EFFECT OF CLIMATE CHANGE ON FISH PRODUCTION IN THE … · • A climate-related warming of lakesand rivers has been observed over recent decades. Cont. ... situated in West Africa,

EFFECT OF CLIMATE CHANGE ON FISH PRODUCTION IN THE VOLTA LAKE.

BY:

EMMANUEL T.D MENSAH (CSIR-WRI, GHANA)

H.R. DANKWA (CSIR-WRI, GHANA)

L.L. TORBEN (AARHUS UNIV., DENMARK)

RUBY ASMAH (CSIR-WRI, GHANA)

Collaborators: CSIR-Water Research Institute

Aarhus University, Denmark

Sponsor: DANIDA

Duration: 3 years (2014 – 2017)

VOLTRES PROJECT – WP 3

INTRODUCTION • Fisheries, an important sector of the economy: 4.5% of Agric. GDP (2014), 60% animal

protein consumption

• Volta Lake, an important source of freshwater, contributes 80% of inland catches and houses80% of aquaculture production

• Lake is rich in fish fauna: 132 different species dominated by Chrysichthys, Tilapia andSynodontis species

• Total inland catches from 1969-2015 shows an upward trend, with a decreasing CPUE due toincreasing effort (number of canoes and fishermen)

• Environmental factors (Temp., nutrient availability) can also result in changes in fishcomposition, catches, nutrient loadings, phenological shift

• A climate-related warming of lakes and rivers has been observed over recent decades.

Cont.

• The climatic condition in the Volta Basin, situated in West Africa, is likely to become warmer as the rest of Africa.

• Temperatures in the Lake region are expected to rise between 1°C and 1.5 °C by middle of the 21st century

• Ghana is listed among the countries that are most vulnerable to climate change because of the high vulnerability of the country’s fishery sector to climate change

Determining climate change impact of fish production in the Lake and establishing appropriate strategies for adaptation are key to ensuring sustainable exploitation, improvement of the socio-economic status of local communities thereby assuring food security.

OBJECTIVES

To determine the catch composition, species diversity and relationship in seasonal trends incatch and environmental parameters in Stratum III of the Volta Lake

To determine the effects of seasonal environmental changes on cage fish production inStratum II of the Volta Lake

To map out food preferences of some major fish species of economic importance in StratumIII of the Volta Lake

To make prediction of future fish stocks of Lake Volta using the EcoPath model in the face ofchanging climate.

Volta Lake

Located between 1° 30´W and 0° 20´ N and 9°10´ N

Surface area, 8,500 km2; shoreline, 4,880 km

Max and mean depth of 75 m and 14 m respectively

Major tributaries: White Volta, Black Volta, Rivers Oti, Afram

METHODOLOGY

Fig. 1: Map of study site

THEME 1: SEASONAL CHANGES IN ENVIRONMENTAL VARIABLES AND FISH CATCHES IN STRATUM III OF THE VOLTA LAKE, GHANA

• Monthly sampling of fish catch using gill nets in Stratum III of the lake: Sept. 2014 - Aug. 2016

• Gear type: 2 different types: mono filament, 12 (between 38.1 mm – 190.5 mm) and multi filament, 6(between 12.5 mm – 40 mm) of length 25 m and 4 m depth

• Fishes caught sorted, identified, grouped into families and morphometric measurements taken

• Environmental parameters: water temp., DO, TDS, nutrients (ammonia, phosphates) and chlorophyll a takenduring time of sampling

• Species sampled into and 3 designated hydrological seasons: dry season (Dec–Mar); major wet season(Apr–Jul) and minor wet season (Aug-Nov)

• Data gathered analyzed: diversity indices, ANOVA to describe and compare seasonal catches and PCA toestablish relationship with species abundance and environmental parameters

PRELIMINARY RESULTSA total number of 1557 individual fish samples of 42 species belonging to 13 families recorded in the sampling

Fig. 1: Fish catch composition in numbers (a) and weight (b) sampled at Kpando Torkor, September, 2014 to August, 2016

Chart1

Alestidae

Bagridae

Cichlidae

Claroteidae

Mochokidae

Mormyridae

Others

14.1297366731

5.6518946692

28.9659601798

43.0314707771

1.5414258189

4.6885035324

1.9910083494

sepaug 16

Alestes baremozeAlestidae


































































Alestes dentexAlestidae





































































Auchenoglanis occidentalisClaroteidae




Babrus bajadBagridae

Bagrus bajadBagridae

































































Bagrus bayadBagridae

Bagrus docmakBagridae





















Barbus sppCyprinidae

Brycinus leuciscusAlestidae







Brycinus macrolepidotusAlestidae













































Brycinus nurseAlestidae









Chiloglanis occidentalisMochokidae

Chiloglanis occidentalisMochokidae

Chromidotilapia guntheriCichlidae








































Chrysichthys auratusClaroteidae





























































































































































































































Chrysichthys maurusClaroteidae
































































































































































Chrysichthys nigrodigitatusClaroteidae





























































































































































































































































































Citharinus latusCitharinidae

Clarias anguilarisClaridae

Hemichromis bimaculatusCichlidae
















































Hemichromis fasciatusCichlidae






































































































































Hydrocynus forskaliiAlestidae






















Hydrocynus vittatusAlestidae

Hydrocynus vittatusAlestidae

Labeo coubieCyprinidae

Labeo parvusCyprinidae

Labeo parvusCyprinidae

Lates niloticusLatidae

Leptocypres niloticusCyprinidae

Mormyrops anguilloidesMormyridae




Mormyrops angulloidesMormyridae



























Mormyrus rumeMormyridae










Odaxothrissa mentoClupeidae


















Oreochromis niloticusCichlidae

Oreochromis niloticusCichlidae

Pelonula leonensisClupeidae

Petrocephalus boveiMormyridae
































Sarotherodon galilaeusCichlidae

Sarotherodon galilaeusCichlidae

Sarotherodon galileausCichlidae




Schilbe intermediusSchilbeidae

Schilbe intermediusSchilbedae

Steatocranus irvineiCichlidae















































































































































Synodontis eupterusMochokidae

Synodontis nigrataMochokidae

Synodontis nigritaMochokidae



Synodontis oceiliferMochokidae

Synodontis oceiliferMochokidae

Synodontis ocelliferMochokidae











Synodontis schallMochokidae

Synodontis velliferMochokidae



Tetraodon lineatusTetraodontidae

Tetraodon lineatusTetraodontidae

Tilapia dagetiCichlidae


































Tilapia guineensisCichlidae

Tilapia zilliiCichlidae











































Sheet2

SpeciesFamilyNo.

Alestes baremozeAlestidae664.24

Alestes dentexAlestidae694.43

Auchenoglanis occidentalisClaroteidae40.26

Babrus bajadBagridae674.30

Bagrus docmakBagridae211.35

Brycinus leuciscusAlestidae70.45

Brycinus macrolepidotusAlestidae452.89

Brycinus nurseAlestidae90.58

Chromidotilapia guntheriCichlidae402.57

Chrysichthys auratusClaroteidae22114.19

Chrysichthys maurusClaroteidae16010.28

Chrysichthys nigrodigitatusClaroteidae28518.30

Clarias anguilarisClaridae10.06

Hemichromis bimaculatusCichlidae483.08

Hemichromis fasciatusCichlidae1348.61

Hydrocynus forskaliiAlestidae221.41

Hydrocynus vittatusAlestidae20.13

Labeo coubieCyprinidae10.06

Labeo parvusCyprinidae20.13

Lates niloticusLatidae10.06

Leptocypres niloticusCyprinidae10.06

Mormyrops anguilloidesMormyridae311.99

Mormyrus rumeMormyridae100.64

Odaxothrissa mentoClupeidae181.16

Oreochromis niloticusCichlidae20.13

Pelonula leonensisClupeidae10.06

Petrocephalus boveiMormyridae322.06

Sarotherodon galileausCichlidae60.39

Schilbe intermediusSchilbeidae20.13

Steatocranus irvineaCichlidae1439.18

Synodontis eupterusMochokidae10.06

Synodontis nigrataMochokidae40.26

Synodontis ocelliferMochokidae130.83

Synodontis schallMochokidae10.06

Synodontis velliferMochokidae30.19

Tetraodon lineatusTetraodontidae20.13

Tilapia dagetiiCichlidae342.18

Tilapia guineensisCichlidae10.06

Tilapia zilliiCichlidae432.76

Barbus sppCyprinidae10.06

Chiloglanis occidentalisMochokidae20.13

Citharinus latusCitharinidae10.06

42 species1557

Sheet3

SpeciesFamilyNo.wt.FamilyAbundance% Abundancewt%Rel abundance

Alestes baremozeAlestidae664.249719.8Alestidae22014.1332297.232.1014.13

Alestes dentexAlestidae694.4310187.6Bagridae885.6512880.212.805.65

Brycinus leuciscusAlestidae70.45122Cichlidae45128.9717973.817.86

Brycinus macrolepidotusAlestidae452.895107.5Claroteidae67043.0318038.417.93

Brycinus nurseAlestidae90.58437.3Mochokidae241.541483.91.47

Hydrocynus forskaliiAlestidae221.416503.4Mormyridae734.6911988.611.91

Hydrocynus vittatusAlestidae20.13219.6Others311.995959.75.92

22014.13100621.8

Babrus bajadBagridae674.3010298.1FamilyAbundance ScoreInterpretation

Bagrus docmakBagridae211.352582.1Alestidae220Abundant

885.6518946692Bagridae88Few

Chromidotilapia guntheriCichlidae402.57836Cichlidae451Dominant

Hemichromis bimaculatusCichlidae483.08540.4Claroteidae670Dominant

Hemichromis fasciatusCichlidae1348.614100.9Mochokidae24Rare

Oreochromis niloticusCichlidae20.13442.9Mormyridae73Few

Sarotherodon galileausCichlidae60.391075.6Others31Rare

Steatocranus irvineiCichlidae1439.182785.5

Tilapia dagetiCichlidae342.183196.4

Tilapia guineensisCichlidae10.06167.5

Tilapia zilliiCichlidae432.764828.6

45128.97

Auchenoglanis occidentalisClaroteidae40.261172.8

Chrysichthys auratusClaroteidae22114.194215.4

Chrysichthys maurusClaroteidae16010.284314.4

Chrysichthys nigrodigitatusClaroteidae28518.308335.8

67043.0314707771

Odaxothrissa mentoClupeidae181.16193.4

Labeo coubieCyprinidae10.061000

Labeo parvusCyprinidae20.13103.9

Leptocypres niloticusCyprinidae10.0614.2

40.2569043031

Lates niloticusLatidae10.0624.2

Synodontis eupterusMochokidae10.0616.4

Synodontis nigrataMochokidae40.2699

Synodontis ocelliferMochokidae130.83535.3

Synodontis schallMochokidae10.0656.7

Synodontis velliferMochokidae30.1982.1

Chiloglanis occidentalisMochokidae20.13694.4

241.54

Mormyrops anguilloidesMormyridae311.991825.6

Mormyrus rumeMormyridae100.649809.1

Petrocephalus boveiMormyridae322.06353.9

734.6885035324

Schilbe intermediusSchilbeidae20.1341.1

Tetraodon lineatusTetraodontidae20.13135.5

Pelonula leonensisClupeidae10.068.3

Clarias anguilarisClaridae10.06525

Barbus sppCyprinidae10.0614.1

Citharinus latusCitharinidae10.063900

Sheet3

Sheet1

Sheet4

Sheet5











Alestes baremozeAlestidae17822977




























































Alestes dentexAlestidae205262131





































































Bagrus bajadBagridae11716721.2


Bagrus bajadBagridae16023551













































Bagrus BayadBagridae297402326.5


Bagrus BayadBagridae230334162





Bagrus bayadBagridae10224080.9

Bagrus bayadBagridae18626286
























Bagrus docmakBagridae210295124









Barbus sppCyprinidae8010514.1














Brycinus macrolepidotusAlestidae72948
























































Chromidotilapia guntheriCichlidae8811125




































Chrysichthys auratusClaroteidae12114931









































































































































































































Documents

EFFECT OF CLIMATE CHANGE ON FISH PRODUCTION IN THE … · • A climate-related warming of lakesand rivers has been observed over recent decades. Cont. ... situated in West Africa,