NIWA Client report...Jane Halliday James Sturman For any information regarding this report please contact: [email protected] Contracts Manager +64-4-386 0369 Neville Ching National

Volume Two May 2014

Appendix 20

Distribution patterns of cetaceans on the Chatham Rise (Torres et al. 2013a)

Distribution patterns of cetaceans on the Chatham Rise

Prepared Chatham Rock Phosphate Limited

November 2012 (Updated April 2013)

A group of pilot whales, Chatham Rise. Owen Anderson, NIWA.

© All rights reserved. This publication may not be reproduced or copied in any form without the permission of the copyright owner(s). Such permission is only to be given in accordance with the terms of the client’s contract with NIWA. This copyright extends to all forms of copying and any storage of material in any kind of information retrieval system.

Whilst NIWA has used all reasonable endeavours to ensure that the information contained in this document is accurate, NIWA does not give any express or implied warranty as to the completeness of the information contained herein, or that it will be suitable for any purpose(s) other than those specifically contemplated during the Project or agreed by NIWA and the Client.

Authors/Contributors: Leigh G. Torres Jane Halliday James Sturman

For any information regarding this report please contact:

[email protected] Contracts Manager +64-4-386 0369 Neville Ching

National Institute of Water & Atmospheric Research Ltd

301 Evans Bay Parade, Greta Point

Wellington 6021

Private Bag 14901, Kilbirnie

Wellington 6241

New Zealand

Phone +64-4-386 0300

Fax +64-4-386 0574

NIWA Client Report No: CRP12302 Report date: November 2012 (Updated April 2013)April 2013 NIWA Project: WLG2011-67


Contents

Executive summary .............................................................................................................. 6

1 Introduction ................................................................................................................. 7

2 Species accounts ...................................................................................................... 11

2.1 Toothed whales and dolphins (Odontoceti) ........................................................ 11

2.2 Baleen whales (Mysticeti) ................................................................................... 20

2.3 Summary of cetacean habitat use and foraging patterns .................................... 24

3 Threats to cetaceans ................................................................................................. 27

3.1 Ship strike .......................................................................................................... 27

3.2 Noise .................................................................................................................. 28

3.3 Habitat degradation ............................................................................................ 29

3.4 Entanglement ..................................................................................................... 29

3.5 Pollution ............................................................................................................. 29

4 Potential impacts on cetaceans by Chatham Rock Phosphate Ltd. mining

activities ..................................................................................................................... 30

4.1 Ship strike .......................................................................................................... 30

4.2 Noise .................................................................................................................. 30

4.3 Habitat degradation ............................................................................................ 31

4.4 Entanglement ..................................................................................................... 31

4.5 Pollution ............................................................................................................. 31

5 Summary and Conclusions ...................................................................................... 32

6 Acknowledgements ................................................................................................... 32

7 References ................................................................................................................. 32

8 Appendices ................................................................................................................ 39

8.1 Appendix A: Marine mammal sound production characteristics (Wartzok &

Ketten 1999) ...................................................................................................... 39

8.2 Appendix B: Underwater audiograms for (a) odontocetes and (b) pinnipeds

(Wartzok & Ketten 1999) .................................................................................... 45


Tables

Table 11: Sighting records from DOC and Cawthron datasets of 12 cetaceans species and one species group (beaked whales) observed over the Chatham Rise. Species are listed alphabetically and sightings per season are given. Listing is according to the New Zealand Threat Ranking (Baker et al. 2010). Summer: Dec - Feb; Autumn: Mar - May; Winter: Jun - Aug; Spring: Sep -Nov. 9

Table 2-1: General habitat use and foraging patterns of the 12 species and 1 species group of cetaceans recorded near the permit area. 25

Table 3-1: Strandings in the Canterbury and Otago regions reported as 'collision/accident' in the Department of Conservation whale stranding database. 26

Figures

Figure 1-1: Distribution of all cetacean sighting locations, by species, from DOC and Cawthorn datasets within the Chatham Rise study area. The 100 km buffer of the study area is shown by the red box. Chatham Rock Phosphate Ltd. mineral extraction permitted area shown in red; benthic protected areas shown in pink. 10

Figure 2-1: Distribution of dolphin sightings by season, from DOC and Cawthorn datasets within the Chatham Rise study area. The 100 km buffer of the study area is indicated by the red box. Chatham Rock Phosphate Ltd. mineral extraction permitted area shown in red; benthic protected areas shown in pink. 11

Figure 2-2: Distribution of sperm whale sightings by season, from DOC and Cawthorn datasets within the Chatham Rise study area. The 100 km buffer of the study area is indicated by the red box. Chatham Rock Phosphate Ltd. mineral extraction permitted area shown in red; benthic protected areas shown in pink. 13

Figure 2-3: Seasonal habitat prediction maps of sperm whales in the region east of New Zealand, including over the Chatham Rise. 14

Figure 2-4: Distribution of pilot whale sightings by season, from DOC and Cawthorn datasets within the Chatham Rise study area. 16

Figure 2-5: Distribution of killer whale sightings by season, from DOC and Cawthorn datasets within the Chatham Rise study area. 18

Figure 2-6: Distribution of all baleen whale sightings from DOC and Cawthorn datasets within the Chatham Rise study area. 20

Figure 2-7: Seasonal habitat prediction maps of southern right whales in the region around New Zealand, including over the Chatham Rise. Prediction maps derived from habitat models generated using historical whaling data and boosted regression trees (Torres et al. 2011). Resolution is 70 X 70 km. Colour ramp indicates high and low values of predicted sperm whale presence and are comparable between seasons. (a) Spring: September, October, November. (b) Summer: December, January, February. (c) Autumn: March, April, May. No prediction map for winter generated because whales on calving grounds. Black star indicates approximate location of CRP permit area. 24

Distribution patterns of cetaceans on the Chatham Rise 5

Reviewed by Approved for release by David Thompson Julie Hall

6 Distribution patterns of cetaceans on the Chatham Rise

Executive summary This report describes distribution patterns of cetaceans on the Chatham Rise. Two datasets

of opportunistic sightings of cetacean species were used to describe their distribution

patterns along the Chatham Rise of New Zealand: (1) The Department of Conservation

(DOC) cetacean sightings data, and (2) a dataset provided by Martin Cawthorn of incidental

cetacean sightings by transiting ships. The datasets provide 137 records of 12 different

cetacean species and one species group (beaked whales) sighted within the study area

consisting of approximately 100 km buffer area of the Chatham Rock Phosphate Ltd. mining

permit area. The majority of the sightings of cetacean within the study area are of sperm

whales (Physeter macrocephalus) and pilot whales (Globicephala spp.), which prefer habitat

over the Chatham Rise slopes where they forage in steep slope habitat. Additionally, various

species of dolphins, baleen whales and beaked whales use and transit through this area

including the Nationally Critical killer whale (Orcinus orca) and the Nationally Endangered

southern right whale (Eubalaena australis). Recent habitat modelling has revealed that the

southern edge of the Chatham Rise is an important foraging ground for southern right whales

during summer and autumn.

Due to limited cetacean distribution data over the Chatham Rise, it is difficult to assess the

impact from the dredging operations and disposal system on cetaceans. However, the main

potential impacts to cetaceans are (1) decreased foraging efficiencies due to habitat

disturbance and increased turbidity and (2) decreased capabilities of acoustic communication

and perception due to increased noise in their environment. The longevity and intensity of

these impacts will depend on the duration of operations and extent of environmental

disturbance. Based on the slow travel speed of the dredging vessel while operating, it is

unlikely that a collision with a cetacean will occur. However, transiting vessels to and from

the dredging site run a greater risk of ship strike, particularly around the southern edge of the

Chatham Rise during summer and autumn when this habitat is important for foraging

southern right whales. Southern right whales are particularly prone to lethal vessel collisions.


1 Introduction Two datasets of opportunistic sightings of cetacean species were used to describe their

distribution patterns over the Chatham Rise of New Zealand, and within the Chatham Rock

Phosphate Ltd. mining area: (1) The Department of Conservation (DOC) cetacean sightings

data (Department of Conservation 2012a), and (2) a dataset provided by Martin Cawthorn of

incidental cetacean sightings by transiting ships (Cawthorn 2009). Cetaceans are mobile and

dynamic animals that travel between areas in search of prey and preferred habitat. The

distribution of cetaceans within three spatial areas is discussed: (1) within the Chatham Rock

Phosphate Ltd. mining permit area, (2) within an approximately 100 km buffer area of the

Chatham Rock Phosphate Ltd. mining permit area, and (3) beyond the 100 km buffer area

over the Chatham Rise. Available cetacean sightings data within these areas is presented

and species ecology is discussed based on relevant literature and reports.

In summation, these two datasets provide 137 records of 12 different cetacean species and

one species group (beaked whales) sighted between July 1981 and November 2007 within

the Chatham Rise study area (Figure 1-1, Table 1-1). Within this dataset there are sighting

records of one Nationally Critical species, the killer whale (Orcinus orca), and there are also

sightings of the Nationally Endangered southern right whale (Eubalaena australis) in the

vicinity of the study area (Figure 1-1). Seasonal variation in the number of cetacean sightings

is apparent within this dataset (Table 1-1). There is a peak in sightings during summer

months (Dec – Feb) with species composition dominated by sperm (Physeter

macrocephalus) and pilot whales (Globicephala spp.). There are also a large number of

sightings in Spring (Sep - Nov) and Winter (Jun - Aug) months with greater diversity of

species. The least number of sightings occurred during Autumn (Mar – May). It is important

to note that these sighting rates are biased due to observational effort and cannot be

considered representative of actual temporal distribution of cetaceans over the Chatham

Rise. Moreover, cautious interpretation of these sightings data is warranted due to a lack of

standardized observational effort and absence data. However, apparent trends in spatial

distribution patterns of these cetacean species are described below.

Species accounts are given for each species or species group observed in the Chatham Rise

study area. Emphasis is given to those species that were most frequently sighted (sperm

whales, pilot whales) and those considered threatened (killer whales, southern right whales)

by the New Zealand Threat Ranking (Baker et al. 2010). The ecology and habitat use

patterns of these species are detailed and a discussion of their potential for interaction with,

and response to, the dredging and sediment disposal system is provided.

The majority of the sightings of cetaceans within the Chatham Rise study area are of sperm

and pilot whales. These sightings are concentrated along shelf breaks in areas of high slope,

where they are known to feed on squid (Gannon et al. 1997, Gaskin 1973). Three species of

dolphin (bottlenose (Tursiops spp.), common (Delphinus spp.) and dusky (Lagenorhynchus

obscurus) were also sighted within the Chatham Rise study area. Our limited sightings data

of these species reveal no preference for a particular water depth or season. Additionally,

sightings of various species of migratory baleen whales occurred over the Chatham Rise

area, likely made as the animals travel between their summer feeding grounds toward the

south and their northern breeding grounds during winter months. An important exception is

for the southern right whale where recent habitat modelling (Torres et al. 2011) revealed that


the southern edge of the Chatham Rise is important foraging habitat for southern right

whales during the summer and autumn months.

A section on known threats to cetaceans is provided. Particular emphasis is given to

describing existing knowledge concerning vessel interactions with cetaceans (ship strikes)

and useful mitigation measures. A review of known ship strike events in New Zealand is

provided with emphasis on the east coast of the South Island. A review of other threats to

cetaceans (Entanglement, Noise, Pollution, Habitat Degradation) is also provided.


Table 1-1: Sighting records from DOC and Cawthron datasets of 12 cetaceans species and one species group (beaked whales) observed over the Chatham Rise. Species are listed alphabetically and sightings per season are given. Listing is according to the New Zealand Threat Ranking (Baker et al. 2010). Summer: Dec - Feb; Autumn: Mar - May; Winter: Jun - Aug; Spring: Sep -Nov.

Species Listing Spring Summer Autumn Winter Unknown Total

Beaked whales 2 1 3

Blue whale (Balaenoptera musculus) Migrant 1 1 2

Bottlenose dolphin (Tursiops truncatus) Range restricted 2 1 2 1 6

Common dolphin (Delphinus spp.) Not threatened 1 6 1 8

Dusky dolphin (Lagenorhynchus obscurus) Not threatened 2 2 4

False killer whale (Pseudorca crassidens) Not threatened 1 1

Humpback whale (Megaptera novaeangliae) Migrant 2 2 4

Killer whale (Orcinus orca) Nationally critical 4 3 3 1 1 12

Minke whale (Balaenoptera bonaerensis) Migrant 2 2 1 5

Pilot whale (Globicephala spp.) Not threatened 9 9 5 4 27

Sei whale (Balaenoptera borealis) Migrant 1 1

Southern right whale (Eubalaena australis)

Nationally endangered 1 1

Sperm whale (Physeter macrocephalus) Not threatened 12 21 6 17 7 63

Total 33 43 19 28 14 137


Figure 1-1: Distribution of all cetacean sighting locations, by species, from DOC and Cawthorn datasets within the Chatham Rise study area. The 100 km buffer of the study area is shown by the red box. Chatham Rock Phosphate Ltd. mineral extraction permitted area shown in red; benthic protected areas shown in pink.


2 Species accounts

2.1 Toothed whales and dolphins (Odontoceti)

Sightings of all odontocetes (toothed whales and dolphins) in the Chatham Rise are depicted

in Figure 1-1. The small delphinids showed no preference for a particular area within the

study area or depth of water (Figure 2-1). However, pilot whales, false killer whales, and killer

whales appear to concentrate near the 1000 m isobaths over the Chatham Rise slope edge.

The majority of the sightings of large odontocetes (sperm whales) are also near the 1000 m

isobath.

Figure 2-1: Distribution of dolphin sightings by season, from DOC and Cawthorn datasets within the Chatham Rise study area. The 100 km buffer of the study area is indicated by the red box. Chatham Rock Phosphate Ltd. mineral extraction permitted area shown in red; benthic protected areas shown in pink.

2.1.1 Sperm whale (Physeter macrocephalus)

IUCN Threat Classification: Vulnerable

New Zealand Threat Ranking (Baker et al. 2010): Not Threatened

One sighting of a sperm whale was made in the Chatham Rock Phosphate Ltd. mineral

permit area in the summer of 1985, and an additional 21 sightings of sperm whales were

made in the 100 km buffer study area (Figure 2-2). The majority of the sightings were made

in summer (Figure 2-2, Table 1-1). Many more sperm whale sightings have been recorded

outside the study area over the Chatham Rise (Figure 2-2). Almost all sightings were

recorded near the 1000 m isobath at the slope edge.


The year round presence of sperm whales on the Chatham Rise has been documented

(Berzin 1971, Gaskin 1973). Sperm whales are known to concentrate in deep water habitats

near steep continental shelves and areas with strong temperature gradient that provide

optimal habitat conditions for their main prey, cephalopods (Berzin 1971, Clarke 1996,

Shirihai 2002). The northern and southern slopes of the Chatham Rise are steep slope

habitat. Additionally, the Chatham Rise has a steep temperature gradient as the Sub-Tropical

Front flows along the southern edge of the Chatham Rise, acting as a boundary between

warm (sub-tropical) and cold (sub-Antarctic) water masses.

Sperm whales feed at great depths where there is no light except for bioluminescence

(Watkins et al. 1993). Bioluminescent cephalopods can comprise up to 87% of sperm whale

diet (Clarke 1980). Sperm whales typically dive to depths of 300-800 m for approximately 40

minutes, with some dives lasting as long as 1.5 hours and down to 1000 m (Whitehead &

Weilgart 2000). Sperm whales forage in the mid-water and near the bottom. Their dives are

usually signalled by the raising of flukes out of the water. The descent to depth, as well as

the return to the surface, can be nearly vertical (Whitehead 2009). While foraging, sperm

whales generally make regularly spaced clicks at intervals of 0.5–1.0 sec, used as a

searching sonar (Watwood et al. 2006). These are interrupted by creaks, consisting of clicks

with accelerating rates, which are assumed to indicate short-range sonar during prey capture

events. It is thought that echolocation is the primary way prey is found, however vision may

also be important in finding food at close range in response to the bioluminescence of their

squid prey. Spawning aggregations of squid prey of sperm whales have been documented

over the Chatham rise (Gomez-Villota 2007, Jackson 2001).

Adult male sperm whales are solitary while females and associated calves and juveniles

travel together in groups. Eight of the sightings within the study area were of solitary sperm

whales, which likely represent adult males. The other 12 sightings were likely maternal

groups: nine sightings were of small groups (2-4 individuals) and three sightings were of

larger groups (7-10 individuals). These data indicate that the Chatham Rise habitat is used

by both adult males and mother/calf groups. Indeed, whaling records indicate that both males

and females were taken over the Chatham Rise in approximately equal numbers (Gaskin

1973). Groups of females and associated calves and juveniles typically spread out over 1 km

or more of ocean when foraging, while males seem generally to forage independently

(Whitehead 2009). Mating between sperm whales occurs at all times of the year (Berzin

1971) and it is possible that sperm whale mating occurs over the Chatham Rise because

sperm whales of both sexes congregate here.

Sperm whales are long-lived (60 -70 yrs) animals, with low natural mortality and very low

fecundity (Whitehead & Weilgart 2000). Females have on average one calf every 5 – 10

years. Prior to whaling, the global population of sperm whales was estimated at a million, and

possibly a hundred thousand sperm whales survived the recent phase of whaling (Whitehead

& Weilgart 2000). Little is known of the population’s present conservation status, but their low

reproduction rates means they cannot recover from population declines quickly.


Habitat models of sperm whale distribution in a large-scale area to the east of New Zealand

and Tasman Sea (approx. 10S to 55S, 170E to 130W) were created from 19th century

whaling records (Torres et al. 2011). The seasonal predictive maps indicate relatively high

presence of sperm whales (> 0.7) over the Chatham Rise in all seasons except winter when

habitat suitability reduces to ~0.55 (

Figure 2-3). These predictions do not allow fine-scale predictions of sperm whale presence in

the Chatham Rock Phosphate Ltd. area of interest due to a large spatial resolution of 70 X

70 km. However, this study (Torres et al. 2011) and predictive maps do indicate the relative

importance of the habitat over Chatham Rise to sperm whales within the larger New Zealand

region.

While at the surface, sperm whales may be travelling, socializing or recovering from a

foraging dive. This recovery time is important to the physiology and behaviour of sperm

whales because it allows individuals to re-oxygenate blood and recuperate organs that are

‘shut-down’ during their extreme dives (Kooyman 2009). Therefore, it is important not to

disturb sperm whales during this recovery period as this may cause stress that would impair

their recovery.

Figure 2-2: Distribution of sperm whale sightings by season, from DOC and Cawthorn datasets within the Chatham Rise study area. The 100 km buffer of the study area is indicated by the red box. Chatham Rock Phosphate Ltd. mineral extraction permitted area shown in red; benthic protected areas shown in pink.


Figure 2-3: Seasonal habitat prediction maps of sperm whales in the region east of New Zealand, including over the Chatham Rise. Prediction maps derived from habitat models generated using historical whaling data and boosted regression trees (Torres et al. 2011). Resolution is 70 X 70 km. Colour ramp indicates high and low values of predicted sperm whale presence and are comparable between seasons. Spring: September, October, November. Summer: December, January, February. Autumn: March, April, May. Winter: June, July, August. Black star shows approximate location of CRP permit area.

2.1.2 Pilot whale (Globicephala spp.)

IUCN Threat Classification: Data Deficient


Pilot whales are wide ranging with two species found in NZ waters: long-finned pilot whales

(Globicephala melas) and short-finned pilot whale (Globicephala macrorhynchus). Generally,

short-finned pilot whales have a tropical and sub-tropical distribution, and long-finned pilot

whales are distributed antitropically. Therefore, it is likely that the majority of the sightings of

pilot whales in the Chatham Rise area are long-finned pilot whales. Long-finned pilot whales

inhabit the cold temperate waters of both the North Atlantic and the Southern Ocean, and

those in the Southern Hemisphere are recognized as subspecies G. melas edwardii.

A total of 18 pilot whales sightings within the 100 km buffer study area, consisting of an

estimated 331 individuals, have been recorded (Figure 2-4). Two pilot whale sightings were

recorded close to (within 12 km) the Chatham Rock Phosphate Ltd. permit area. An

additional nine pilot whale sightings have been reported over the Chatham Rise beyond the

100 km buffer area (Figure 2-4). The majority of pilot whale sightings were in the western half

of the study area. No sightings were made in autumn months, five in winter, nine in spring,

nine in summer months, and four unknown (Table 1-1). No seasonality can be assumed due

to the unstandardized nature of these opportunistic sighting data.


Pilot whales are generally nomadic and their movements are considered to be related to the

distribution of squid, their preferred prey. Studies in Newfoundland and California correlated

the seasonal abundance of pilot whales with spawning squid (Olson 2009). The pilot whale

diet consists primarily of squid, with lesser amounts of fish. Common habitats of pilot whales

are shelf breaks, slope waters, and areas of high topographic relief. The Chatham Rise slope

is characterized by these features. Pilot whales can make deep dives (up to 1000 m) in

search of prey (Shirihai 2002).

Pilot whales have a long life span, delayed maturity, different rates of maturation for males

and females, seasonal mating, and the production of a single calf in multiyear intervals

(Olson 2009). Pilot whales are highly social and are usually found in groups averaging 20 –

90 individuals (Olson 2009, Shirihai 2002). Group behaviours typically include traveling or

foraging in a loose chorus-line formation or logging (resting) at the surface. The social

structure of pilot whale groups consists of stable pods composed of individuals with close

matrilineal associations (Amos et al. 1993). All age and sex classes are included, although

there is a female bias in adults. Pilot whales grow to maturity in their natal group and most

remain there for life. Pilot whales are also known to associate with other species of whales

and dolphins (Olson 2009, Shirihai 2002). The birth interval in pilot whales is one of the

longest of all the cetaceans. Lactation lasts for at least three years, often longer. Such an

extended lactation period indicates extended investment in calf rearing and social

development. Females live past 60 years, while males reach 35 – 45 years (Olson 2009).

Pilot whales use acoustic signals to echolocate and communicate. A primary purpose of

vocalizations is to maintain contact with conspecifics of their social groups. Such

communication is maintained even during deep foraging dives up to 800 m (Jensen et al.

2011). Adverse responses of pilot whales to anthropogenic noise have been documented,

including seismic activity (Weir 2008) and vessel noise (Jensen et al. 2009).

Strandings of long-finned pilot whales occur throughout the coastlines of New Zealand, with

peaks in stranding events in spring and summer months (O'Callaghan et al. 2001). Over the

25 years from 1976 to 2000, 165 long-finned pilot whale strandings have been reported. Of

these, 83 were mass strandings (two or more individuals) and 82 were single strandings.

Twenty nine of these occurred on the Chatham Islands and 6 on the north-east coast of

South Island (O'Callaghan et al. 2001). Since then, a large stranding of 100 pilot whales

occurred on Mairangi Beach, north east of Chatham Island in March 2009 (DOC website).

The true cause of strandings is unknown, but hypotheses include disorientation due to

acoustics noise in the ocean and reduced prey availability due to fisheries.


Figure 2-4: Distribution of pilot whale sightings by season, from DOC and Cawthorn datasets within the Chatham Rise study area. The 100 km buffer of the study area is indicated by the red box. Chatham Rock Phosphate Ltd. mineral extraction permitted area shown in red; benthic protected areas shown in pink.

2.1.3 Short beaked (Delphinus delphis) and long beaked (D. capensis) common dolphin

IUCN Threat Classification: Least concern


The DOC and Cawthorn datasets include 4 sightings of common dolphins within the

Chatham Rise study area, and one of these sightings was within the Chatham Rock

Phosphate Ltd. permit area (Figure 2-1). These sightings were not identified to sub-species.

Four additional sightings of common dolphins have been reported over the Chatham Rise

beyond the 100 km buffer area. Six of these sightings were recorded in autumn, one in winter

and one in spring (Table 1-1). However, no seasonality can be assumed due to the

unstandardized nature of these opportunistic sighting data. A study of common dolphins that

examined the stomach contents of by-caught or stranded animals in New Zealand found that

their diet comprised a diverse range of fish and cephalopod species, with the predominant

prey being arrow squid (Nototodarus sloanii), jack mackerel (Trachurus novaezelandiae),

and anchovy (family Engraulidae; Meynier et al. 2008). The authors suggested that the

mixed prey composition in the diet of common dolphins by-caught in waters further offshore

may be due to inshore/offshore movements of common dolphin. No other studies of common

dolphin ecology have been conducted within in the Chatham Rise. However, the general

habitat ecology of common dolphins is typically warmer temperate or tropical waters and

principally offshore (Shirihai 2002). Common dolphins generally feed in shallower areas of


the water column (<500 m) on small to mid-sized fish and squid associated with the mixed

scattering layer.

2.1.4 Killer whale (Orcinus orca)


New Zealand Threat Ranking (Baker et al. 2010): Nationally Critical

Killer whales are classified as a Nationally Critical threatened species in New Zealand mainly

due to their small population size estimated to be 119 (SE 24; Visser 2000). The New

Zealand killer whale population has a broad distribution around both North and South Islands

(Visser 2000). Killer whales do not have a defined migration cycle, but likely travel between

preferred habitats in search of seasonally abundant prey items such as fish, other marine

mammals, and sharks and rays (Constantine et al. 1998, Visser 1999, Visser 2000, Visser

2005, Visser et al. 2000, Visser et al. 2010). Due to their flexible foraging strategies and

diverse diet, the habitat use patterns of killer whales can vary between shallow to middle

water depths (< 500m) and benthic and pelagic habitats. It is thought that killer whales may

use the Chatham Islands area during summer months to take advantage of feeding

opportunities due to the fur seal breeding season. As the New Zealand population of killer

whales is very small, it is important to reduce any impacts on this species’ ecology or

population status.

Between 1985 and 2003, four sightings of killer whales were recorded within the 100 km

buffer study area (consisting of 17 individuals) (Figure 2-5). Three of the four sightings were

in spring, with the other sighting at an unknown time of year (Table 1-1). An additional eight

sightings of killer whales have been recorded over the Chatham Rise beyond the 100 km

buffer area (Figure 2-5). The season of these 12 killer whale sightings over the Chatham

Rise are spread throughout the year (Table 1-1).


Figure 2-5: Distribution of killer whale sightings by season, from DOC and Cawthorn datasets within the Chatham Rise study area. The 100 km buffer of the study area is indicated by the red box. Chatham Rock Phosphate Ltd. mineral extraction permitted area shown in red; benthic protected areas shown in pink.

2.1.5 Dusky dolphin (Lagenorhynchus obscurus)

IUCN Threat Classification: Data Deficient New Zealand Threat Ranking (Baker et al. 2010): Not Threatened

Dusky dolphins are regarded as not threatened in New Zealand (Baker et al. 2010). They

tend to inhabit cooler waters off most of the South Island and the lower part of the North

Island (Wursig et al. 2007). Two sighting of dusky dolphin groups were made within the 100

km buffer study area: one in 1984 with an estimated 220 individuals and the other sighting of

a smaller group of 20 individuals in 1998. Two additional sightings of dusky dolphins have

been recorded over the Chatham Rise beyond the 100 km buffer area (Figure 2-1). Two

dusky dolphin sightings were made in spring and two in summer (Table 1-1). All dusky

dolphin sightings were all made near the 500 m isobath (Figure 2-1). Dusky dolphins

generally feed in shallower areas of the water column (<500 m) on small to mid-sized fish

and squid associated with the mixed scattering layer.


2.1.6 Bottlenose dolphin (Tursiops spp.)

IUCN Threat Classification: Data Deficient New Zealand Threat Ranking (Baker et al. 2010): Nationally Endangered

Two sightings of bottlenose dolphins were made in the study area, one in the spring of 2002

with an estimated 50 individuals and the other smaller group of 30 individuals in 2005

(season unknown; Figure 2-1, Table 1-1). Inshore bottlenose dolphins (Tursiops truncatus)

are regarded as range restricted in New Zealand. However, the size of the bottlenose dolphin

groups observed, and their distance from shore, suggests that these dolphins are from an

‘offshore’ ecotype known as Tursiops aduncus. Although the offshore ecotype is not

considered ‘range restricted’, very little is known about their distribution or ecology. Four

additional sightings of bottlenose dolphins have been recorded over the Chatham Rise

beyond the 100 km buffer (Figure 2-1). Bottlenose dolphins generally feed in shallower areas

of the water column (<500 m) on small to mid-sized fish and squid associated with the mixed

scattering layer.

2.1.7 False killer whale (Pseudorca crassidens)

IUCN Threat Classification: Data Deficient New Zealand Threat Ranking (Baker et al. 2010): Not Threatened

Only one sighting of a false killer whale group of 10 to 15 individuals during the spring of

1985 was recorded within the 100 km study area (Figure 1-1, Table 1-1). This sighting was

made in the Chatham Rise slope area. Like pilot whales, a similar species, false killer whales

typically occur in deep water habitats and along shelf edges (200 - 2000 m, Shirihai 2002)

and are deep divers (~600 to 1000 m).

2.1.8 Beaked whales (family Ziphiidae)

IUCN Threat Classification: Data Deficient New Zealand Threat Ranking (Baker et al. 2010): Data Deficient

There are at least 20 species of beaked whales known globally, half of which occur in New

Zealand waters. Due to their low profile in the water and their similar appearance, it is difficult

for ship based observers to identify these whales to species level so they are usually

grouped together. Little is known about these animals. However, their ecology includes a

preference for high slope and canyon habitats where they feed on fish and squid as deep

divers (~1000 m). Although this group of whales was not observed in the Chatham Rise

study area, three groups were observed just beyond the 100 km buffer study area (Figure

1-1). A total of 27 individuals were observed in the three pods. Two of the observations were

made in summer and the other was made in winter (Table 1-1).


2.2 Baleen whales (Mysticeti)

Minke whales (Balaenoptera bonaerensis) were the only species of baleen whales recorded

within the 100 km buffer study area from the DOC and Cawthorn datasets. The four sightings

of minke whales (nine individuals) were in spring, summer and winter (Figure 2-6). Four other

species of baleen whales were observed beyond the 100 km buffer area over the Chatham

Rise in similar water depths and habitats: sei (Balaenoptera borealis), southern right, blue

(Balaenoptera musculus) and humpback (Megaptera novaeangliae) whales. The Chatham

Rise is part of a migration corridor for these species between their northern breeding grounds

and their southern ocean feeding grounds. Sightings of baleen whales are rare in this dataset

so species that were observed beyond the 100 km buffer area over the Chatham Rise have

been commented on in order to increase sample size. One of these species, the southern

right whale, is listed as Nationally Endangered.

Figure 2-6: Distribution of all baleen whale sightings from DOC and Cawthorn datasets within the Chatham Rise study area. The 100 km buffer of the study area is indicated by the red box. Chatham Rock Phosphate Ltd. mineral extraction permitted area shown in red; benthic protected areas shown in pink.

2.2.1 Minke whale (Balaenoptera bonaerensis)



Minke whales were observed on four occasions from 1983 to 2003 within the 100 km buffer

study area. A total of nine individuals were observed in spring, summer and winter (Figure

2-6; Table 1-1). In addition to the study area sightings, a group of five individuals were

observed beyond the 100 km buffer area over the Chatham Rise in summer 1983. The

current best estimate of the number of the minke whale population in the Southern

hemisphere (60ºS to the non-navigable ice edge), derived from the International Whaling

Commission (IWC), is 760,000, with a 95% CI of 510,000 – 1,140,000. Minke whales

generally use the upper portions of the water column (< 300 m) and forage on a variety of

small myctophid fish and euphausiids, but may migrate over very deep water.


Minke whales are currently hunted by Japanese whalers in the Southern Ocean and take

approximately 1% a year of the current population estimate. This directed hunt means the

population already sustains anthropogenic pressure.

2.2.2 Blue whale (Balaenoptera musculus)

IUCN Threat Classification: Endangered

New Zealand Threat Ranking (Baker et al. 2010): Migrant

Due to extensive whaling effort, there are estimated to be fewer than 2,000 blue whales in

the southern hemisphere (Shirihai 2002). Blue whales are long-lived, slow reproducing

animals. During their migration between the summer feeding grounds in the Antarctic and the

equatorial waters where they spend the winter, blue whales are believed to pass through

New Zealand waters (Shirihai 2002). Blue whales typically forage on euphausiids in waters

less than 200 m, but may migrate over very deep water. No sightings of blue whales were

made within the 100 km buffer study area. However, two sightings of individual blue whales

have been recorded just west of the study area (Figure 2-6) in summer 1984 and autumn

1998 (Table 1-1).

2.2.3 Humpback whale (Megaptera novaeangliae)



Humpback whales in the southern hemisphere were significantly reduced by the whaling

industry, but the population is currently recovering (Suisted & Neale 2004). The International

Whaling Commission (IWC) point estimate of the southern hemisphere population of

humpback whales (south of 60ºS) is 42,000 with 95% CI 34,000-52,000. This is a

conservation estimate because it is restricted to waters south of 60ºS. The New Zealand

stock is possibly part of the East Australian stock which between 1981and 1996 had a rate of

population increase of about 12.4% with 95% CI 10.1-14.4%. Humpback whales travel along

the New Zealand coast between May and December as they migrate between their summer

feeding grounds in the Antarctic and their winter breeding grounds in the tropics, particularly

around Tonga (Shirihai 2002). Four sighting of five individuals were made beyond the 100

km buffer area over the Chatham Rise (Figure 2-6) in autumn and summer. The humpback

whale has a generalist diet, feeding on euphausiids and various species of small schooling

fish. Humpback whales generally use the upper portions of the water column (< 300 m), but

may migrate over very deep water..

2.2.4 Sei whale (Balaenoptera borealis)



Sei whales likely migrate past New Zealand as they travel south to Antarctic summer feeding

grounds and return north to warmer breeding waters in winter (Shirihai 2002). No sightings of

sei whales were made within the study area. However, one sighting of two individuals was

made approximately 100 km east of the study area in summer 1983 (Figure 2-6). Sei whales

generally use the upper portions of the water column (< 300 m) and forage on a variety of

small myctophid fish, euphausiids and squid, but may migrate over very deep water.


2.2.5 Southern right whale (Eubalaena australis)

IUCN Threat Classification: Least Concern

New Zealand Threat Ranking (Baker et al. 2010): Nationally Endangered

Southern right whales in New Zealand are considered nationally endangered due mainly to

whaling that dramatically reduced the population from about 27,000 animals (Jackson et al.

2011) to just 908 today (Carroll et al. 2011b). Protection of this species is critical as they are

long-lived and slow reproducing animals with a very small population. Southern right whales

are capital breeders that use energy stores accumulated at an earlier time to nurse calves

(Houston et al. 2007), with a strong migration cycle. This ecological strategy means these

whales spend the winter season calving and mating in coastal, protected waters, while the

remainder of the year the whales travel in offshore waters in search of dense, energetically

profitable prey aggregations in order to build up a blubber layer to support their energetic

needs during the calving and mating months.

The sheltered, winter calving grounds of southern right whales in New Zealand are relatively

well defined (Alexander et al. 2008, Carroll et al. 2011a, Patenaude & Baker 2001). The main

calving areas are at the sub-Antarctic Islands of the Auckland Islands and Campbell Island.

Southern right whales are slowly expanding their range or recolonizing calving grounds they

had been extirpated from around mainland New Zealand, with recent sightings in Fiordland,

Te Waewae Bay, in Otago and Wellington Harbours, and along the Kapiti Coast.

Outside the winter calving season (May-Sep) southern right whales remain in offshore waters

to forage. Little is known about their offshore distribution patterns, (Bannister et al. 1999,

Ohsumi & Kasamatsu 1986) but recent habitat modelling of 19th century whaling records

using boosted regression trees provided the first quantitative description of the offshore

habitat of southern right whales (Torres et al. 2011). Overall, the preferred offshore foraging

habitat of southern right whales in the eastern area of the Australasian region (130°W to

155°E, and 30°S to 55°S) was characterized by mean water temperature between the

surface and 200 m between 10 and 13 °C, mixed layer depth less than 40 m, chlorophyll

concentration above 0.2 mg/m3, and near the Sub-tropical front (Torres et al. 2011).

Southern right whales are large animals that feed on tiny prey so they must locate and

exploit dense aggregations. The dive pattern of right whales is optimized for exploiting

zooplankton aggregated in discrete layers, which includes rapid descents and ascents to

foraging depths to reduce transit time and maximize the duration of foraging time at depth

(Baumgartner et al. 2003). Little is known about the diet of southern right whales beyond

stomach contents of animals killed by whalers north of 50° S that documented copepod

(Calanus spp.) dominance (Tormosov et al. 1998).


Seasonal predictions of southern right whale distribution in the New Zealand region were

generated by Torres et al. (2011) based on habitat models of historical whaling data (Figure

2.7). The area of these spatial predictions includes the Chatham Rise, and although at a

larger scale (70 X 70 km) than the Chatham Rock Phosphate Ltd. permit area, provides

predictions of southern right whale habitat suitability and presence in the area. Few southern

right whales are expected to be in the Chatham Rise area during winter (when animals are at

coastal calving grounds) or spring. However, southern right whales do congregate along the

southern edge of the Chatham Rise during summer and autumn, where they forage on

copepod prey that aggregate here as a function of the Sub-tropical front. This habitat is

particularly important during the autumn period.

Only one sighting of a southern right whale was made in the Chatham Rise area,

approximately 100 km west of the study area in spring 1998 (Figure 2-6). No sightings of

southern right whales were made within the 100 km buffer study area. The lack of sightings

in the area does not indicate that southern right whales do not use this habitat because (1)

sightings are rare due to the small population size, and (2) no dedicated survey effort has

been conducted in the region.


Figure 2-7: Seasonal habitat prediction maps of southern right whales in the region around New Zealand, including over the Chatham Rise. Prediction maps derived from habitat models generated using historical whaling data and boosted regression trees (Torres et al. 2011). Resolution is 70 X 70 km. Colour ramp indicates high and low values of predicted sperm whale presence and are comparable between seasons. (a) Spring: September, October, November. (b) Summer: December, January, February. (c) Autumn: March, April, May. No prediction map for winter generated because whales on calving grounds. Black star indicates approximate location of CRP permit area.

2.3 Summary of cetacean habitat use and foraging patterns

In summary, 12 species and 1 species group (beaked whales) of cetaceans have been

recorded on the Chatham Rise near the Chatham Rock Phosphate Ltd. area of interest.

These species have a diverse range of habitat use patterns and foraging ecology that are

summarized in Table 2-1.


Table 2-1: General habitat use and foraging patterns of the 12 species and 1 species group of cetaceans recorded near the permit area.

Species Water column use while foraging Foraging patterns

Beaked whales Deep (~800-1000m); shelf edges Target deep water squid and fish

Blue whale (Balaenoptera musculus) Shallow (< 200 m) Filter feeder that targets euphausiids and small fish

Bottlenose dolphin (Tursiops truncatus) Shallow to mid (< 500m) Target small to mid-sized fish and squid associated with scattered mixed layer

Common dolphin (Delphinus spp.) Shallow to mid (< 500m) Target small to mid-sized fish and squid associated with scattered mixed layer

Dusky dolphin (Lagenorhynchus obscurus) Shallow to mid (< 500m) Target small to mid-sized fish and squid associated with scattered mixed layer

False killer whale (Pseudorca crassidens) Deep (~600-1000m); shelf edges Target deep water squid and fish

Humpback whale (Megaptera novaeangliae) Shallow (< 300 m) Filter feeder that targets euphausiids and small fish

Killer whale (Orcinus orca) Shallow to mid (< 500m); shelf edges Target fish, marine mammals, sharks, rays

Minke whale (Balaenoptera bonaerensis) Shallow (< 300 m) Filter feeder that targets euphausiids and small fish

Pilot whale (Globicephala spp.) Deep (~800-1000m); shelf edges Target deep water squid and fish

Sei whale (Balaenoptera borealis) Shallow (< 300 m) Filter feeder that targets euphausiids and small fish

Southern right whale (Eubalaena australis) Shallow (< 300 m) Filter feeder that targets euphausiids and small fish

Sperm whale (Physeter macrocephalus) Deep (~800-1000m); shelf edges Target deep water squid and fish


Table 2-2: Strandings in the Canterbury and Otago regions reported as 'collision/accident' in the Department of Conservation whale stranding

database.

Date Species Common name Region Location Description Lat Long

unknown Pseudorca crassidens False killer whale Otago Porpoise Bay, Waikawa Harbour -46.6483 169.1081

25/03/1987 Physeter macrocephalus Sperm whale Canterbury Claverly Beach, 12km south of Kaikoura -42.5987 173.4773

18/09/1992 Ziphius cavirostris Cuvier's beaked whale Canterbury Scarborough, Timaru -44.4356 171.2619

26/11/1994 Cephalorhynchus hectori Hector's dolphin Canterbury South New Brighton -43.5234 172.7379

5/09/1994 Physeter macrocephalus Sperm whale Canterbury Ohau point, 20km north of Kaikoura peninsula -42.2482 173.8302

1/09/1995 Phocoena dioptrica Spectacled Porpoise Otago Willsher Bay, north side of Kakora creek -46.3975 169.7818

20/04/1997 Lagenorhynchus obscurus Dusky dolphin Canterbury South Bay area Kaikoura -42.4164 173.6767

21/07/1998 Physeter macrocephalus Sperm whale Canterbury Waipapa Bay: Mangamaunu, Kaikoura -42.205 173.8761

7/01/1999 Lagenorhynchus obscurus Dusky dolphin Canterbury South Bay, Kaikoura -42.4293 173.6768

7/09/2002 Lagenorhynchus obscurus Dusky dolphin Canterbury Kaikoura -42.3733 173.9591

23/01/2008 Mesoplodon sp. Beaked whale Canterbury Okiwi Bay, Kaikoura -42.2179 173.862

2/11/2009 Balaenoptera sp. Baleen whale (possibly fin whale) Canterbury Lyttelton Harbour -43.6073 172.7175


3 Threats to cetaceans There are various anthropogenic impacts on cetaceans including ship strike, noise, habitat

degradation, entanglement, pollution, all of which are discussed in this section. However,

entanglement and pollution are unlikely impacts to cetacean due to the mining activities of

Chatham Rock Phosphate Ltd. on the Chatham Rise.

3.1 Ship strike

Vessel strikes on cetaceans are a very difficult issue to quantify and describe. Most cetacean

vessel strikes are unreported, either by intention to deceive managers or, more frequently,

because the event was unnoticed by the ship crew. Cetaceans that are hit by a vessel in

offshore waters either die and their carcass sinks or is scavenged, or are injured,

compromising their survivability. In both cases, no indication of the ship strike is perceived

and the event is not recorded. Occasionally carcasses of cetaceans struck by vessels are

discovered floating or stranded. It is from these sparse records that our knowledge cetacean

ship strikes is derived.

Laist et al. (2001) compiled all available data, historic and recent, on vessel strikes on the

great whales globally. Large whales are most vulnerable to ship strikes because they are

generally slower and less agile than small cetaceans such as dolphins, who frequently seek

out large vessels to bow ride. Evidence of ship collisions was found for 11 species (Laist et

al. 2001). Overall, fin whales (Balaenoptera physalus) were hit most frequently, but collisions

with northern and southern right whales, humpback whales, gray whales (Eschrichtius

robustus), and sperm whales were relatively common in some areas. Although all types and

sizes of vessels may hit whales, most lethal and serious injuries to whales are caused by

relatively large vessels (e.g., 80 m or longer; Laist et al. 2001). Of the collisions in which

whales were killed, 87% involved ships more than 80 m long.

The probability of a lethal injury (i.e., killed or severely injured) to a large whale is a function

of vessel speed at the time of the collision. Laist et al. (2001) found that most severe and

lethal injuries to whales caused by ship strikes appear to be caused by vessels traveling at

14 knots or faster. Vanderlaan & Taggart (2007) found the greatest rate of change in the

probability of a lethal injury to a large whale occurs between vessel speeds of 8.6 and 15

knots. Across this speed range, the chances of a lethal injury decline from approximately

80% at 15 knots to approximately 20% at 8.6 knots. Notably, it is only at speeds below 11.8

knots that the chances of lethal injury drop below 50% and above 15 knots the chances

asymptotically increase toward 100% (Vanderlaan & Taggart 2007). The US government has

implemented a speed restriction of 10 knots or less at certain times of year and in certain

locations to reduce ship strikes of northern right whales along the US east coast. Similarly,

scientists and managers are seeking speed restrictions of 10 knots in the Hauraki Gulf to

reduce ship strikes of Bryde’s whales (Balaenoptera edeni).

Ship collisions with whales are likely rare events in most parts of the world away from

habitats extensively used by whales. Therefore, vessel strikes on whales probably have a

negligible effect on the status and trend of most whale populations, but for very small

populations or discrete groups, ship strikes can have a significant effect. Examples of such

small populations in New Zealand include southern right whale and Bryde’s whale.


3.1.1 Review of known cetacean-vessel interactions in New Zealand waters, focused on east coast, South Island

The Department of Conservation whale stranding database (Department of Conservation

2012b) includes 66 records of cetacean strandings due to collisions. Ten of these events

occurred in the Canterbury region, and two were in the Otago region (Table 2-2). These

strandings consist of three sperm whales, three dusky dolphins, two beaked whales, and a

single false killer whale, spectacled porpoise (Phocoena dioptrica), Hector’s dolphin

(Cephalorhynchus hectori) and an unidentified baleen whale (possibly fin whale).

Unfortunately, no further details on the collisions or nature of the strandings are reported so

comments cannot be provided on the type of vessel, speed of vessel, or behaviour of animal.

Van Waerebeek et al. (2007) describe multiple reports of ship strike events with cetaceans in

New Zealand. These reports include Bryde’s whales in the Auckland region, a pygmy blue

whale (Balaenoptera musculus brevicauda) near Auckland, five sperm whales throughout the

country, a minke whale in Westland, various killer whales incidents (typically with smaller

vessels), a Gray’s beaked whale (Mesoplodon grayi) at Mahurangi harbour (north of

Auckland), an Andrew’s beaked whale (Mesoplodon bowdoini) stranded in the Chatham

Islands, a Hector’s beaked whale (Mesoplodon hectori) in the Hauraki Gulf, and an Arnoux’s

beaked whale (Berardius arnuxii) at Riverton, south coast of South Island. Additionally,

scientists studying southern right whales on their breeding grounds in the Auckland Islands

reported in July 2012 witnessing a whale that had been struck by a ship - evidenced by the

succession of scars across its back from the ship’s propeller (Pers.comm., Will Rayment,

University of Otago).

3.2 Noise

Cetaceans are acoustically active animals as sound is the optimal form of communication

and perception in the marine environment. Therefore, cetaceans are particularly sensitive to

increased noise within their environment. Anthropogenic noise in oceans can cause death,

displacement from preferred habitats, impede foraging behaviour and success, lower prey

availability, mask communication, increase stress, increase energetic demands, and alter

acoustic patterns (Weilgart 2007). Also of concern are the cumulative effects of multiple

sources of anthropogenic sound in the marine environment (Ellison et al. 2012).

Cetacean responses to noise fall into three main categories: behavioural, acoustic and

physiological (Nowacek et al. 2007). Behavioural responses include changes in surfacing,

diving, distribution and heading patterns. Acoustic responses include changes in type or

timing of vocalizations relative to the noise source. And physiological responses include

auditory threshold shifts and ‘stress’ such as acute injuries and death.

It has been demonstrated that increased background noise can alter habitats of cetaceans

by masking communications for species that rely on sound to mate, feed, avoid predators,

and navigate (Clark et al. 2009, Ellison et al. 2012). Low-frequency ocean noise has been

shown to be a threat to baleen whales which are low-frequency specialists (Clark et al.

2009). Additionally, detrimental effects to delphinids, which typically use mid to high

frequencies for acoustics, have been documented (Jensen et al. 2009). Cetacean deaths

have been attributed to mid-frequency sonar (Parsons et al. 2008).

Documented marine mammal sound production characteristics as compiled by Wartzok &

Ketten (1999) are presented in Appendix A (section 8.1), which includes the type of sound


made by each species of marine mammal, its frequency range, source level, and references

for the information. Appendix B (section 8.2) illustrates underwater audiograms for

odontocetes and pinnipeds taken from Wartzok & Ketten (1999). No audiogram was provided

for mysticetes.

3.3 Habitat degradation

Like other animals, cetaceans may have preferred locations in which they spend the majority

of time or where they engage in particular important life history activities such as giving birth,

calf rearing, or feeding. The multiple physical and oceanographic features that characterize

these locations form the habitat of a species or local population. Human activities can

impinge upon the lives of cetacean if they damage or destroy these habitats that are

important to them.

Habitat pressures upon cetaceans from anthropogenic influences may be grouped into five

categories: (1) physical damage to their environment; (2) contamination from chemical

pollutants; (3) direct removal of important prey through fisheries; (4) disturbance from human

activities either by the introduction of sound into the environment or through ship strikes; and

(5) physical and oceanographic effects from global climate change (Evans 2009, Kemp

1996).

3.4 Entanglement

Cetaceans are prone to entanglement in fishing gear, particularly gill nets. Gill nets by design

are mostly transparent in water and do not backscatter acoustic signals to echolocating

cetaceans. The appendages of cetaceans (pectoral fins and flukes) get caught and tangled

in the nets, which often leads to drowning because the individual cannot reach the surface to

breath. A global assessment of marine mammal bycatch yielded an annual estimate of

653,365 marine mammals, comprising 307,753 cetaceans and 345,611 pinnipeds (Read et

al. 2006). Most of the world’s cetacean (84%) and pinniped (98%) bycatch occurs in gill-net

fisheries (84%). Cetacean entanglement can also occur in other gear. Whales entangle, and

subsequently drown, in crab pot lines (Knowlton & Kraus 2001). Whales also become

entangled is submarine cables, particularly sperm whales (Heezen 1957).

3.5 Pollution

Environmental contaminants are a serious concern for cetaceans. Many human produced

chemicals bioaccumulate in cetaceans, meaning that animals absorb these chemicals at a

rate faster than they are lost. Predatory animals, such as cetaceans, acquire the lifetime

accumulation of chemicals of the animals they eat. This leads to biomagnification, whereby

the concentration of chemicals increases greatly at every step in the food chain, and top

predators end up with extremely high levels (Borrell 1993, Law et al. 2012). Because baleen

whales feed on planktonic crustaceans, and are thus situated lower in the food web, their

tissue concentrations of pollutants are almost invariably lower than those in the top-predator

toothed whales living in the same ecosystem.

The main environmental toxins that are currently a concern for populations of marine

mammals are known as persistent organic pollutants (POPs) and include PCBs, PBDE’s and

dioxins and furans (Borrell 1993, Reijnders et al. 2009). Pollutants can also include oil-

pollution derived substances, marine debris, metals, sewage-related pathogens, excessive

amounts of nutrients causing environmental changes, and radionuclides.


High concentration of certain compounds in the tissues of these animals has been

associated with organ anomalies, impaired reproduction and immune function, and as a

consequence of the latter, with the occurrence of large die-offs among seal and cetacean

species (Johnston et al. 1996, Reijnders et al. 2009). Increased exposure to pollution might

manifest through high tissue pollutant concentrations in individuals, and changes in a

population’s biological parameters such as physiological condition and changes in

reproductive or mortality rates (Reijnders 1996, Reijnders et al. 2009). Increased ocean

pollution can also impact cetaceans through prey depletion, habitat disturbance, and

increase susceptibility to disease.

4 Potential impacts on cetaceans by Chatham Rock Phosphate Ltd. mining activities

4.1 Ship strike

No data at a sufficient spatial or temporal resolution on shipping traffic and cetacean

distribution in the Chatham Rise area are available to assess strike rates or likelihood of

collisions. Although the density of both ships and cetaceans cannot be resolved at this time,

results from other areas show that vessel speed is a critical component to reduce significant

injury and mortality to cetaceans. For context, in the 2008 calendar year, 123 fishing vessels

performed 18,568 fishing events in the Chatham Rise fisheries management area (FMA3:

approximately 42.1° to 46° S, 176° E to the EEZ boundary). The presence of additional

vessels on the Chatham Rise from mining activities by Chatham Rock Phosphate Ltd. is

unlikely to substantially increase the risk of ship strike to cetaceans in the area.

Although the data compiled in this report are insufficient to draw conclusions on locations or

species most prone to ship strikes within New Zealand, the data do establish that collisions

between vessels and cetaceans occur all around New Zealand and involve a variety of

species. However, based on the slow travel speed of the dredging vessel while operating (1

m/s), it is unlikely that a collision or harmful interaction with a cetacean would occur,

especially with agile species including all odontocets. However, baleen whales are less agile

and therefore more prone to collisions. For instance, a southern right whales may not notice

a vessel until close contact is made. Southern right whales are slow moving and less agile

than most other cetaceans, which makes them particularly vulnerable to ship-strikes in many

areas of the world (Kemper et al. 2008, Knowlton & Brown 2007, Van Waerebeek et al.

2007). It has been documented that northern right whales (Eubalaena glacialis) do not

respond behaviourally (evade ships) to vessel noise (Nowacek et al. 2004, Terhune &

Verboom 1999). Yet, a collision or harmful interaction with a southern right whale remains

unlikely due to the slow travel speed of the dredging vessel while operating. However,

transiting vessels to and from the mining area should take precautions not to strike whales,

particularly around the southern edge of the Chatham Rise during summer and autumn when

this habitat is important for foraging southern right whales (see section 2.2.5).

4.2 Noise

Noise emitted from the dredging and disposal system are likely to disturb cetaceans within a

small scale area (< ~20 km), over a short period of time, yet actual impacts will be based on

the acoustic sensitivity of each species (see Appendix A and B – sections 8.1 and 8.2) and

the intensity and frequency of noise emitted. The expected short-term and local impacts of

noise on cetaceans due to the mining operation may cause animals to temporarily leave an


area or mask their acoustic capabilities requiring animals to expend more energy to make

louder or more frequent calls.

Various studies have indicated negative effects of anthropogenic noise on cetacean species

that have occurred in the Chatham Rock Phosphate Ltd. area of interest. Sperm whales are

vulnerable to noise pollution (Miller et al. 2009, Thode et al. 2007) as they use echolocation

for navigation, foraging and communication. A study documented reduced pilot whale

communication range (up to 58%) as a function of small vessel noise from vessels travelling

at 5 knots within 50 m (Jensen et al. 2009). Previous studies have documented changes in

the acoustic behaviour of killer whales in response to increased anthropogenic noise (Holt et

al. 2011, Holt et al. 2009). Beaked whales appear to be especially vulnerable to acoustic

noise, with multiple incidents of mortality potentially caused by anthropogenic activity (Barlow

& Gisiner 2006, Cox et al. 2006). Many studies have documented impacts on right whales

from increased vessel noise including habitat displacement, behavioural changes, increased

stress levels, and the frequency and intervals of acoustic calls (Hatch et al. 2012, Parks et al.

2011, Rolland et al. 2012). Various studies have demonstrated impacts on blue whales and

humpback whale behaviour and communication patterns due to increased anthropogenic

noise (Clark et al. 2009, Di lorio & Clark 2010, Melcon et al. 2012).

4.3 Habitat degradation The impacts of the proposed mining operations on cetacean habitat over the Chatham Rise may include physical damage, pollution (see Sections 3.5 and 4.5), and increased noise (see Sections 3.2 and 4.2), however the magnitude of these impacts are expected to be small-scale, short-term or unlikely. Increased sediment or a disturbed benthic environment may impede the foraging success of some cetaceans through decreased sensory capabilities (visual and acoustic), and/or dispersal of prey from typical foraging habitats. Even if a species of cetacean does not feed in the Chatham Rock Phosphate Ltd. mineral permit area, areas of foraging habitat surrounding the Chatham Rise to the north and south of the permit area may be affected as a function of plume propagation, concentrations and transport.

Of particular concern may be increased sediment or a disturbed environment along the

southern edge of the Chatham Rise due to Chatham Rock Phosphate Ltd. mining activities

that may impede the foraging success of southern right whales. If sediment plumes extend to

this area, important prey aggregations for these endangered whales may be disrupted or

whales may experience decreased sensory capabilities to detect the prey patches.

4.4 Entanglement

Given the proposed dredging system, the entanglement of a cetacean in the lines between

vessel and dredge is unlikely due to (1) the thickness of the lines, and (2) the lines remaining

taught in order to move the dredge along the seafloor. Cetaceans will likely be able to

perceive the lines visually and if physical contact is made, it is unlikely that an entanglement

will occur.

4.5 Pollution Given the large ranges of cetaceans and the small-scale nature of this mining project, the impact of pollution on cetaceans is likely to be negligible. However, if an oil spill or other chemical release were to occur due to the mining operations, these toxins could bioaccumulate in cetaceans and have long-term effects on individuals and populations.


5 Summary and Conclusions Observations of cetaceans in the Chatham Rise area are dominated by sperm and pilot

whales that rely on this habitat as a foraging ground. Additionally, various species of

dolphins, baleen whales and beaked whales including the endangered killer whale and

southern right whale use and transit through this area. Potential impacts from the Chatham

Rock Phosphate Ltd. mining operation on cetaceans are will probably be limited to disturbed

habitat and acoustic disturbance, both of which are likely to be short term and localized

impacts. Vessel strikes on cetaceans are unlikely to occur during the dredging operation due

to the slow speed of the vessel, but precautions should be taken while in transit to avoid

collisions.

6 Acknowledgements Review comments were received from Martin Cawthorn and incorporated into the report.

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Baker, C.S. (2008). Individual identification, regional movements and genetic

differentiation of the mainland New Zealand southern right whale population,

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Amos, B.; Schlotterer, C.; Tautz, D. (1993). Social structure of pilot whales revealed

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http://dx.doi.org/10.1126/science.8480176.

Baker, A.N.; Madon, B. (2007). Bryde's whales (Balaenoptera cf. brydei Olsen 1913)

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8 Appendices

8.1 Appendix A: Marine mammal sound production characteristics (Wartzok & Ketten 1999)







8.2 Appendix B: Underwater audiograms for (a) odontocetes and (b) pinnipeds (Wartzok & Ketten 1999)

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