2012)

Fig. 15. Adult female with tar spot and eggs. (I. van Gerwen, 2012)

Tar spot

Eggs

21

Melville-Smith & de Lestang, 2006). Larger males typically have large pereiopods. We measured the

merus of the left side of the male with a calliper to the nearest mm. The calliper was placed behind

the pointed end of the merus and at the beginning of the merus where the isohium ends (fig. 16).

3.2.9 Size at maturity males

The males of P. argus were considered morphometrically mature based on changes in the

relationship between the length of the merus (ML) and the carapace length (CL) as determined by a

regression analysis (Melville-Smith & de Lestang, 2006). First, to test whether the merus length data

actually was allometric, two lines were fitted to the regression ML - CL. With a likelihood ratio test

the appropriateness of using two lines instead of one was tested. When this was determined each

data point was assigned either a 0 (immature) or a 1 (mature) based on their distance from one of

the lines. So if a point was closer to the left hand line then the point was assigned a 0, if it was closer

to the right hand line it was assigned a 1. The two lines were then refitted to these points, so the left

line to all the zeroes and the right line to the ones. Next, all the points were assigned a 0 or 1

according to their distance to either line. This process was iterated 100 times, but stabilized already

after 8 times .The lobsters were then allocated a maturity stage. To determine length when 50% of

the male P.argus is mature a logistic curve was fitted to the data.

3.2.10 Ecdysis

Ecdysis is the moulting of the exoskeleton of crustaceans in order to grow. Moulting animals have a

soft shell and when soft animals were observed they were documented.

Mixed Fish

3.2.11 Mixed fish species composition

Identification of the caught fish species was done based upon the reef fish identification book by

Humann & Deloach (2003). Either all fish species were counted or in some cases the lengths of the

whole catch was measured.

3.2.12 Fork length (FL) and Total Length (TL)

Depending on the fish species either the fork length (FL) was measured or the total length (TL) to the

nearest cm. The species with forked tails like H. melanurum (cottonwick) or Holocentrus rufus

(Longspine squirrelfish) FL was measured as opposed to species like Acanthostracion polygonia

(Honeycomb cowfish) and Chaetodon striatus (Banded butterflyfish) of which the TL was measured.

For the whole list see (appendix D).

22

3.3 Statistical analysis

3.3.1 Standardization of CPUE

Initially the CPUE was expressed as number of lobsters per trip, but because there was a difference in

trap hauls per trip this could influence the variation in CPUE separate from the abundance of

lobsters. The influence of trap hauls per trip could be taken into account by simply expressing the

CPUE as number of lobsters per trip per trap-haul. A simple regression graph where the number of

lobsters per trip was plotted against the number of traps showed a saturation effect of the number

of trap hauls on the number of lobsters being caught per trip (fig. 17). Simply put: the chance of

catching a certain number of lobster per trap-haul diminishes with increased trap-hauls per trip.

Therefore the trips were standardized to take out the “trap-haul” effect. The standardization of the

CPUE was used as described in of Tsehaye et al. (2007).

Other factors that could affect the CPUE, for example boat type or soaking time, were checked for

correlation with a descriptive regression analysis. In case of boat type there was no relation found

with catch per trip, and was therefore not used in the statistical analyses. There was no significant

relationship between soaking time and catch per trip and was not used in the analyses.

Standardisation involved the log-transformation of both the catch data and the effort data. Then the

regression coefficient β was calculated and the standardised CPUE was calculated with the following

formula:

(Tsehaye et al., 2007)

= standardized CPUE

= the mean value for in this case numbers of trap hauled per trip

= the number of traps hauled on trip

Catch data was available for the years 1999, 2000, 2007, 2011 and 2012. Because the data was

obtained in different months and to rule out the possibility of seasonal effects, a GLM was used on

y = 3.534x0.6436 R² = 0.1613

0

50

100

150

200

250

300

0 50 100 150 200 250

No

. Lo

bst

er

pe

r tr

ip

No. Trap-hauls

Fig. 17a +b. Power regression of catch per trip of 1999, 2007 and 2012 in the months July, August, September, October and November

against effort (no. trap hauls). (a) Catch: no. lobster per trip, (b) Catch: No. lobster per standardized trip.

y = 114.44x-0.162 R² = 0.0121

0

50

100

150

200

250

300

0 50 100 150 200 250

No

. Lo

bst

er

pe

r st

and

ard

ize

d

trip

No. Trap-hauls

23

data of the months July, August, September, October and November of the years 1999, 2007 and

2012. Those months were covered in both Dilrosun’s data and data of Toller & Lundvall 2008. Trips

are standardized on 75 trap-hauls per trip.

The calculated standardised CPUE values of the different years were analysed with a GLM with year

as a fixed factor. Since standardized CPUE-values were not normal distributed they were log-

transformed. Post hoc comparisons between years using a Bonferroni correction were performed.

3.3.2 CPUE weight per trip

The weight of male and female lobster was determined using the length weight relationship

determined by Dilrosun (2000). The following formulas were used:

Females: y = 3.3835x2.4724

Males: y =6.1318x2.2234

where x is the carapace length in cm and y the weight in grams. The total weight per trip was

calculated by summing up the individual weights of the lobsters. These estimated weights per trip

were then standardised in the same way as the CPUE no. lobster per trip per trap-haul. Trips were

standardized on 63 trap-hauls per trip.

3.3.3 Comparing of means

Means, standard errors and 95% BCa (Bias corrected and accelerated) confidence intervals were calculated with the use of bootstrapping. This non-parametric test was used to overcome large differences in sample size and the non-normal distribution of the data obtained during on board and port sampling. Bootstraps results came from 1000 bootstrap samples.

24

4. Results

4.1 Effort

During the sampling period 8 (partially) decked fishing boats were active on the Saba Bank. The crew

mainly consisted of the captain and one deckhand (sometimes 2). De boats were powered with

diesel engines; their horsepower ranging from 215 to 600hp (mean 406hp ± 41.7 S.E.). Vessel length

ranged from 30 to 39 ft. (9.14-11.89 m) with a mean of 34.4 ft. ± 1.12 S.E. (10.49m ± 0.34 S.E.). The

tonnage ranged from 5-15 tonnes with a mean of 8.6 tonnes. The fishermen owned a total of 1780

lobster traps, which they deployed on the Saba Bank and checked every 11.6 ± 0.38 S.E. days. These

traps were mainly of arrow head type but some fishermen also used square traps. The size of the

traps differed: 3-4 x 3-5 ft. (0.91-1.22m x 0.91-1.52m). Traps consisted of mesh steel wire, either

galvanized or coated. The size of the mesh in inch: 1x2, 1.5x1.5, 1.5x2, 2x2; in cm: 2.54x5.08,

3.81x3.81, 3.81x5.08, 5.08x5.08.

The fishing areas in 2012 for

lobster fisheries are mainly

situated in the North and East

parts of the Saba Bank (fig. 18).

The total number of trips doubled

from 1999 to 2007 but dropped

with 20% in 2012 based on the

months July-November (table 3).

Interestingly, the percentage of

trips that were lobster trips

decreased with more than 40%

over the time period of 13 years

(table 3). On the other hand the

average number of traps hauled

per trip in 2012 is similar to the

average of 2007. Both are

approximately 30 % more than the average in 1999 (table 3). The average number of trips per day

drops during the weekend in the months July –November in 2012 (appendix E). Due to storms (Isaac

21-28th of August and Raphael 13-16th of October), bad weather or maintenance, boats were out of

the water for several days, sometimes even longer.

Fig. 18. Lobster fishing activities in 2012 at the Saba Bank. Red= high, yellow=

medium, green=low fishing activity.

25

4.2 Catch

With the average weight per lobster in the months July-November and the average number of

lobsters per trip, the total landings of lobsters in kilo is calculated. Striking is that the total lobster

weight per year estimated in 2007 was 50% higher than the total catch in 1999. The total weight then

dropped again in 2012, even lower than 1999, due to decreased number of lobster per trip. The

mean weight per lobster (July-November) differed significantly between the years 1999, 2007 and

2012. Comparing the means with the use of bootstrapping an increase can be seen in weight per

landed lobster from 1999 (1,140.9g ± 482.6 SD, n=10420, BCa 95% CI [1132.11, 1149.42]) to 2007

(1,365g ± 547.9 SD, n=1203, BCa 95% CI [1333.75,1393.18]). The mean in weight per lobster in 2012

(1,217.9g ± 11.8 SD, n=1520, BCa 95% CI [1196.58,1240.54]) is significantly lower than 2007 but

higher than 1999.

Year Mean trip

day-1

SD

Estimated

Total no.

trips per

year

%

Lobster

trips

No. lobster

trips per year

(extrapolated)

Mean no.

traps hauled

per trip &

S.E.

Mean weight

per lobster (g)

& S.E.

Mean no.

Lobster per

trip & S.E.

Total

weight

(kg)

lobster

per year

July-

November

July -

November

July –

November

July-

November

1999 1.8 656 100 656 58.7±2.12 1,140.9±4.7 83.3±5.20 62,362

2007 3.7±2 1,310 76.2 998 80.1±2.78 1,365.4±15.8 69.6±3.72 94,888

2012 2.83±2.01 1,035 58.2 601 79.4±2.64 1,217.9±11.8 52.4±2.28 38,354

Table. 3 Data from short interviews and fishing trip log. Years 1999, 2007 and 2012 are covered.

26

4.3 Standardized CPUE

The regression coefficient of the number of traps in the GLM with the number of lobsters was β =

0.806 and 0.910 for the weight of the lobsters in kg. These values for β indicate an increase of the

catch per trip with the number of traps levelling off in the end. This confirms the saturation effect

mentioned in the materials & methods section. After log transformation of the standardized CPUE

the data was distributed normally. For both the CPUE in no. lobsters per trip and weight of catch per

trip the Levene’s test showed that the homogeneity of variances is equal between the three sampling

years (P>0.05). After standardizing the CPUE the ANOVA shows a significant effect of year on the

number of lobster per standardized trip (F (2, 330) = 36.21, p=<0.005). There was also a significant

effect of year on weight of catch per standardized trip (F (2, 118) = 9.801, p=<0.005). In figure 19 a

decrease can be seen for both standardized CPUE (numbers & weight) from 1999 to 2012. Also the

CPUE for no. lobsters differed significantly between years (p<0.005) in a pairwise test, which was not

the case for the weight per standardized trip where 2007 and 2012 did not differ significantly, as well

as 1999 and 2007. The average numbers of traps that were hauled were 58.7±2.12 SE, 80.1±2.78 SE

and 79.4±2.64 SE (July-November of 1999, 2007 and 2012 respectively).

Fig. 19. Trends in CPUE are expressed as: Mean of No. lobster per standardized trip and weight of total catch per standardized trip.

The total number of observations differed between years, for no. lobster the number of observations were; in 1999 n=80, in 2007

n=101, and in 2012 n=152. The number of observations for weight of catch were; in 1999 n=79, in 2007 n=13, and in 2012 n=26.

Error bars = 95% CI. Mean values of no of lobster per standardized trip a, b and c differ significantly as well as 1 and 2 for weight of

lobster per standardized trip.

0

10

20

30

40

50

60

70

80

90

100

0

10

20

30

40

50

60

70

80

90

100

1998 2000 2002 2004 2006 2008 2010 2012 2014

Cat

ch (

tota

l we

igh

t in

kg)

pe

r st

and

ard

ize

d t

rip

(C

I 95

%)

Cat

ch (

No

. lo

bst

er)

pe

r st

and

ard

ize

d t

rip

(C

I 9

5 %

)

Mean No. Lobsters perstandardized trip

Mean total weight of lobstersper standardized trip

a

b

c

1

1,2 2

27

4.4 Length - frequency

4.4.1 Landed

The mean length of landed lobsters in all years (1999-2000-2007-2011-2012) is at least 10mm above

the legal minimum size of 95 mm. Length-frequency distribution of landed lobsters do not show large

differences between the years 1999, 2007 and 2012 (fig. 21), but means differ significantly between

these three years; mean CL in 1999 106.1mm ± 18.5 SD 95% BCa CI [105.84, 106.32] (n=19478), 2007

111.8mm ± 18.4 SD 95% BCa CI [110.82, 112.76] (n=1518), 2012 107.6mm ± 16.5 SD 95% BCa CI

[106.71, 108.28] (n=1623). Striking is the relative low number of undersized lobster that was landed

in 2011 (4.8% of all the landed lobsters). The landing of undersized lobsters is not uncommon and

although there is a drop in 2011, the overall mean percentage of landed undersized lobsters is 18%

(table 4). Generally more male lobsters are landed than females, except for the year 2011. Length

frequency distribution of male and female lobsters can be found in figure 23. The mean carapace

length differed significantly in the landed catches between sexes; female 105.4 mm ± 16.6 SD 95%

BCa CI [104.03, 106.64] (n=653); male 109.0 mm ±16.3 SD 95% BCa CI [107.94, 110.13] (n=970).

4.4.2 Discarded versus landed catch

The mean length of lobsters differed significantly between landed and discarded catches in 2012. The

mean CL of discarded lobsters is 89.9 mm ± 20.9 SD 95% BCa CI [87.33, 92.34] (n=261) and landed

107.6 mm ± 16.5 SD 95% BCa CI [106.70, 108.44] (n= 1,623). The length- frequency distribution of the

landed and discarded lobsters can be seen in figure 20. In the discards length-frequency distribution

a clear drop is seen at 95 mm CL which is the size that is of which lobsters are allowed to be landed. A

trend can be seen in the discard of undersized lobsters per trip throughout the year. After the

summer months (June-August) the mean number declines then increases again after the winter

months (December-February). In both 2012 and 2013 the highest mean number of discarded

undersized lobsters is in the month of June (fig. 22). In contrast to the landed catches, more female

lobsters were present in the discarded catches; (74.7%).

Year Months Average

CL in mm

standard

deviation

(mm)

N

Undersized

% CL< 95

mm

Undersized

% CL< 90

mm

Female-

male ratio

(%)

1999 APR-NOV 106.1 18.5 19,478 32.3 19.7 39-61

2000 JAN-MAY 110.7 17.8 10,343 18.5 9.4 45- 55

2007 JUN-NOV 111.8 18.4 1,518 16.2 5.9 39-61

2011 OCT-DEC 118.3 15.9 461 4.8 1.1 58-42

2012 MAR-MAY

& JUL-NOV

107.6 16.5 1,623 20 5.7 40-60

Table 4. Length- frequency data of P.argus in landed catches over the years; 1999,2000,2007,2011 and 2012. Months the data is

collected; average carapace length and standard deviation; percentage of undersized lobster CL< 95 mm and CL<90mm; female-

male ratio in percentage.

28

Fig. 21. Length –frequency of landed lobster catches in the years 1999 (April-November), 2007 (June-November) and 2012 (March-

May & July-November)

0

5

10

15

20

25

Fre

qu

en

cy (

%)

Carapace length (mm)

1999, n=19478

2007, n=1518

2012, n=1623

Fig. 20. Length- frequency of P.argus in landed (black) n=1,623 and discarded (striped) n=256 in catches in 2012. Carapace length (CL) in mm and

frequency is number of individual lobsters.

0

5

10

15

20

25

30Fr

eq

ue

ncy

(%

)

Carapace length (mm)

discarded

landed

29

Fig. 23. Length- frequency of P. argus in 2012 for the different sexes n=1,623 in landed catches. CL is in mm and frequency in

number of lobsters (length classes 5mm).

0

50

100

150

200

250

<79 84 89 94 99 104 109 114 119 124 129 134 139 144 149 154 159 164 169 174 179 184 189

Fre

qu

en

cy (

#)

Carapace length (mm)

female

male

Fig. 22. Mean number of undersized lobster discarded per trip. Error bars are 95 %CI March 2012 – August 2013.

0

5

10

15

20

25

30

35

40

45M

ean

no

. un

de

rsiz

ed

lob

ste

rs p

er

trip

(B

Ca

95

% C

I)

30

4.5 Reproductive biology 4.5.1 Females

The mean number of berried female lobsters that was discarded per trip shows an irregular pattern

over months in 2012 and 2013 (fig. 24). In both years the highest mean of discarded berried females

per trip was found in March. Determining size at maturity for females is only possible during the peak

reproductive season, when mature females carry eggs. No peak in mean berried females is seen in

the months July-November. Therefore the analysis of size of maturity in females of data obtained in

the months July- November in 2012 is not accurate (appendix F).

4.5.2 Males

Two lines were fitted in a regression graph was and iterated 8 times until it converged (fig. 25). L50

was estimated at CL =92.2 mm S.E. 2.53 (fig. 25).

Fig. 25. Relationship between the merus length of the second pereiopod and carapace length of immature (black) and mature (red) male P.argus and

logistic regression fitted to the percentage of morphometrically mature males at different carapace lengths.

0

5

10

15

20

25

30

35

Me

an n

o. b

err

ied

fe

mal

es

pe

r tr

ip (

BC

a 9

5%

CI)

Fig 24. Mean number of berried females discarded per trip (error bars BCa 95% CI). March 2012 – August 2013.

31

4.6 Mixed fish

The mean number of landed fish was 50.0 with standard deviation of 51.0 (n=33 trips), the mean

number of discarded fish was 76.1 ± 92.5 SD (n=9 trips). In the discards 41 different species were

discarded as opposed to 49 species that were landed of the total of 57 species that were identified in

all the catches. Eight fish species were only found in discarded catches, especially Diodon

holocanthus, Holocanthus ciliaris and Pomacanthus arcuatus. The maximum number of species

identified in a single landed catch per trip was 22, with a mean of 10 species per catch. On the other

hand, the maximum number of species discarded in a single catch trip was 32 species, with a mean of

13.6 species. With the short interviews, a mean of 12.9 kg fish per landed catch (n=345) was

estimated, the calculation of the average weight per catch per trip of the length-frequency data

showed an average of 15.9 kg. Both estimates were lower than the 17.1 ± 15.5 SD kg per trip

estimated for 2007. The discarded catches contained, with a mean of 17.9 ± 21.2 SD (n=9) kg fish in

2012. More details about the fish species composition in the lobster traps can be found in Appendix

G.

4.6.1 Species composition

The fish species composition differed between landed and discarded catch. Landed fish mainly

consisted of species that were for own consumption (Balistes vetula, parrotfishes) or for commercial

purposes (groupers, grunts etc.) Some fish (Acanthuridae, Pomacanthidae, Ostraciidae etc.) are used

as food for the spiny lobsters in the holding pots. The grouper species (Serranidae) Epinephelus

guttatus (Red Hind) and Cephalopholis fulva (Coney) were almost completely landed as well as

Balistes vetula (Queen Triggerfish). Haemulon plumierii (White Grunt) and Haemulon melanurum

(Cottonwick) were present in high percentages in the landed catch (27% and 8% respectively) (fig.

26a), but were also well represented in the discarded catch (14% and 21%) (fig. 26b). Other fish that

were almost equally found in landings and discards belonged to the Acanthuridae (11.2% discards,

12.3% landed). The fish that belong to the Ostraciidae were more often discarded (23.9 %) than

landed (8.0 %).

Species composition in percentage of total weight sometimes differed from the species composition

in percentage of total number because of size differences between species. For instance, B. vetula

contributes 6% to the total number of landed fish, but 21% to the total weight of the landed catch.

Also the contribution of Ginglymostoma cirratum (Nurse Sharks) to the total weight is higher (9%)

than to the total number fish (1.2%) in the discarded catches. The opposite is seen for Chaetodon

striatus (Banded Butterflyfishes) that contributed more (6.5%) to the total number of fish than to the

total weight (1.7%).

4.6.2 Length-frequency

The length of all the fish in the landed catch is on average higher 26.4 cm ±7.06 SD, n=678 than in the

discarded catch 21.9 cm ±8.06 SD, n=609 (fig. 26e-f). Length-frequency graphs were made of fish

species that were present in both landed and discarded catch; Acanthostracion polygonia

(Honeycomb Cowfish, H. plumierii and H. melanurum. In some species a clear size division is seen

between landed and discarded catches similar to the length-frequency graphs of the total measured

fish. For example, the graph of Acanthostracion polygonia shows a separation between lengths of the

32

catches (fig. 27), in which the smaller individuals are part of discards (22.5 cm ± 2.82 SD, n=87, BCa

95 % CI [21.92, 23.07]) and the larger fishes are landed (25.0 cm ± 2.40 SD, n=50, BCa 95 % CI [24.31,

25.64]) their means differ significantly. On the other hand no clear difference in mean length was

seen in H.melanurum and H. plumierii between landed and discarded catches (Fig. 28 and 29). Still

the mean fork lengths of discarded H. plumierii (23.8 cm ± 2.35 SD, n=96, BCa 95 % CI [23.34, 24.30])

and H. melanurum (21.2 cm ± 2.17 SD, n=124, BCa 95 % CI [20.98, 21.61]) are also significant lower

than the landed fish of these species; H. plumierii: 25.1 cm± 2.24 SD, n= 216, BCa 95 % CI [24.78,

25.39], H. melanurum: 23.1 cm ± 2.45 SD, n=29, BCa 95 % CI [22.58, 24.12].

In the previous assessments the length frequency of the three fish species B. vetula, H.plumierii and

E. guttatus was measured. Compared to the data of 2007, mean length of B. vetula (fig. 30) does not

differ from the mean length 2011-2012, but in both periods significantly larger animals are landed

than in 1999-2000 (1999-2000= 31.7 cm ± 4.59 SD, n=267, BCa 95 % CI [31.18,32.26]; 2007=34.7cm ±

4.78 SD, n=134, BCa 95 % CI [33.95,35.43]; 2011-2012= 34.1cm ± 4.97 SD, n=54, BCa 95 % CI

[32.96,35.51]).

The mean fork length of landed H. plumierii increases significantly over the years (fig. 32) (1999-

2000=23.7cm ± 2.65 SD, n=719, BCa 95 % CI [23.51, 23.94]; 2007= 24.4cm ± 2.96 SD, n=713, BCa 95 %

CI [24.15,24.58]; 2011-2012= 25.1 ± 2.25 SD, n=210, BCa 95 % CI [24.77,25.41]).

Only the mean total lengths of landed E. guttatus (fig. 31) decreased significantly between the years

1999 and 2011-2012 (1999= 33.2cm ± 3.95 SD, n=260, BCa 95 % CI [32.70,33.67]; 2007=32.3cm ±

4.81 SD, n=166, BCa 95 % CI [31.60,32.98]; 2011-2012=31.3 ± 5.11 SD, n=133, BCa 95 % CI

[30.39,32.12]).

33

a. b.

Acanthostracion polygonia

14%

Acanthostracion quadricornis

6%

Acanthurus bahianus

6%

Acanthurus chirurgus

3%

Acanthurus coeruleus

3%

Cheatodon striatus

6%

Chilomycterus antillarum

4%

Haemulon melanurum

21%

Haemulon plumierii

14%

Lactophrys triqueter

3%

other fish 20%

discarded (#)

Acanthostracion polygonia

6%

Acanthurus bahianus

3%

Acanthurus chirurgus

6%

Acanthurus coeruleus

3%

Balistes vetula

6%

Cephalopholis fulva 3%

Epinephelus guttatus

11%

Haemulon melanurum

8%

Haemulon plumierii

27%

other fish 24%

Pseudopeneus maculatus

3%

landed (#)

Acanthostracion polygonia

6%

Acanthurus chirurgus

3%

Balistes vetula 21%

Calamus calamus

2%

Caranx crysos

4%

Cephalopholis fulva 2%

Epinephelus guttatus

15% Haemulon album

7%

Haemulon melanurum

2%

Haemulon plumierii

21%

other fish 17%

landed (weight)

Acanthostracion polygonia

15%

Acanthostracion quadricornis

4%

Acanthurus bahianus

2%

Cantherhines macrocerus

3%

Chilomycterus antillarum

5% Ginglymostoma cirratum

9%

Haemulon melanurum

18%

Haemulon plumierii

16%

Lactophrys triqueter

2%

other fish 24%

Pomacanthus paru 2%

discarded (weight)

0

5

10

15

20

25

30

3 6 9

12

15

18

21

24

27

30

33

36

39

42

>4

2

Fre

qu

en

cy (

%)

FL (cm)

landed

Fig 26(a-f). Pie diagrams a-d depict species compositions in percentages of total nonzero catches. A & b are based on total number of fish

caught, c & d are based on the total weight (kg) of catch. Graphs e & f show length-frequency of total fish in percentages. Graphs a-e are

based on landed catches of 33 trip, c on 17 trips sand b-d-f are based on discarded catches of 9 trips.

e. f.

d. c.

0

5

10

15

20

25

30

3 6 9

12

15

18

21

24

27

30

33

36

39

42

>4

2

Fre

qu

en

cy (

%)

FL (cm)

discarded

34

Fig. 27. Length- frequency of .A polygonia. Frequency is number of fish and length is TL in cm. Catches are divided in landed fish

(black) and discarded fish (striped).

0

5

10

15

20

25

14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

Fre

qu

en

cy (

%)

TL (cm)

A. polygonia

landed

discarded

0

5

10

15

20

25

30

35

12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

Fre

qu

en

cy (

%)

FL (cm)

H. melanurum

landed

discarded

Fig. 28. Length- frequency of H. melanurum. Frequency is number of fish and length is FL in cm. Catches are divided in landed fish

(black) and discarded fish (striped).

0

5

10

15

20

25

16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

Fre

qu

en

cy (

%)

FL (cm)

H. plumierii

landed

discarded

Fig.29. Length- frequency of H.plumierii (2012). Frequency is number of fish and length is FL in cm. Catches are divided in landed fish

(black) and discarded fish (striped).

35

0

5

10

15

20

25

30

21 24 27 30 33 36 39 42 45 48

Fre

qu

en

cy (

%)

FL (cm)

B. vetula

1999-2000, n=267

2007, n=134

2011-2012, n=54

Fig.30. Length- frequency of B. vetula in the periods 1999-2000, 2007 and 2011-2012 of the landed catch. Frequency is percentage of

total caught fish and length is FL in cm.

Fig.31. Length- frequency of E. guttatus in the periods 1999, 2007 and 2011-2012 of the landed catch. Frequency is percentage of

total caught fish and length is TL in cm.

0

5

10

15

20

25

30

21 24 27 30 33 36 39 42 45 48

Fre

qu

en

cy (

%)

TL (cm)

E. gutattus

1999, n=260

2007, n=166

2011-2012, n=133

36

Fig. 32. Length- frequency of H.plumierii in the periods 1999-2000, 2007 and 2011-2012 of landed catch. Frequency is percentage of

total caught fish and length is FL in cm.

0

5

10

15

20

25

30

35

14 16 18 20 22 24 26 28 30 32 34 36 38 40

Fre

qu

en

cy (

%)

TL (cm)

H. plumierii

1999-2000, n=719

2007, n=713

2011-2012, n=210

37

5. Discussion

5.1 Lobster

5.1.1 Catch, effort and CPUE

The striking decrease in annual catch between 2007 and 2012 is in line with the observations of the

annual total lobster catch in Caribbean (CRFM, 2011; FAO, 2013). The decline in annual catch of spiny

lobster on the Saba Bank can be partially be explained by the observed decline in fishing effort.

Fishing effort, expressed as the number of trips per year, has declined on the months July-November

of 1999, 2007 and 2012. Also, the total number of traps used for fishing has declined as well, from

approximately 2,800 lobster traps in 2000, to 2,200 in 2007 and 1,780 lobster traps in 2012.

Remarkably, a shift is seen in target species, in 1999 almost 100% of all fishing trips targeted lobsters.

In 2007 this was already 76% and in 2012 it dropped to 58% of the fishing trips. Thus fishing effort is

shifting more towards “red fish” trap fisheries (Toller & Lundvall, 2008). The reason for this change is

not clear; in other fisheries the choice to shift in target species is attributed to change in market,

revenue, and the decline of target species (Bucaram & Hearn, 2014). In Belize, for example, despite

declining spiny lobster stocks an increase in effort has been documented (Gongora, 2010).

The estimate of annual fishing effort could be an under-estimate, because sampling was done in July-

November which is in the hurricane season. In 2012 several storms passed Saba during these months,

forcing the fishermen to take their boats out of the water. Therefore fewer fishing trips were

undertaken and logged. Extrapolating the mean number of trips per day of these months to estimate

the total trips per year, can therefore result in a lower number of trips than were undertaken in

reality. This can be illustrated with data of Dilrosun (2000). He has logged all the lobster trips

throughout the year from May 1999 to May 2000. In the months July-November 275 trips were

logged. This accounts for an average of 1.8 trips per day, in those months. When extrapolated, this

results in 656 trips for the year 1999. The actual number of lobster trips (May 1999-April 2000) was

731. This means that by extrapolating, we potentially underestimated the total annual number of

trips with 10%. This underestimation influences also the total weight of lobster per year.

The standardized catch per unit effort decreased significantly between the years 1999 - 2012 which is

a strong indication that the abundance of spiny lobsters is declining on the Saba Bank. In 1999 a

mean of 81.9 ± 1.07 S.E. no. of lobsters per standardized trip was caught declining to 60.5 ± 1.06 S.E.

in 2007 and 44.4 ± 1.05 S.E. in 2012. Although the standardized CPUE (in weight per trip) did not

differ significantly between the years 2007 and 2012, the overall trend is that of a declining CPUE,

both in numbers of lobster per trip and weight of catch per trip. These trend in declining of CPUE is

also seen in lobster fisheries in Belize (Gongora, 2010).

Very few similar studies, like this thesis, have been performed on Caribbean spiny lobster populations

throughout the Caribbean (CRFM, 2011). Especially, long-term monitoring datasets on P. argus

fisheries are rare. Still, with the scarce information available, almost all lobster populations

throughout the Caribbean have been said to be either fully or over exploited (CRFM, 2011, appendix

A). Therefore management plans and fishermen mainly focus in reducing effort. Whether the

declining trend in CPUE of lobsters caught on the Saba Bank is caused by the local fishery is not clear.

Other factors, like habitat degradation (Kough et al., 2013; Maxwell et al. 2010), have been said to

cause the decline of P. argus stocks in the Caribbean.

38

One of the factors influencing local P. argus abundance is the connectivity between different

Caribbean spiny lobster stocks (Kough et al. 2013; Silberman et al., 1994). Due to their long larval

state models of Butler et al. (2013) suggest that fisheries from, for example Venezuela and Dominican

Republic, influence the recruitment and thus abundance of P. argus on the Saba Bank. If animals are

caught before they are sexually mature, and have not been able to reproduce, then no larvae will be

taken with the currents and will recruit other areas like the Saba Bank. On the other hand this does

not imply that the P. argus population on the Saba Bank is only dependent on foreign fishery activity

and management. Models (Butler et al., 2011; Butler et al., 2013) show that a large part of the larvae

recruit areas within 400 km of the spawning area. This means that P. argus population at the Saba

Bank is influenced by this “self-recruitment”. Thus to fully understand the lobster fisheries and

changes in catch and effort it is important to incorporate and understand the spatial level of larval

distribution throughout the Caribbean (Kough et al, 2013).

It was difficult to quantify if there was a change in fishing area because of the different methods to

determine fishing area used in previous assessments (Dilrosun, 2000; Toller & Lundvall, 2008). The

quadrants we used differed in size and location from previous assessments. Nonetheless, by visually

comparing the maps of previous assessments with each other, the fishing areas do not seem to have

changed greatly. Only a part of the Saba Bank is fished, due to two reasons. The first is the cost of

fuel. With increasing fuel costs it is not likely that fishing areas will expand further from Saba (Pauly,

2009). This increase in fuel cost might also be the cause of the decrease in fishing effort (total trips

per year) from 1999 to 2012 because the catch is less profitable.

The second reason is that P. argus dwells in shallow waters (Holthuis, 1991) and the shallowest part

with suitable habitat of the Saba Bank is the nearest to the Island of Saba. However, although the

fishing areas have not greatly changed in the past, this does not mean that traps are always dropped

at the same place. Every trip the traps that are hauled are moved a couple of meters (personal

observations). Sometimes all the traps are taken to a new area that has not been fished for a while.

An interesting observation was that when a lobster was caught in a trap there were almost always

more lobsters in the same trap (personal observations). This phenomenon can be explained by the

social behaviour of the lobsters. Adult spiny lobsters tend to aggregate (Lavalli & Herrnkind, 2009).

This mechanism is used in trap fisheries by fishermen were they retain small or undersized lobster in

the traps to attract other, preferably larger lobsters.

5.1.2 Length-frequency

The mean CL of the landed lobsters in 2012 (107.5mm ± 16.5 SD n=1623) on the Saba Bank is large

compared to lobsters caught in the, intensively fished, Florida Keys where lobsters above the size

class 110-119 mm are rarely caught (Maxwell et al., 2010). In the no-take Marine Reserve the Dry

Tortugas larger lobsters are caught. Also, the mean carapace length of landed lobsters from the Saba

Bank is considerably higher than the mean CL of spiny lobsters that are caught in Belize (male:

83.8mm, female: 79.9mm; Gongora, 2010). This difference in mean carapace length can be attributed

by the difference in fishing techniques, lower size limits, but also the status of the local P.argus

population in Belize.

Compared to the size limits for catching P.argus set throughout the Caribbean (minimum catch size

82.55mm, 72.6mm and 95mm CL (CRFM, 2011, appendix A)), the mean CL of the lobsters caught on

39

the Saba Bank suggests that mainly adults are caught that are sexually mature, and that there is thus

an healthy reproductive population on the Saba Bank.

A relative high percentage (20%) of the landed catch in 2012 consisted of undersized lobsters.

However, the percentage of the landed lobsters that are smaller than 90 mm CL is much lower (5.7%)

This is probably because most fishermen estimate the size of the lobster visually (personal

observations). So therefore there could be a measuring error of a few mm. This error is simply

overcome by the use of lobster gauges or callipers. Also, looking at the trend in average number of

undersized lobsters that were discarded in the months July-November, it seems that there is a peak

in the summer. It can be hypothesized that when more undersized lobsters are caught it is more

likely that a higher number will be landed. The mean CL should therefore drop during the summer

months. This can explain the difference in average CL in April-November 1999 (106.1mm ± 18.5 SD)

and mean CL in January-May 2000 (110.7 ± 17.8 SD) (Dilrosun, 2000). The trend seen in number of

undersized lobsters caught and discarded throughout the years 2012 and 2013 can be caused by

changes in water temperature due to seasonality. Juvenile and adult lobsters are known for their

change in mobility depending on sea water temperature (Herrnkind, 1980).

On average more male than female spiny lobsters are landed. Females are discarded more often

because it is not allowed to land females either carrying eggs. Also females are often smaller than

males (George, 2005) and are therefore more likely to be discarded.

5.1.3 Reproductive biology

Berried females were caught throughout the year, but a peak was seen in the spring especially in

March. This finding is consistent with the assessment of Dilrosun (2000), where he also found a peak

in the number of berried females in March on the Saba Bank. In Cuba (Cruz & Leon 1991), Mexico

(Cruz et al., 2001), Florida (Bertelsen & Matthews 2001), and several other areas in the Caribbean

(Ayra & Cruz, 2010) reproduction was highest from March-May. Therefore, if there is a spawning

season of P. argus at the Saba Bank it would be likely to occur in the spring (March-May). However,

spawning of P. argus occurs throughout the year on the Saba Bank, which is common for areas closer

to the equator (Butler et al., 2009). This is probably due to the minimal seasonal temperature

changes as opposed to Florida where a clear spawning period was found in spring (Bertelsen &

Matthews, 2001; Butler et al., 2009).

Calculating size at maturity for females was not possible because the percentage of females that

were sexually mature and had a tar spot was too low. To estimate size at maturity of females I would

recommend repeating the measurements again in March. I expect that the percentage of sexually

mature females with a tar spot to be higher.

The size at maturity for males of 92.2 mm carapace length is just below the size limit of 95 mm.

Therefore, the minimum size can be considered an accurate legislative measure. However, the

importance of large males is overlooked. Large males have the ability to fertilize the eggs of both

small and large females as opposed to smaller males that can only fertilize the whole clutches of

small females (MacDiarmid & Butler 1999). Thus if only small male lobsters remain the full spawning

potential of large females can’t be reached. If the size at maturity of spiny lobsters on the Saba Bank

is representative for the rest of the Caribbean P. argus population, size limits of 82.55mm (i.e.

40

Bahama’s; Turks & Caicos) or 76.2 mm (i.e. Belize) (CRFM, 2011) would probably miss the objective of

ensuring that captured lobsters have had the chance to reproduce.

Although management plans throughout the Caribbean already in place but still little is known about,

fecundity, size at maturity, reproductive season etc. (Ayra & Cruz, 2010). No recent articles are

published on these subjects. I have found only one article published which described a similar

analysis on P. argus to determine the size at maturity of male lobsters (Evans et al. 1995). I would

therefore recommend the investigation of biological parameters i.e. size at maturity throughout the

Caribbean as reference points and to validate management measures.

5.2 Mixed Fish

It is suggested that fisheries on the spiny lobsters can have negative effects on the fish biodiversity

and biomass distribution on the Saba Bank (Toller et al. 2010). Lobster traps catch a variety of reef

fishes in addition to lobsters. In this study it has been found that approximately 20% of the known

fish species on the Saba Bank are caught by the lobster traps. Whether this has a significant effect on

the fish assemblage is discussed below.

Approximately 7800 - 9800 kilo mixed fish caught on the Saba Bank is landed annually. The projected

annual mixed fish landing in 2012 is half of the amount that Toller and Lundvall (2008) estimated in

2008. This can be explained by the decrease in the total fishing trips per year between 2007 and

2012. As for the lobsters, the estimation of the annual mixed fish landing in 2012 could be low

because of the less fishing trips per day in the months July- November compared to the rest of the

year. In addition to the landings a similar amount of mixed fish is discarded. The variation within the

discarded catches was high. There were also many fish species that where both landed and

discarded.

There are several explanations of some fish species being present in both landed and discarded

catches. One reason is size: some small fish are not saleable and are discarded in the hope that they

grow and are caught another time (i.e. H. melanurum conversation fishermen). Another reason is

that there is no demand for those fish at that time (H.melanurum & H. plumierii). Some fishermen

use some species of fish as food for the lobsters in the holding pots (Toller & Lundvall, 2008). Also

some fish species, i.e. Blue tangs or surgeon fishes, that are not marketable, but are normally used

as lobster food are sometimes not taken out of the traps because they have spines and it takes too

long to remove them from the traps (personal observations).

Little research has been done on the by catch of lobster traps in the Caribbean. However, Hawkins et

al. (2007) did look at the effect of trap fishing reef fish communities in the Caribbean. Although they

did not mention the traps being used for lobster fishing, the traps appear similar to the lobster traps

used by the Saban fishermen with the exception of the shape of the funnel entrance. Also similar fish

species were caught with these traps (Hawkins et al. 2007) as with the lobster traps on the Saba

Bank. Hawkins et al. (2007) found that trap fishing on high intensities “…cause serious over-fishing,

reduce biodiversity and alter ecosystem structure”. Although it is difficult to determine the effects of

the lobster trap on the reef fish species on the Saba Bank, the article of Hawkins et al. (2007) makes it

clear that it is important to understand the effects of lobster trap fisheries on the Saba Bank.

41

Only one species (Balistes vetula) that is caught in the lobster traps is listed on the IUCN red list of

endangered species as vulnerable (appendix G). However, the IUCN red list statuses of many of the

fish species that are caught in the lobster traps have not been evaluated yet. Also, if the IUCN list

values a species as “Least Concern” it does not mean that local populations are not threatened.

Therefore, the estimation of effects of lobster traps on reef fish populations has to be done with

caution. Balistes vetula is a species that is both of commercial value for the fishermen, but also is

known to be a P. argus predator (Lavalli & Herrnkind, 2009), which could be the reason they are

always landed when caught. High bodied species that are commonly found in catches like the

butterflyfishes, angelfishes, acanthurids and triggerfishes and which usually have little economic

value are known to benefit from vertical gaps in the traps (Johnson 2010). So they can escape and

unwanted bycatch is prevented.

The lionfish, Pterions volitans is an invasive species from the Indo-Pacific region. It has spread

throughout the Caribbean and has now also populated the Saba Bank. This species is known for its

rapid reproduction rate and because it has venomous spines it has little to no known natural enemies

(Côté et al., 2013), it therefore is important to monitor their presence in the catches because they

could have effects on the banks biodiversity. Compared to data from the red fish fisheries data

(0.65±1.2 SD no. lionfish/trap n=101) (Boonstra, 2013) the catch rate of P. volitans of lobster traps is

low (0.03±0.1 SD no. Lionfish/trap n=158). Because redfish traps are deployed in deeper waters it is

likely that this species has only populated the more deeper areas, perhaps because food is more

available or they are less prone to be predated upon in greater depths.

42

Conclusions The CPUE of spiny lobster has decreased significantly over the course of 13 years,

indicating a decrease in abundance. In 1999 a mean of 81.9 ± 1.07 S.E. no. of lobsters

per standardized trip; 60.5 ± 1.06 S.E. in 2007; 44.4 ± 1.05 S.E. in 2012. Weight of

catch per standardized trip did not differ significantly between the years 1999-2007

and 2007-2012

No apparent changes in fishing areas were observed between 1999 and 2012.

A potential underestimation of 10% of the total annual catch for both lobster and

mixed fish by extrapolating catches of July-November

The number of fishing trips increased between 1999 and 2007 but dropped again in

2012. Fishing trips decreased by 30% between 2007 to 2012.

Spawning of P. argus occurs throughout year, with a peak in March-June.

The mean carapace length of P. argus in landed catches is higher than the size at 50%

maturity estimated for male lobsters (92 ±2.5 SE mm CL) on the Saba Bank.

The mean length of landed male and female lobster suggests that only large, mature

specimens are landed.

Catches of landed mixed fish total in approximately 9800kg annually. It is estimated

that the same amount is discarded. Approximately 20% of known fish species on the

Saba Bank are caught with lobster traps.

43

7. Reference list

Acosta, C.A., Matthews, T.R., Butler IV, M.J. (1997) “Temporal patterns and transport processes in

recruitment of spiny lobster (Panulirus argus) postlarvae to south Florida” Marine biology 129(1): 79-

85

Acosta, C.A., Butler IV, M.J. (1999) “Adaptive Strategies That Reduce Predation on Caribbean Spiny

Lobster Postlarvae During Onshore Transport” Limnology and Oceanography 44(3): 494–501

Ault, J.S., Smith, S.G., Bohnsack, J.A., Luo, J., Zurcher, N., McClellan, N.B., Ziegler, T.A., Halla, D.E.,

Patterson, M., Feeley, M.W., Ruttenberg, B.I., Hunt, J., Kimball, D., Causey, B., (2013) “Assessing coral

reef fish population and community changes in response to marine reserves in the Dry Tortugas,

Florida, USA” Fisheries Research 144: 28– 37

Ayra, L., Cruz, R., (2010) “Caribbean lobster reproduction: a review” Revista de Investigaciones

Marinas 31(2): 115-123

Beddington, J.R., Agnew, D.J., Clark, C.W., (2007) “Current problems in the management of marine

fisheries” Science 316: 1713-1716

Berger, D.K., Butler IV, M.J. (2001) “Octopuses influence den selection by juvenile Caribbean spiny

lobster” Marine Freshwater Research 52:1049–53

Bertelsen, R.D., Matthews, T.R., (2001) “Fecundity dynamics of female spiny lobster (Panulirus argus)

in a south Florida fishery and Dry Tortugas National Park lobster sanctuary” Marine Freshwater

Research 52: 1559–65

Briones-Fourzán, P., Pérez-Ortiz, M., Lozano-Álvarez, E. (2006) “Defense mechanisms and

antipredator behavior in two sympatric species of spiny lobsters, Panulirus argus and P. guttatus”

Marine Biology 149: 227–239

Bucaram, S.J., Hearn, A. (2014) “Factors that influence the entry–exit decision and intensity of

participation of fishing fleet for the Galapagos lobster fishery” Marine Policy 43:80–88

Butler, M.J. IV, Herrnkind, W. F., Hunt, J.H., 1997. “Factors affecting the recruitment of

juvenile Caribbean spiny lobsters dwelling in macroalgae” Bulletin Marine Science 61: 3-19

Butler IV, M.J., Hunt, J.H., Herrnkind, W.F., Childress, M.J., Mertelsen, R., Sharp, W., Matthews, T.,

Field, J.M., Marshall, H.G. (1995) “Cascading disturbances in Florida Bay, USA: cyanobacteria blooms,

sponge mortality, and implications for juvenile spiny lobsters Panulirus argus” Marine ecology

progress series 129:119-125

Butler., M.J., Mojica, A.M., Sosa-Cordero, E., Millet, M., Sanchez-Navarro, P., Maldonado,

M.A.,Posada, J., Rodriguez, B., Rivas, C.M., Oviedo, A., Arrone, M., Prada, M., Bach, N., Jimenez, N.,

Del Carmen Garcia-Rivas, M., Forman, K., Behringer, Jr. D.C., Matthews, T., Paris, C., Cowen, R.,(2010)

44

“Patterns of Spiny Lobster (Panulirus argus) Postlarval Recruitment in the Caribbean: A CRTR Project”

GCFI: 62

Butler IV, M. J., Paris, C.B., Goldstein, J. S., Matsuda, H., Cowen, R. K. (2011) “Behavior constrains the

dispersal of long-lived spiny lobster larvae” Marine ecology progress series 422: 223–237

Briones-Fourzán, P., Castañeda-Fernández de Lara, V., Lozano-Álvarez, E., Estrada-Olivo, J., (2003)

“Feeding ecology of the three juvenile phases of the spiny lobster Panulirus argus in a tropical reef

lagoon” Marine Biology 142, 855–865.

Cadigan, S. (2001) “Whose fish? Science, ecosystems and ethics in fisheries management literature

since 1992” Acadiensis 31(1): 171–195

Côté, I.M., Green, S.J., Hixon, M.A., (2013) “Predatory fish invaders: Insights from Indo-Pacific

lionfishin the western Atlantic and Caribbean” Biological Conservation 164: 50–61

Cox, S.L., Jeffs, A.G., Davis M. (2008) “Developmental changes in the mouthparts of juvenile

Caribbean spiny lobster, Panulirus argus: Implications for aquaculture” Aquaculture 283: 168–174

Cox, C., Hunt, J.H., Lyons, W.G., Davis, G.E. (1997) “Nocturnal foraging of the Caribbean spiny lobster

(Panulirus argus) on offshore reefs of Florida, USA” Marine and Freshwater Research 48(8): 671 - 680

CRFM, 2011. Baseline Review of the Status and Management of the Caribbean Spiny Lobster Fisheries

in the CARICOM Region. CRFM Technical & Advisory Document, No. 2011/ 5. 64p.

Cruz, R., de León, M. E., (1991) Dinámica reproductiva de la langosta (Panulirus argus) en el

archipiélago cubano. Revista de Investigaciones Marinas 12 (1-3): 234-245

Cruz, R., De León, M. E., Puga, R., (1993) Prediction of commercial catches of the spiny lobster

Panulirus argus in the gulf of Batabanó, Cuba. Proceedings of the Fourth International Workshop on

Lobster Biology and Management,

Department of Fisheries Western Australia http://www.fish.wa.gov.au/Species/Rock-

Lobster/Lobster-Management/Pages/Puerulus-Settlement-Index.aspx

Photos/figures

Dilrosun, F. 2000. Monitoring the Saba Bank fishery. Department of Public Health and Environmental

Hygiene, Environmental Division. Curaçao, Netherlands Antilles.

Eggleston, D., Lipcius, R., Coba-Centina, L., Miller D., (1990) “Shelter scaling regulates survival of

juvenile spiny lobster, Panulirus argus” Marine Ecology Progress Series 62:79–88.

Ehrhardt, N.M., (2008) Estimating growth of the Florida spiny lobster, Panulirus argus, from molt

frequency and size increment data derived from tag and recapture experiments” Fisheries research

93: 332-337

45

Ehrhardt, N.M., Deleveaux (2009) “Fishing capacity in a trap fishery for Panulirus argus” Fisheries

Bulletin 107:186–194

Etnoyer, P.J., Wirshing, H.H., Sánchez, J.A. (2010) “Rapid Assessment of Octocoral Diversity and

Habitat on Saba Bank, Netherlands Antilles” PLoS ONE 5 (5):

e10668.doi:10.1371/journal.pone.0010668

Evans, C.R., Evans, A.J. (1995) “Fisheries ecology of spiny lobsters Panulirus argus (Latreille) and

Panulirus guttatus (Latreille) on the Bermuda Platform: estimates of sustainable yields and

observations on trends in abundance” Research 24: 113-128

Evans, C.R., Lockwood, A.P.M, Evans, A.J., Free, E., (1995) “Field studies of the reproductive biology of

the spiny lobster Panulirus argus (Latreille) and P. gutattus (Latreille) at Bermuda” Journal of Shellfish

Research 14(2): 371-381.

FAO 2013

http://www.fao.org/figis/servlet/SQServlet?ds=Capture&k1=SPECIES&k1v=1&k1s=3445&outtype=ht

ml

Field, J.M. and Butler IV, M.J. (1994) “The influence of temperature, salinity, and postlarval transport

on the distribution of juvenile spiny lobsters, Panulirus argus (LATREILLE, 1804), in Florida bay”

Crustaceana 67 (1): 26-44

Forcucci, D., Butler, M. J., Hunt, J.H., (1994) “Population dynamics of juvenile Caribbean spiny lobster,

Panulirus argus, in Florida Bay, Florida” Bulletin of marine science, 54(3): 805-818

Gallo, K., Rojas, M., Correa, F., (1998) “Aspectos sobre la biología y pescerías de la langosta Espinosa

(Panulirus argus) en la República de Colombia” Workshop on the Spiny Lobster Panulirus argus in the

WECAFC area. Reporte Nacional de Colombia. 18 p

Gongora, M. (2010). Assessment of the Spiny Lobster (Panulirus argus) of Belize Based on Fishery-

Dependent Data. Belize Fisheries Department. Marine Fisheries Insititute.

Johnson, A. E. (2010) “Reducing bycatch in coral reef trap fisheries: escape gaps as a step towards

sustainability” Marine ecology progress series 415: 201–209

George, R.W. (2005) “Comparative morphology and evolution of the reproductive structures in spiny

lobsters, Panulirus” New Zealand Journal of Marine and Freshwater Research 39: 493-501

Goldstein, J.S., and Butler, M.J., IV (2009) “Behavioral Enhancement of Onshore Transport by

Postlarval Caribbean Spiny Lobster (Panulirus Argus)” Limnology and Oceanography 54 (5):1669–

1678

Goldstein, J.S., Matsuda, H., Takenouchi, T., Butler, M.J. IV (2008) “The complete development of

larval Caribbean spiny lobster, Panulirus argus, in culture” Journal of Crustacean Biology 28: 306–327

46

González, O., Wehrtmann, I.S. (2011) “Postlarval settlement of spiny lobster, Panulirus argus

(Latreille, 1804) (Decapoda: Palinuridae), at the Caribbean coast of Costa Rica” Latin American

Journal Aquatic Research 39(3): 575-583

Guidicelli, M., Villegas, L., (1981) Program for fisheries development in Saba and St. Eustatius

Interregional Fisheries Development and Management Program FAO United Nations, WECAF

Rep, 39

IUCN, 2012. IUCN Red List of Threatened Species. Version 2012.1. IUCN 2012. IUCN Red List of

Threatened Species. Downloaded in June 2013.

Hawkins, J.P., Roberts, C.M., Gell, F. R. and Dytham, C. (2007) “Effects of trap fishing on reef fish

communities” Aquatic conservation: Marine and freshwater ecosystems 17: 111–132

Hancock, D.A., (1981) Research for management of the Rock lobster fishery of Western Australia.

Herrnkind, W. F. (1980) “Spiny lobsters: patterns of movement. The biology and management of

lobsters. Volume I. Physiology and behavior” Academic Press, New York, New York, USA. Pages 349–

407 in J. S. Cobb and B. F. Phillips, editors

Herrnkind W.F. Butler IV, M. J. (1986) “Factors regulating postlarval settlement and juvenile

microhabitat use by spiny lobsters Panulirus argus” Marine ecology – progress series 34: 23-30

Herrnkind, W. F., Butler IV, M. J., Hunt, J. H. and Childress M. (1997) “Role of physical refugia:

implications from a mass sponge die-off in a lobster nursery in Florida” Marine and Freshwater

Research 48(8) 759 - 770

Hoetjes P.C., Carpenter K.E. (2010) Saving Saba Bank: Policy Implications of Biodiversity Studies. PLoS

ONE 5(5): e10769. doi:10.1371/journal.pone.0010769

Holthuis, L.B., FAO species catalogue. Vol. 13. Marine lobsters of the world. An annotated and

illustrated catalogue of species of interest to fisheries known to date, FAO Fisheries Synopsis. No. 125,

Vol. 13. Rome, FAO. 1991. 292 p

Humann, P., deLoach, N. (2002) Reef creature identification: Florida, Caribbean, Bahamas. New world

publications, second edition.

Humann, P., deLoach, N. (2003) Reef fish identification: Florida, Caribbean, Bahamas. New world

publications, third enlarged edition.

Van der Land, J. (1977) The Saba Bank – a large atoll in the northeastern Caribbean. FAO Fisheries

Report 200: 469-481.

47

Lavalli ,K.L., Herrnkind, W.F., (2009) “Collective defense by spiny lobster (Panulirus argus) against

triggerfish (Balistes capriscus): effects of number of attackers and defenders” New Zealand Journal of

Marine and Freshwater Research (43): 15-28

Lozano, E., P. Briones & B.F. Phillips (1991) “Fishery characteristics, growth, and movements of the

spiny lobster Panulirus argus in Bahía de la Ascension, Mexico” Fisheries Bulletin 89: 79-89

Lozano-Alvarez, E., and Spanier, E. (1997) “Behaviour and growth of captive spiny lobsters (Panulirus

argus) under the risk of predation” Marine and Freshwater Research 48(8) 707 - 714

Lewis, J.B. (1951) “The phyllosoma larvae of the spiny lobster Panulirus argus” Bulletin of marine

science 1(2): 89-103

Lewis, C.F., Slade, C.L., Maxwell, K. E., Matthews, T.R. (2009) “Lobster trap impact on coral reefs:

effects of wind-driven trap movement” New Zealand Journal of Marine and Freshwater Research, 43:

271-282

Littler, M.M., Littler, D.S., Brooks, B.L. (2010) Marine Macroalgal Diversity Assessment of Saba Bank,

Netherlands Antilles. PLoS ONE 5(5): e10677. doi:10.1371/journal.pone.0010677

Lundvall S. (2008) Saba Bank, Special Marine Area Management Plan. Department of Public Health

and Social Development, Department of Environment and Nature, Willemstad.

MacDiarmid, B., and Butler IV, M. J. (1999) “Sperm economy and limitation in spiny lobsters”

Behavioral Ecology and Sociobiology 46: 14-24

Marx J. M., and Herrnkind, W. F. (1985) “Macroalgae (rhodophyta: Laurencia spp.) as habitat for

young juvenile spiny lobsters, Panulirus argus” Bulletin of marine science 36(3): 423-431

Maxwell, K. E., Matthews, T.R., Bertelsen R.D., Derby, C. D. (2009) “Using age to evaluate reproduction in Caribbean spiny lobster, Panulirus argus, in the Florida Keys and Dry Tortugas, United States” New Zealand Journal of Marine and Freshwater Research 43(1): 139-149 Maxwell, K.E., Matthews, T.R., Bertelsen, R.D., Derby, C.D., (2013) “Age and size structure of Caribbean spiny lobster, Panulirus argus, in a no-take marine reserve in the Florida Keys, USA” Fisheries Research 144: 84– 90

Maxwell, K.E., Matthews, T.R., Sheehy, M.R.J., Bertelsen, R.D., Derby, C.D., (2007) “Neurolipofuscin is

a measure of age in the Caribbean spiny lobster, Panulirus argus, in Florida” Biological Bulletin 213:

55–66

Medley, P.A.H. & Ninnes, C.H. (1997) “A recruitment index and population model for spiny lobster

(Panulirus argus) using catch and effort data” Canadian Journal of Fisheries and Aquatic Sciences 54:

1414-1421

48

Melville-Smith, G.R., De Lestang, S. (2006) “Spatial and temporal variation in the size at maturity of

the western rock lobster Panulirus cygnus” Marine Biology 150:183–195

Metcalf, S. J., Pember, M.B., and Bellchambers, L.M. (2011) “Identifying indicators of the effects of

fishing using alternative models, uncertainty, and aggregation error” ICES Journal of Marine Science

68, no. 7: 1417–1425.

van Oostenbrugge, J.A.E., Bakker, E.J., van Densen, W.L.T., Machiels, M.A.M., and van Zwieten,

P.A.M. (2002) “Characterizing catch variability in a multispecies fishery: implications for fishery

management Canadian Journal Fisheries and Aquaculture Science 59: 1032–1043

Nilsson, P.A., Brönmark, C., (2000) “Prey vulnerability to a gape-size limited predator: behavioural

and morphological impacts on northern pike piscivory” Oikos 88:539-546.

Pauly, D., (2009) “Beyond duplicity and ignorance in global fisheries” Scientia Marina 73(2): 215-224

Phillips, B.F., McWilliam, P.S. (2008) “Spiny Lobster Development: Where Does Successful

Metamorphosis to the Puerulus Occur?: a Review.” Reviews in Fish Biology and Fisheries 19(2): 193–

215.

Phillips, B.F., McWilliam, P.S. (1986) “The pelagic phase of spiny lobster development” Canadian

Journal of Fisheries and Aquatic Sciences 43: 2153– 2163

Phillips, B.F. (1986) “Prediction of commercial catches of the western rock lobster Panulirus Cygnus”

Canadian Journal Fisheries and Aquaculture 43: 2126-2130

Puga, R., Estela de León, M., Cruz, R. (1996) “Catchability for the main fishing methods in the Cuban

fishery of the spiny lobster Panulirus argus (Latreille, 1804), and implications for management

(decapoda, palinuridea)” Crustaceana 69(6): 703-718

Toller W., Debrot, A.O., Vermeij, M.J.A., Hoetjes, P.C., (2010) Reef Fishes of Saba Bank, Netherlands

Antilles: Assemblage Structure across a Gradient of Habitat Types. PLoS ONE 5(5): e9207.

doi:10.1371/journal.pone.0009207

Toller, W., 2008. Habitat Surveys of Saba Bank, Netherlands Antilles: An Assessment of Benthic

Communities and Fish Assemblages. Saba Conservation Foundation, Saba, Netherlands Antilles.

Toller, W., Lundvall, S., 2008. Assessment of the commercial fishery of Saba Bank. Saba Conservation

Foundation, 47pp.

Thacker, R.W., Dıaz, M.C., de Voogd, N.J., van Soest, R.W.M., Freeman, C.J. (2010) “Preliminary

Assessment of Sponge Biodiversity on Saba Bank, Netherlands

Antilles” PLoS ONE 5(5): e9622. doi:10.1371/journal.pone.0009622

Tsehaye, I., Machiels, M.A.M., L.A.J. Nagelkerke (2007) “Rapid shifts in catch composition in the

artisanal Red Sea reef fisheries of Eritrea” Fisheries Research 86: 58–68

49

Silberman, J.D., Sarver, S. K., Walsh P. J. (1994) “Mitochondrial DNA variation and population

structure in the spiny lobster Panulirus argus” Marine biology 120 no. 4: 601-608

Smith, K. N., Herrnkind, W. F. (1992) Predation on early juvenile spiny lobsters Panulirus argus

(Latreille): influence of size and shelter. Journal Experimental Marine Biology and Ecology 157:3–18

Tremblay M.J., and Drinkwater K .F. “Temperature, catch rate, and catchability during the spring

lobster fishery off eastern Cape Breton” Department of Fisheries and Oceans Canadian Stock

Assessment Research Document 97/119

Williams, J.T., Carpenter, K.E., Van Tassell, J.L., Hoetjes, P., Toller, W., (2010) “Biodiversity

Assessment of the Fishes of Saba Bank Atoll, Netherlands Antilles” PLoS ONE 5(5): e10676.

doi:10.1371/journal.pone.0010676

Worm, B., Barbier, E.B., Beaumont, N., Duffy, J.E., Folke, C., Halpern, B.S., Jackson J. B. C., Lotze, H.

K., Micheli,F., Palumbi, S. R., Sala, E., Selkoe, K. A., Stachowicz, J. J., Watson, R. (2006) “Impacts of

Biodiversity Loss on Ocean Ecosystem Services” Science 314

Ye, Y., Cochrane, K., Bianchi, G., Willmann, R., Majkowski, J., Tandstad, M., Carocci, F., (2013)

“Rebuilding global fisheries: the World Summit Goal, costs and benefits” Fish and Fisheries 14:174-

185

Yeung, C., and McGowan, M.F., (1991) “Differences in inshore-offshore and vertical distribution of

phyllosoma larvae of Panulirus, Scyllarus and Scyllarides in the Florida Keys in May-June” Bulletin of

marine science 49(3): 699-714

Zhang, Z., 2011. Animal biodiversity: An outline of higher-level classification and survey of taxonomic

richness. Zootaxa 3148

1. http://www.fao.org/fishery/species/3445/en Adjusted from FAO 2013

2. Van Gerwen, Imke. “Carapace length”. 2012. JPEG file.

3. “Carapace length of lobsters” http://law.justia.com/cfr/title50/50-8.0.1.1.10.7.html Visited

Feb. 2013

4. “Fish size” http://www.hillsporthillton.com/graphics/fishsize.gif Visited Feb. 2013

5. Van Gerwen, Imke.

6. Lohman., K. “P. argus phylosoma” http://www.unc.edu/depts/oceanweb/lobs/phylosoma.gif

50

Appendix A

Country Resource Status Management Objectives Current Regulations

Anguilla Fully exploited

Minimum size limits (carapace

length > 95 mm or 7.05oz)

Prohibition on taking berried or tar-

spotted females

Prohibition on taking moulting

individuals

Prohibition on taking lobsters by

spear gun, harpoon or hook of any

description

Antigua & Barbuda

Fully exploited

Sustainable at

current levels of

fishing

Rebuilding stocks in depleted areas

Minimum size limits (carapace

length ≥ 95 mm)

Prohibition on taking berried or

moulting individuals

Prohibition on removal of eggs

from a spiny lobster

Gear restrictions

Prohibition on taking lobsters by

any method other than hand, loop,

pot or trap

Bahamas

Unknown (large

degree of

uncertainty)

Recent declines in

landings

Fisheries

Department

considers stocks in

fairly good

condition

Minimum size limits (carapace

length >82.55 mm and tail length

>139.7 mm)

Prohibition on capture, possession

or sale of berried individuals

Closed season (1 April – 31st July)

Ban on possession of lobster with

swimmerettes removed

Prohibition on removal of eggs

from a spiny lobster

Vessels operating with a

sportfishing permit are allowed

only 10 lobster onboard at any time

Barbados

Unknown

Anecdotal evidence

suggests increase in

abundance

To promote the sustainable harvest

of lobster for domestic use and the

local tourism market in order to

achieve the maximum economic

return from the resource over the

long run

Prohibition on harvest of berried

individuals or removal of eggs

Closed season

Marine Protected Areas

Belize

Overexploited

Threatened by

increase in effort,

inadequate

management,

alteration to habitat

and lack of research

Ensure catch does not exceed

sustainable levels

Discourage destructive fishing

practices

Improve management through

national and international

collaborations

Minimum size limits (carapace

length >3 in. and tail weight >4 oz.)

Prohibition on taking berried or

moulting individuals

Closed season (15th Feb – 14th June)

Ban on landing dead lobsters

Prohibitions on use of SCUBA,

hookah, spearguns and explosives

No fishing in marine reserves or on

the forereef

Table 5: Summary of status, management objectives and current regulations for P. argus fisheries in CARICOM countries. (CRFM, 2011)

51

Country Resource Status Management Objectives Current Regulations

Dominica

Populations of the

south and west

coasts have

declined in

abundance and size

Stocks off northeast

coast considered in

better shape

Rebuild stocks in depleted areas

Minimum size limits (not outlined)

Prohibition on taking berried or

moulting individuals

Closed season (not outlined)

Ban on landing dead lobsters

Prohibitions on use of SCUBA,

spearguns and loops

*Note: Regulations are not currently in

force but used as a matter of policy

Grenada

Overexploited in

nearshore areas

Increasing scarcity

in traditional fishing

areas

Promote sustainable harvest for

local (tourism market) use and

export in order to achieve long

term economic benefits

Rebuild stocks in depleted areas

Minimum size limits

Gear restrictions

Prohibition on taking berried or

moulting individuals

Closed season

Ban on landing dead lobsters

Guyana Guyana does not have a management plan for lobster

Haiti Overexploited

Rehabilitation of degraded habitats

Training of fishermen in basic

literacy and more advanced topics

such as fisheries assessment and

management

Fish stock assessments

Fisher registration

Closed season (April 1 – September

30)

Jamaica Overexploited

Restore/rehabilitate fishery

Control and monitor processing

activities

Optimize foreign exchange earnings

Protect and enhance lobster

habitat

Minimum size limits

Prohibition on taking berried

individuals

End of season declaration of lobster

by processors

Closed season (April 1 – June 30)

Gear restrictions (industrial fishery

only)

No fishing in marine reserves

Montserrat

Lobster populations

off west coast have

declined in size and

abundance

Lobsters off east

coast in relatively

better shape

Rebuild stocks in depleted areas

(particularly off west coast) None

St. Kitts & Nevis

Overexploited in

nearshore areas

Increasing scarcity

in traditional fishing

areas

Rebuild stocks in depleted areas

Minimum size limits

Restrictions on fishing gear

Prohibition on taking berried or

moulting individuals

Closed season

Ban on taking lobsters that are not

whole

Prohibition on use of speargun and

SCUBA

Requirement for marking of traps

St. Lucia

Overexploited in

nearshore areas

Increasing scarcity

in traditional fishing

areas

Sustainable exploitation of stocks

Minimum size limits

Gear restrictions

Prohibition on taking berried or

moulting individuals

Closed season

Prohibition on use of spearguns

and SCUBA

Requirement for marking of traps

52

Country Resource Status Management Objectives Current Regulations

Limited entry for pot fishers

St. Vincent & the

Grenadines Overexploited in

nearshore areas

Rebuild stocks in depleted areas

Sustainable management of the

resource

Minimum size limits

Gear restrictions

Prohibition on taking berried or

moulting individuals

Closed season (May through

August)

Suriname Suriname does not have a management plan for lobster

Trinidad & Tobago Trinidad & Tobago does not have a management plan for lobster

Turks & Caicos Fully

exploited/stable

Reduce fishing effort

Stabilize fluctuations in the fishery

Improve control over size at 1st

capture

To increase revenues

Reduce catches made during the

closed season

Minimum size limits (CL>82.55 mm;

tail>5 oz)

Prohibition on taking berried

individuals

Closed season (April 1st – June 30th)

Ban on SCUBA/hookah diving

Licensing for all fishers, vessels and

processing plants

53

Country

Month

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Anguilla No closed season

Antigua & Barbuda No closed season

Bahamas

Barbados

Belize

Dominica No closed season

Grenada

Guyana No lobster fishery

Haiti

Jamaica

Montserrat No closed season

St. Kitts & Nevis No closed season

Saint Lucia

St. Vincent & the

Grenadines

Suriname No lobster fishery

Trinidad & Tobago No lobster fishery

Turks & Caicos

Appendix a: Seasonal closures for P. argus in CARICOM countries (CRFM, 2011)

54

SABA BANK FISHERIES RESEARCH LOGBOOK

Date:

Boat:

Lobster Pot

Redfish Pot

Longline

No. of Traps: No. of Traps: No. Hooks on Line:

Soak Time: days Soak Time: No. Lines pulled:

Fishing Depth: Fishing Depth: Fishing Depth:

GPS: N 17° GPS: N 17° GPS: N 17°

W 63°

W 63°

W 63°

Quadrat: Quadrat: Quadrat:

Lost traps No Lost traps No

Mixed Fish: Lbs Redfish: Lbs Redfish: Lbs

Lobster: No Mixed Fish: Lbs Mixed fish: Lbs

Berried: No Lobster: No

Shorts: No

Lionfish No Lionfish No Lionfish No

Pelagic Trolling Species

No./Lbs

No. Lines:

Duration (hr):

FAD:

GPS: N 17°

W 63°

Quadrat:

Whales Species Time

Group size Position

Appendix C

55

Fish species FL/TL Fish species FL/TL Fish species FL/TL Fish species FL/TL

Chaetodontidae Haemulidae Priacanthidae Mullidae

Cheatodon striatus TL Haemulon flavolineatum FL Priacanthus arenatus FL Pseudopeneus maculatus FL

Cheatodon capistratus TL Haemulon plumierii FL Aulostomidae Mulloidichthys martinicus FL

Cheatodon ocellatus TL Haemulon carbonarium FL Aulostomus maculatus TL Ginglymostoma cirratum TL

Pomacanthidae Haemulon aurolineatum FL Diodontidae Bothidae

Holacanthus ciliaris TL Haemulon melanurum FL Chilomycterus antillarum TL Bothus lunatus TL

Pomacanthus paru TL Haemulon album FL Chilomycterus antennatus TL Scorpaenidae

Pomacanthus arcuatus TL Lutjanidae

Diodon holocanthus TL Pterois volitans TL

Holacanthus tricolor TL Lutjanus jocu FL Ostraciidae

Acanthuridae Lutjanus apodus FL Acanthostracion polygonia TL

Acanthurus coeruleus TL Lutjanus synagris FL Acanthostracion quadricornis TL

Acanthurus bahianus TL Ocyurus chrysurus FL Lactophrys trigonus TL

Acanthurus chirurgus TL Lutjanus buccanella FL Lactophrys triqueter TL

Carangidae

Rhomboplites aurorubens FL Lactophrys bicaudalis TL

Caranx ruber FL Lutjanus vivanus FL Balistidae

Caranx crysos FL Serranidae

Balistes vetula FL

Sparidae

Epinephelus morio TL Monacanthidae

Calamus calamus FL Mycteroperca venenosa TL Canthidermis sufflamen TL

Scaridae

Epinephelus guttatus TL Aluterus scriptus TL

Sparisoma viride FL Cephalopholis fulva TL Cantherhines pullus TL

Scarus taeniopterus FL Holocentridae Aluterus schoepfi TL

Sparisoma aurofrenatum FL Holocentrus adscensionis FL Cantherhines macrocerus TL

Sparisoma chrysopterum FL Holocentrus rufus FL

Appendix D

56

Appendix E

0

1

2

3

4

5

6

Monday Tuesday Wednesday Thursday Friday Saturday Sunday

No

. Tri

ps

57

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0 20 40 60 80 100 120 140 160 180

Frac

tio

n m

atu

re

Carapace length (mm)

Appendix F

58

Land

ed (#)

Discard

ed

(#)

%

of

total

p

Me

an

(#)

Me

an

(#)

no

n-

zero

CV

no

n-

zero

N

no

n-

zero

catche

s

Ge

om

etric

me

an

(#)

no

n-ze

ro

CI

geo

me

tric

me

an

%

of

total

p

Me

an

(#)

Me

an

(#) no

n-

zero

CV

no

n-

zero

N

no

n-

zero

catche

s

Ge

om

etric

me

an

(#)

no

n-ze

ro

CI

geo

me

tric

me

an

Ch

aeto

do

ntid

ae

Ch

eato

do

n stria

tus

0.7

0

.12

0

.3

2.8

0

.8

4

2.2

2

.1

6.5

0

.67

4

.9

7.3

1

.5

6

4.0

2

.5

Ch

eato

do

n ca

pistra

tus

0.0

0

.00

0

0.3

0

.11

0

.2

2.0

1

2.0

Ch

eato

do

n o

cellatu

s 0

.0

0.0

0

0

0

.1

0.1

1

0.1

1

.0

1

1

.0

P

om

acanth

idae

H

ola

can

thu

s ciliaris

0.0

0

.00

0

0.7

0

.44

0

.6

1.3

0

.4

4

1.2

1

.4

Po

ma

can

thu

s pa

ru

0.5

0

.15

0

.3

1.8

0

.7

5

1.5

1

.7

0.4

0

.22

0

.3

1.5

0

.5

2

1.4

2

.0

Po

ma

can

thu

s arcu

atu

s 0

.1

0.0

3

0.0

1

.0

1

1

.0

0

.3

0.1

1

0.2

2

.0

1

2

.0

H

ola

can

thu

s tricolo

r 0

.2

0.1

2

0.1

1

.0

0.0

4

1

.0

1.0

1

.9

0.4

4

1.4

3

.3

0.9

4

2

.3

2.7

Acan

thu

ridae

A

can

thu

rus co

eruleu

s 3

.2

0.6

1

1.6

2

.7

0.8

2

0

2.1

1

.3

2.9

0

.56

2

.2

4.0

0

.7

5

3.1

2

.1

Aca

nth

uru

s ba

hia

nu

s 3

.2

0.3

3

1.6

4

.8

0.9

1

1

3.5

1

.7

5.6

0

.56

4

.2

7.6

1

.1

5

3.8

3

.5

Aca

nth

uru

s chiru

rgu

s 5

.9

0.4

8

2.9

6

.1

1.1

1

6

3.4

1

.8

2.7

0

.78

2

.0

2.6

0

.8

7

2.0

1

.8

Caran

gidae

C

ara

nx ru

ber

0.1

0

.03

0

.0

1.0

1

1.0

0.6

0

.22

0

.4

2.0

0

.7

2

1.7

3

.0

Ca

ran

x crysos

1.8

0

.03

0

.9

29

.0

1

2

9.0

0.0

0

.00

0

Sparid

ae

Ca

lam

us ca

lam

us

2.2

0

.30

1

.1

3.7

0

.8

10

2

.7

1.8

0

.3

0.1

1

0.2

2

.0

1

2

.0

Scarid

ae

Spa

risom

a virid

e 0

.1

0.0

6

0.1

1

.0

0.0

2

1

.0

1.0

0

.1

0.1

1

0.1

1

.0

1

1

.0

Sca

rus ta

enio

pteru

s 2

.5

0.3

0

1.2

4

.1

0.9

1

0

3.0

1

.7

0.4

0

.22

0

.3

1.5

0

.5

2

1.4

2

.0

Spa

risom

a a

uro

frena

tum

1

.0

0.3

0

0.5

1

.6

0.5

1

0

1.4

1

.4

0.9

0

.44

0

.7

1.5

0

.4

4

1.4

1

.5

Spa

risom

a ch

rysop

terum

1

.5

0.4

2

0.7

1

.7

0.6

1

4

1.5

1

.3

0.3

0

.11

0

.2

2.0

1

2.0

Ap

pe

nd

ix G.Fish

species co

mp

ositio

n o

f land

ed (3

3 trip

s) and

discard

ed (9

trips) catch

es w

ith d

escriptive statistics fo

r each sp

ecies taken

from

no

n-zero

catches b

ased o

n co

un

ts.

Co

lors o

n sp

ecie

s nam

e dep

ict status o

n th

e IUC

N red

list. Gre

en= Least co

ncern

, Grey= n

ot evalu

ated, B

lue= N

ear Threaten

ed, P

urp

le=V

uln

erable, yello

w=n

o d

ata

59

Lan

ded

(#)

D

iscarde

d (#)

%

of

total

p

Me

an

(#)

Me

an

(#)

no

n-

zero

CV

no

n-

zero

N

no

n-

zero

catche

s

Ge

om

etric

me

an

(#)

no

n-ze

ro

CI

geo

me

tric

me

an

%

of

total

p

Me

an

(#)

Me

an

(#) no

n-

zero

CV

no

n-

zero

N

no

n-

zero

catche

s

Ge

om

etric

me

an

(#)

no

n-ze

ro

CI

geo

me

tric

me

an

Hae

mu

lidae

H

aem

ulo

n fla

volin

eatu

m

0.1

0

.03

0

.0

1.0

1

1.0

0.0

0

.00

0

Ha

emu

lon

plu

mierii

28

.4

0.9

7

14

.2

14

.6

0.9

3

2

9.4

1

.5

14

.6

0.3

3

11

.0

33

.0

1.7

3

5

.8

17

.1

Ha

emu

lon

carb

on

ariu

m

0.1

0

.03

0

.0

1.0

1

1.0

1.3

0

.11

1

.0

9.0

1

9.0

Ha

emu

lon

au

rolin

eatu

m

0.1

0

.03

0

.1

2.0

1

2.0

0.0

0

.00

0

Ha

emu

lon

mela

nu

rum

8

.7

0.4

8

4.4

9

.0

2.2

1

6

3.6

1

.8

20

.9

0.4

4

15

.8

35

.5

1.5

4

1

1.5

7

.2

Ha

emu

lon

alb

um

0

.8

0.1

5

0.4

2

.8

0.7

5

2

.4

1.8

0

.1

0.1

1

0.1

1

.0

1

1

.0

Lu

tjanid

ae

Lutja

nu

s jocu

0

.1

0.0

3

0.0

1

.0

1

1

.0

0

.0

0.0

0

0

Lu

tjan

us a

po

du

s 0

.1

0.0

3

0.0

1

.0

1

1

.0

0

.0

0.0

0

0

Lu

tjan

us syn

ag

ris 0

.2

0.0

9

0.1

1

.3

0.4

3

1

.3

1.6

0

.0

0.0

0

0

O

cyuru

s chrysu

rus

0.3

0

.12

0

.2

1.3

0

.4

4

1.2

1

.4

0.1

0

.11

0

.1

1.0

1

1.0

Lutja

nu

s bu

ccan

ella

1.1

0

.06

0

.5

9.0

1

.1

2

5.7

8

.0

0.0

0

.00

0

Rh

om

bo

plites a

uro

rub

ens

0.2

0

.09

0

.1

1.0

0

.0

3

1.0

1

.0

0.0

0

.00

0

Lutja

nu

s vivan

us

1.6

0

.03

0

.8

26

.0

1

2

6.0

0.0

0

.00

0

Serran

idae

Ep

inep

helu

s mo

rio

0.1

0

.03

0

.0

1.0

1

1.0

0.0

0

.00

0

Myctero

perca

venen

osa

0

.0

0.0

0

0

0

.1

0.1

1

0.1

1

.0

1

1

.0

Ep

inep

helu

s gu

ttatu

s 1

0.9

0

.82

5

.5

6.7

1

.6

27

3

.8

1.5

0

.7

0.2

2

0.6

2

.5

0.8

2

2

.0

4.0

Cep

ha

lop

ho

lis fulva

3

.0

0.6

7

1.5

2

.3

1.3

2

2

1.6

1

.4

0.4

0

.11

0

.3

3.0

1

3.0

Ho

loce

ntrid

ae

Ho

locen

trus a

dscen

sion

is 1

.8

0.2

4

0.9

3

.8

1.3

8

2

.1

2.1

1

.2

0.2

2

0.9

4

.0

1.1

2

2

.6

7.0

Ho

locen

trus ru

fus

0.2

0

.06

0

.1

2.0

0

.7

2

1.7

3

.0

1.3

0

.33

1

.0

3.0

0

.7

3

2.5

2

.6

60

Lan

ded

(#)

D

iscarde

d (#)

%

of

total

p

Me

an

(#)

Me

an

(#)

no

n-

zero

CV

no

n-

zero

N

no

n-

zero

catche

s

Ge

om

etric

me

an

(#)

no

n-ze

ro

CI

geo

me

tric

me

an

%

of

total

p

Me

an

(#)

Me

an

(#) no

n-

zero

CV

no

n-

zero

N

no

n-

zero

catche

s

Ge

om

etric

me

an

(#)

no

n-ze

ro

CI

geo

me

tric

me

an

Priacan

thid

ae

Pria

can

thu

s aren

atu

s 0

.1

0.0

3

0.0

1

.0

1

1

.0

0

.0

0.0

0

0

A

ulo

stom

idae

A

ulo

stom

us m

acu

latu

s 0

.0

0.0

0

0

0

.3

0.2

2

0.2

1

.0

0.0

2

1

.0

1.0

Dio

do

ntid

ae

Ch

ilom

ycterus a

ntilla

rum

0

.1

0.0

3

0.1

2

.0

1

2

.0

4

.1

0.7

8

3.1

4

.0

1.2

7

2

.3

2.2

Ch

ilom

ycterus a

nten

na

tus

0.0

0

.00

0

0.1

0

.11

0

.1

1.0

1

1.0

Dio

do

n h

olo

can

thu

s 0

.0

0.0

0

0

0

.3

0.1

1

0.2

2

.0

1

2

.0

O

straciidae

A

can

tho

stracio

n p

olyg

on

ia

5.9

0

.55

3

.0

5.4

0

.6

18

4

.5

1.4

1

4.0

0

.67

1

0.6

1

5.8

0

.6

6

13

.3

1.7

Aca

nth

ostra

cion

qu

ad

ricorn

is 0

.2

0.0

6

0.1

2

.0

0.7

2

1

.7

3.0

5

.8

0.8

9

4.3

4

.9

1.0

8

3

.3

1.9

Lacto

ph

rys trigo

nu

s 0

.4

0.1

2

0.2

1

.5

0.4

4

1

.4

1.5

0

.0

0.0

0

0

La

ctop

hrys triq

ueter

0.5

0

.18

0

.2

1.3

0

.4

6

1.3

1

.3

3.1

0

.67

2

.3

3.5

1

.0

6

2.3

2

.2

Lacto

ph

rys bica

ud

alis

1.0

0

.24

0

.5

2.1

0

.9

8

1.6

1

.7

1.0

0

.67

0

.8

1.2

0

.3

6

1.1

1

.3

Balistid

ae

Ba

listes vetula

6

.1

0.7

6

3.0

4

.0

0.8

2

5

3.1

1

.4

0.0

0

.00

0

Mo

nacan

thid

ae

Ca

nth

iderm

is suffla

men

0

.1

0.0

3

0.0

1

.0

1

1

.0

0

.0

0.0

0

0

A

luteru

s scriptu

s 0

.2

0.0

9

0.1

1

.0

0.0

3

1

.0

1.0

1

.8

0.6

7

1.3

2

.0

0.6

6

1

.7

1.7

Ca

nth

erhin

es pu

llus

0.2

0

.03

0

.1

3.0

1

3.0

0.0

0

.00

0

Alu

terus sch

oep

fi 0

.2

0.0

3

0.1

3

.0

1

3

.0

0

.0

0.0

0

0

C

an

therh

ines m

acro

cerus

0.2

0

.09

0

.1

1.0

0

.0

3

1.0

1

.0

1.8

0

.33

1

.3

4.0

1

.1

3

2.6

3

.7

Mu

llidae

P

seud

op

eneu

s ma

cula

tus

3.0

0

.30

1

.5

4.9

0

.7

10

3

.6

1.8

1

.6

0.3

3

1.2

3

.7

1.0

3

2

.5

3.4

61

M

ullo

idich

thys m

artin

icus

0.4

0

.09

0

.2

2.0

0

.5

3

1.8

1

.9

0.4

0

.11

0

.3

3.0

1

3.0

Lan

ded

(#)

D

iscarde

d (#)

%

of

total

p

Me

an

(#)

Me

an

(#)

no

n-

zero

CV

no

n-

zero

N

no

n-

zero

catche

s

Ge

om

etric

me

an

(#)

no

n-ze

ro

CI

geo

me

tric

me

an

%

of

total

p

Me

an

(#)

Me

an

(#) no

n-

zero

CV

no

n-

zero

N

no

n-

zero

catche

s

Ge

om

etric

me

an

(#)

no

n-ze

ro

CI

geo

me

tric

me

an

Gin

glymo

stom

atidae

Gin

glym

osto

ma

cirratu

m

0.4

0

.06

0

.2

3.0

0

.0

2

3.0

1

.0

1.2

0

.44

0

.9

2.0

0

.7

4

1.7

1

.9

Bo

thid

ae

Bo

thu

s lun

atu

s 0

.0

0.0

0

0

0

.1

0.1

1

0.1

1

.0

1

1

.0

Sco

rpae

nid

ae

Ptero

is volita

ns

0.5

0

.06

0

.3

4.5

0

.2

2

4.5

1

.3

0.1

0

.11

0

.1

1.0

1

1.0

62

Land

ed w

eight (g)

Discard

ed

weigh

t (g)

%

of

total

p

Me

an

we

ight

(g)

Me

an

we

ight

(g)

no

n-

zero

CV

no

n-

zero

N

no

n-

zero

catche

s

Ge

om

etric

me

an

we

ight (g)

no

n-ze

ro

CI

geo

me

tric

me

an

%

of

total

p

Me

an

we

ight

(g)

Me

an

we

ight

(g)

no

n-

zero

CV

no

n-

zero

N

no

n-

zero

catche

s

Ge

om

etric

me

an

we

ight (g)

no

n-ze

ro

CI

geo

me

tric

me

an

Ch

aeto

do

ntid

ae

Ch

eato

do

n stria

tus

0.0

0

.06

7

.3

12

4.2

1

12

4.2

1.7

0

.50

3

05

.1

61

0.2

1

.4

4.0

3

15

.5

3.5

Ch

eato

do

n ca

pistra

tus

0.0

0

.00

0

0.3

0

.13

5

6.4

4

51

.3

1

.0

45

1.3

Ch

eato

do

n o

cellatu

s 0

.0

0.0

0

0

0

.1

0.1

3

10

.5

83

.7

1

.0

83

.7

Po

macan

thid

ae

Ho

laca

nth

us cilia

ris 0

.0

0.0

0

0

1

.7

0.5

0

30

5.5

6

11

.0

0.9

4

.0

48

2.2

2

.1

Po

ma

can

thu

s pa

ru

1.1

0

.12

1

67

.6

14

24

.8

0.1

2

1

42

3.4

1

.1

1.9

0

.25

3

37

.6

13

50

.3

0.3

2

.0

13

11

.7

1.6

Po

ma

can

thu

s arcu

atu

s 0

.0

0.0

0

0

1

.7

0.1

3

29

8.2

2

38

5.3

1.0

2

38

5.3

Ho

laca

nth

us trico

lor

0.1

0

.06

9

.8

16

7.1

1

16

7.1

1.6

0

.38

2

80

.2

74

7.1

0

.7

3.0

5

08

.4

4.3

Acan

thu

ridae

Aca

nth

uru

s coeru

leus

1.7

0

.47

2

72

.0

57

8.0

0

.9

8

44

0.4

1

.7

1.7

0

.38

2

95

.0

78

6.6

0

.5

3.0

7

07

.5

2.0

Aca

nth

uru

s ba

hia

nu

s 1

.8

0.3

5

28

2.4

8

00

.1

1.0

6

4

57

.4

2.8

2

.0

0.6

3

36

2.8

5

80

.5

1.2

5

.0

31

2.1

3

.1

Aca

nth

uru

s chiru

rgu

s 2

.8

0.4

1

43

9.0

1

06

6.1

1

.0

7

60

4.0

2

.6

0.9

0

.50

1

62

.9

32

5.8

1

.0

4.0

2

19

.4

2.8

Caran

gidae

Ca

ran

x rub

er 0

.0

0.0

0

0

1

.5

0.2

5

26

4.8

1

05

9.1

0

.6

2.0

9

71

.3

2.3

Ca

ran

x crysos

4.4

0

.06

7

01

.9

11

93

1.5

1

11

93

1.5

0.0

0

.00

0.0

Sparid

ae

Ca

lam

us ca

lam

us

2.0

0

.24

3

15

.1

13

39

.3

0.7

4

1

03

4.2

2

.4

0.6

0

.13

1

00

.9

80

7.2

1.0

8

07

.2

Table 1

.Fish sp

ecies com

po

sition

of lan

ded

(33

trips) an

d d

iscarded

(8 trip

s) catches w

ith d

escriptive statistics fo

r each sp

ecies taken fro

m n

on

-zero

catches b

ased o

n w

eight (g).

63

Land

ed w

eight (g)

Discard

ed

weigh

t (g)

%

of

total

p

Me

an

we

ight

(g)

Me

an

we

ight

(g)

no

n-

zero

CV

no

n-

zero

N

no

n-

zero

catche

s

Ge

om

etric

me

an

we

ight (g)

no

n-ze

ro

CI

geo

me

tric

me

an

%

of

total

p

Me

an

we

ight

(g)

Me

an

we

ight

(g)

no

n-

zero

CV

no

n-

zero

N

no

n-

zero

catche

s

Ge

om

etric

me

an

we

ight (g)

no

n-ze

ro

CI

geo

me

tric

me

an

Scaridae

Spa

risom

a virid

e 0

.4

0.1

2

67

.6

57

4.5

0

.1

2

57

3.8

1

.1

0.6

0

.13

1

07

.4

85

9.1

1.0

8

59

.1

Scaru

s taen

iop

terus

1.5

0

.29

2

37

.4

80

7.2

1

.2

5

52

8.2

2

.4

0.4

0

.13

7

0.3

5

62

.1

1

.0

56

2.1

Spa

risom

a a

uro

frena

tum

0

.7

0.2

9

11

8.1

4

01

.4

0.5

5

3

54

.2

1.7

0

.6

0.5

0

10

4.1

2

08

.2

0.5

4

.0

18

5.0

1

.8

Spa

risom

a ch

rysop

terum

1

.2

0.3

5

19

7.9

5

60

.7

0.4

6

5

15

.3

1.5

0

.5

0.1

3

91

.8

73

4.4

1.0

7

34

.4

Hae

mu

lidae

Ha

emu

lon

plu

mierii

20

.8

0.9

4

33

22

.8

35

30

.5

0.9

1

6

21

78

.9

1.8

1

6.0

0

.38

2

86

5.3

7

64

0.9

1

.7

3.0

1

08

5.4

2

0.7

Ha

emu

lon

carb

on

ariu

m

0.1

0

.06

1

7.9

3

04

.4

1

3

04

.4

0

.9

0.1

3

15

2.9

1

22

3.2

1.0

1

22

3.2

Ha

emu

lon

au

rolin

eatu

m

0.1

0

.06

1

9.9

3

37

.7

1

3

37

.7

0

.0

0.0

0

0

.0

Ha

emu

lon

mela

nu

rum

1

.9

0.3

5

30

9.0

8

75

.6

0.9

6

5

95

.8

2.2

1

7.9

0

.50

3

19

2.4

6

38

4.8

1

.8

4.0

1

02

2.2

1

1.0

Ha

emu

lon

alb

um

7

.2

0.2

9

11

46

.0

38

96

.4

0.5

5

3

56

6.9

1

.5

1.0

0

.13

1

75

.0

14

00

.0

1

.0

14

00

.0

Lutjan

idae

Lutja

nu

s jocu

0

.0

0.0

0

0

0

.0

0.0

0

0

.0

Lutja

nu

s ap

od

us

0.5

0

.06

7

3.8

1

25

4.4

1

12

54

.4

0

.0

0.0

0

0

.0

Lutja

nu

s syna

gris

0.0

0

.06

7

.2

12

3.1

1

12

3.1

0.0

0

.00

0.0

Ocyu

rus ch

rysuru

s 0

.4

0.1

2

58

.7

49

8.9

0

.1

2

49

7.8

1

.1

0.2

0

.13

3

2.7

2

61

.6

1

.0

26

1.6

Lutja

nu

s bu

ccan

ella

0.3

0

.06

4

9.2

8

35

.8

1

8

35

.8

0

.0

0.0

0

0

.0

Rh

om

bo

plites a

uro

rub

ens

0.1

0

.06

1

8.1

3

07

.9

1

3

07

.9

0

.0

0.0

0

0

.0

64

Land

ed w

eight (g)

Discard

ed

weigh

t (g)

%

of

total

p

Me

an

we

ight

(g)

Me

an

we

ight

(g)

no

n-

zero

CV

no

n-

zero

N

no

n-

zero

catche

s

Ge

om

etric

me

an

we

ight (g)

no

n-ze

ro

CI

geo

me

tric

me

an

%

of

total

p

Me

an

we

ight

(g)

Me

an

we

ight

(g)

no

n-

zero

CV

no

n-

zero

N

no

n-

zero

catche

s

Ge

om

etric

me

an

we

ight (g)

no

n-ze

ro

CI

geo

me

tric

me

an

Serran

idae

Epin

eph

elus m

orio

0

.7

0.0

6

10

4.3

1

77

3.2

1

17

73

.2

0

.0

0.0

0

0

.0

Myctero

perca

venen

osa

0

.0

0.0

0

0

0

.5

0.1

3

80

.8

64

6.6

1.0

6

46

.6

Epin

eph

elus g

utta

tus

15

.0

0.7

6

23

98

.6

31

36

.6

1.1

1

3

19

58

.5

1.8

1

.8

0.2

5

32

6.9

1

30

7.8

1

.1

2.0

8

41

.1

7.5

Cep

ha

lop

ho

lis fulva

2

.0

0.5

9

31

1.3

5

29

.2

0.6

1

0

46

3.5

1

.4

0.4

0

.13

7

8.0

6

23

.7

1

.0

62

3.7

Ho

loce

ntrid

ae

Ho

locen

trus a

dscen

sion

is 0

.1

0.1

2

18

.7

15

9.1

0

.2

2

15

7.7

1

.3

0.6

0

.25

1

10

.6

44

2.5

1

.0

2.0

3

21

.5

5.4

Ho

locen

trus ru

fus

0.0

0

.00

0

0.5

0

.38

8

5.7

2

28

.5

1.1

3

.0

15

5.3

3

.3

Priacan

thid

ae

Pria

can

thu

s aren

atu

s 0

.1

0.0

6

21

.3

36

1.6

1

36

1.6

0.0

0

.00

0.0

Au

losto

mid

ae

Au

losto

mu

s ma

cula

tus

0.0

0

.00

0

0.0

0

.13

3

.1

24

.6

1

.0

24

.6

Dio

do

ntid

ae

Ch

ilom

ycterus a

ntilla

rum

0

.0

0.0

0

0

4

.7

0.8

8

84

2.3

9

62

.6

1.0

7

.0

63

9.5

2

.1

Ch

ilom

ycterus a

nten

na

tus

0.0

0

.00

0

0.0

0

.00

0.0

Dio

do

n h

olo

can

thu

s 0

.0

0.0

0

0

0

.9

0.1

3

16

9.5

1

35

6.3

1.0

1

35

6.3

65

Land

ed w

eight (g)

Discard

ed

weigh

t (g)

%

of

total

p

Me

an

we

ight

(g)

Me

an

we

ight

(g)

no

n-

zero

CV

no

n-

zero

N

no

n-

zero

catche

s

Ge

om

etric

me

an

we

ight (g)

no

n-ze

ro

CI

geo

me

tric

me

an

%

of

total

p

Me

an

we

ight

(g)

Me

an

we

ight

(g)

no

n-

zero

CV

no

n-

zero

N

no

n-

zero

catche

s

Ge

om

etric

me

an

we

ight (g)

no

n-ze

ro

CI

geo

me

tric

me

an

Ostraciid

ae

Aca

nth

ostra

cion

po

lygo

nia

5

.9

0.4

7

93

5.5

1

98

8.0

0

.6

8

16

69

.1

1.6

1

5.0

0

.63

2

67

4.3

4

27

8.9

0

.7

5.0

2

65

1.3

3

.6

Aca

nth

ostra

cion

qu

ad

ricorn

is 0

.1

0.0

6

11

.8

20

1.3

1

20

1.3

4.5

0

.88

7

95

.6

90

9.2

1

.2

7.0

4

57

.6

2.5

Lacto

ph

rys trigo

nu

s 1

.1

0.1

2

17

6.5

1

50

0.4

0

.5

2

14

18

.3

2.0

0

.0

0.0

0

0

.0

Lacto

ph

rys triqu

eter 1

.0

0.1

2

15

2.6

1

29

7.1

0

.3

2

12

71

.1

1.5

2

.0

0.6

3

35

9.9

5

75

.9

1.1

5

.0

32

4.6

2

.9

Lacto

ph

rys bica

ud

alis

0.1

0

.18

2

3.5

1

33

.2

0.3

3

1

29

.8

1.4

0

.9

0.3

8

15

7.0

4

18

.7

0.6

3

.0

36

2.9

2

.2

Balistid

ae

Ba

listes vetula

2

0.8

0

.82

3

32

0.7

4

03

2.3

0

.8

14

2

80

1.1

1

.7

0.0

0

.00

0.0

Mo

nacan

thid

ae

Ca

nth

iderm

is suffla

men

0

.5

0.0

6

87

.5

14

87

.2

1

1

48

7.2

0.0

0

.00

0.0

Alu

terus scrip

tus

0.4

0

.12

6

4.5

5

48

.0

0.1

2

5

47

.3

1.1

0

.3

0.5

0

54

.5

10

9.0

0

.6

4.0

9

4.7

1

.8

Ca

nth

erhin

es pu

llus

0.0

0

.00

0

0.0

0

.00

0.0

Alu

terus sch

oep

fi 0

.3

0.0

6

54

.6

92

8.1

1

92

8.1

0.0

0

.00

0.0

Ca

nth

erhin

es ma

croceru

s 0

.5

0.1

2

85

.6

72

7.6

0

.1

2

72

7.1

1

.1

3.2

0

.38

5

76

.2

15

36

.4

1.4

3

.0

68

2.7

6

.1

Mu

llidae

Pseu

do

pen

eus m

acu

latu

s 0

.2

0.1

2

27

.6

23

4.4

0

.2

2

23

1.3

1

.4

1.3

0

.38

2

29

.9

61

3.0

1

.1

3.0

3

89

.4

4.0

Mu

lloid

ichth

ys ma

rtinicu

s 0

.1

0.0

6

23

.6

40

0.4

1

40

0.4

0.8

0

.13

1

41

.7

11

33

.4

1

.0

11

33

.4

66

Land

ed w

eight (g)

Discard

ed

weigh

t (g)

%

of

total

p

Me

an

we

ight

(g)

Me

an

we

ight

(g)

no

n-

zero

CV

no

n-

zero

N

no

n-

zero

catche

s

Ge

om

etric

me

an

we

ight (g)

no

n-ze

ro

CI

geo

me

tric

me

an

%

of

total

p

Me

an

we

ight

(g)

Me

an

we

ight

(g)

no

n-

zero

CV

no

n-

zero

N

no

n-

zero

catche

s

Ge

om

etric

me

an

we

ight (g)

no

n-ze

ro

CI

geo

me

tric

me

an

Gin

glymo

stom

atidae

Gin

glym

osto

ma

cirratu

m

1.9

0

.06

2

97

.8

50

62

.4

1

5

06

2.4

8.7

0

.38

1

56

2.9

4

16

7.7

1

.2

3.0

2

44

6.3

4

.1

Bo

thid

ae

Bo

thu

s lun

atu

s 0

.0

0.0

0

0

0

.3

0.1

3

45

.0

35

9.6

1.0

3

59

.6

Scorp

aen

idae

Ptero

is volita

ns

0.0

0

.00

0

0.0

0

.00

0.0