Possible impact of Climate Change on the fishery industry

in Sri Lanka

P.R.T. CumaranatungaDept. of Fisheries & Aquaculture

Faculty of Fisheries and Marine Sciences & Technology

University of Ruhuna,Matara, Sri Lanka

Sri Lanka

Vulnerable areas due to sea level rise

Annual minimum air Temperature anomaly trend in Nuwara-Eliya

y = 0.02x - 1.6757

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Annual rainfall variability in Ratnapure

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Observations on Temperature & Rainfall

Impact of global warming on the Physicochemical parameters that

would affect the distribution & migration of tuna• Increase in temperature of water

• Change the horizontal & vertical distribution of global water temperatures

• Deepen the thermocline, which indicates that mixing of surface water layers spreads down to deeper depths.

• Rise in sea level

• Change the salinity distribution

• Change thermohaline circulations (vertical & horizontal current patterns)

• Affect the El Ninno Southern Ossilation (ENSO)

• Changes in rainfall

Thermohaline circulation caused by heating in lower latitudes & cooling in

higher latitudes

Shiftingdue to global warming

Polar ice

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we

llin

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wn

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Reduction in polar ice

Temperature gradient

& thermocline

in oceans

Expected deepening of thermocline due to global warming

Ocean stratification with respect to Temperature salinity & density and its possible directions of shifting due to

global warming

Vertical profile of selected physico-chemical

parameters in the ocean

O2 m

g L

-1

Global current pattern under normal conditions

•Warm srface currents•Cold surface currents

Up welling areas & fishing grounds

El ninno condition(ENSO)

Sea surface temperature anomalies in November 2007 showing La Niña conditions.

Blue- Temperature below averageRed- Temperature above average

Effect of global warming on behaviour & biology of

marine fish

Effects of increased temperatures on biology fish

• Since fish are cold blooded, when the surrounding water warms up, metabolism speeds up• Digest food more rapidly,

• Grow more quickly

• Have more energy to reproduce.

• But fish need more food and more oxygen to support this higher metabolism.

• Warmer fish tend to mature more quickly,

• This speedy lifestyle is often a smaller body size and a smaller brood.

• At higher temperatures sex determination will be affected (e.g. more females)

Impacts of global warming on habitats & behaviour of

fish• Expansion and/or contraction of suitable habitats (e.g. coral reefs, sea grass beds, mangroves, etc.)

• Shifts in the distribution of fish stocks throughAlteration or reduction of feeding grounds

Reduction in breeding grounds

Changes in migratory circuits that connect life stages

Affecting successful completion of the life cycle

Affecting successful recruitment

• Climate is a major factor affecting the productivity of key species in world fisheries.

• Changes in commercially and ecologically important marine fish species at organismal-level & population-level

– Growth– reproductive success – Mortality– Habitat

Impact of Global warming on Impact of Global warming on fisheriesfisheries

Impacts of decline of fish stocks on other important

matters(for Sri Lanka)

• Declines in fisheries will have massive impacts on – Commercial fishing,– Tourism– Biodiversity.

Possible adaptations of fish due to global warming

• Individual species or populations may build capacity to adapt to changes in important abiotic and biotic factors.

• Adaptations could include

– changes in the important life history events (e.g., migration, spawning)

and/or

– physiological changes (e.g., thermal reaction norms of key traits such as growth, increased tolerance to lowered pH/ocean acidification).

• As global warming continues, the pressure on fish populations will increase due to following

– Overfishing

– Pollution

– habitat loss

• Although slightly warmer water could be tolerated by man, its effect on fish and aquatic ecosystems, and ultimately on the global food supply and economic stability, could be severe.

Other impacts

SDA-Specific dynamic action

TemperatureoC

Global warming will continuously change the

habitats of fish • Many fish that cannot find a local

solution are already heading towards the poles as the water becomes too warm.

• Naturally, when fish find themselves in hot water, they head out in search of cooler locales.

• As global temperatures rise, some fish may be able to shift locally – by moving deeper or by heading upriver towards cool headwaters.

Problems faced by fish due to migration to warm waters

• Fish that can tolerate heat will become much more common.

• The fish that stay around will also have to deal with new species that enter in to their niche

How will fisheries change?• Fisheries resources may become less

predictable as extreme weather hits more often.

• Events like the El Niño might cause a greater impact on warm water fisheries and reef fisheries.

• Many fisheries resources will permanently shift location as water temperatures rise.

• Large, commercial fleets that can follow the fisheries may not be as strongly affected as local, small-scale fishermen, who will have to adapt their gear and methods, travel further, and fish longer to continue providing enough food for their families and local markets.

Impact of Global warming on tuna & bill fish & their fishery

Why the abundance of tuna species has changed in a given

time? • Three categories of factors:

–factors related to changes in fishing techniques that cause changes in species catchability (e.g., changing the depth exploited by the longline),

–environmental (climate-linked) factors inducing spatial changes in the distribution and movements of fish, both in the vertical and horizontal dimensions (e.g., in relation to the depth of the thermocline, or the seasonal or ENSO-related extension of warm waters)

–Real changes in abundance of the stock, with low or high levels of recruitment, in relation either to an environmental change or to the size of the spawning stock biomass (stock-recruitment relationship).

Note: that heart rate follows the change in water temperature, not muscle temperature. Cardiac output (data not shown) follows heart rate because of tunas’ limited ability to increase stroke volume.

Effect of an abrupt change in water temperature (25 to 15° C) on heart rate in a yellowfin tuna.

Distribution of tunas and tuna-like fish in the water

Biological characteristics of tuna in FAO-Fisheries and Aquaculture Departmenthttp://www.fao.org/fishery/topic/16082/en#Distribution

Species Latin Name Ocean T(mn) T(mx) PreferenceNorthern Bluefin Thunnus thynnus A, 7.63 26.17 20.84Southern Bluefin Thunnus maccoyii A,P,I 7.42 22Pacific Bluefin Thunnus orientalis P,I 6.98 24 18.5Bigeye tuna Thunnus obesus A,P,I 9.25 26.45 21.56Yellowfin tuna Thunnus albacares A,P,I 16.35 27.73 23.1Albacore tuna Thunnus alalunga A,P,I 11.29 23.9 22.5Skipjack tuna Katsuwonus pelamis A,P,I 16.63 29.47 24.25Kawakawa Euthynnus affinis P,I 16.5 30.5Slender tuna Allothunnus fallai A,P,I 15.5 19Striped Bonito Sarda orientalis P,I 14 23Atlantic bonito Sarda sarda A, 12 27Eastern pacific bonito Sarda chiliensis chiliensis P, 18.8 30.5Little tunny Euthynnus alletteratus A, 18 30Swordfish Xiphias gladius A,P,I 8.89 27.86 18Indo-pacific blue marlin Makaira mazara P,I 19.75 29.05Atlantic blue marlin Makaira nigricans A, 20.68 30.05 30White marlin Tetrapturus albidus A, 21.33 27.57 24Black marlin Makaira indica A,P,I 16.17 30.17Striped marlin Tetrapturus audax P,I 16.82 25.49 23.2Atlantic Sailfish Istiophorus albicans A, 19.2 27.9 21Pacific Sailfish Istiophorus platypterus P,I 20.5 27.85 26.68

Temperature (oC) Tolerance of Tuna & billfish species

Bracketed numbers represent the number of sources which support the data. Boyce Daniel (2006). Effects of water temperature on the global distribution of tuna and billfish. Dalhousie University Halifax, Nova Scotia

Ambient water temperature tolerances and preferences for 21 species of tuna and billfish

Ambient water temperature tolerances and preferences for larvae, juveniles & adults of tuna & billfish

Impact of Temperature on Species richness with respect to tuna & bill fish

Impact of Temperature on Species richness with respect to tuna &

bill fish in Atlantic, Pacific & Indian Oceans

Number of tuna in a sample of 50 individuals

Distribution of Temperate & Tropical Tunas

Biological characteristics of tuna in FAO-Fisheries and Aquaculture Departmenthttp://www.fao.org/fishery/topic/16082/en#Distribution

 

• Tropical tunas: skipjack and yellowfinI• Intermediate tunas: bigeye• Temperate tunas: albacore, Pacific bluefin, Atlantic bluefin and southern bluefin

 

Distribution of Oceanic & Neritic Tunas

Biological characteristics of tuna in FAO-Fisheries and Aquaculture Departmenthttp://www.fao.org/fishery/topic/16082/en#Distribution

3 of the 8 species of Thunnus are found worldwide except in the Arctic Ocean. Most bonitos and little tunas (Euthynnus spp.) are primarily neretic, ie coastal fishes, but the distribution of individual species is often widespread. The frigate and bullet tunas (Auxis spp.) are probably both oceanic and coastal (Olson and Boggs, 1986).

Impact of global warming on the fisheries of the

Indian Ocean• If the temperature of Indian Ocean

increases, there is a risk of losing the important fishing grounds

• Important fisheries such as tuna fisheries will suffer because tuna fish stocks may shift their migratory circuits towards sub tropicasl or temperate regions

Seasonal variation of current pattern in the Indian Ocean

February March

August September

Seasonnal variations in surface temperatures in the Indian Ocean

November

SeptemberMarch

JulyJanuary

May

CPUE distribution pattern of yellowfin tuna in the Indian Ocean

Pei-Fen Lee, I-Chin Chen and Wan-Nien Tseng, Distribution Patterns of Three Dominant Tuna Species in the Indian Oceanhttp://proceedings.esri.com/library/userconf/proc99/proceed/papers/pap564/p564.htm

January April

July October

Peak abundance of tuna species in the Indian

Ocean

Pei-Fen Lee, I-Chin Chen and Wan-Nien Tseng, Distribution Patterns of Three Dominant Tuna Species in the Indian Oceanhttp://proceedings.esri.com/library/userconf/proc99/proceed/papers/pap564/p564.htm

Peak abundance regions for albacore, bigeye and yellowfin tunas in the

Indian Ocean

. All specioes 0; Albacore 1-2, bigeye tuna1-3, yellowfin tuna1-4 Albacore 3-4, bigeye tuna4-6, yellowfin tuna5-8 Albacore 5-8, bigeye tuna7-10, yellowfin tuna9-11

Pei-Fen Lee, I-Chin Chen and Wan-Nien Tseng, Distribution Patterns of Three Dominant Tuna Species in the Indian Oceanhttp://proceedings.esri.com/library/userconf/proc99/proceed/papers/pap564/p564.htm

Effect of Sea surface Temperature on the distribution of Yellowfin tuna

Pei-Fen Lee, I-Chin Chen and Wan-Nien Tseng, Distribution Patterns of Three Dominant Tuna Species in the Indian Oceanhttp://proceedings.esri.com/library/userconf/proc99/proceed/papers/pap564/p564.htm

Effect of chlorophyll concentration on the distribution of Yellowfin tuna

Pei-Fen Lee, I-Chin Chen and Wan-Nien Tseng, Distribution Patterns of Three Dominant Tuna Species in the Indian Oceanhttp://proceedings.esri.com/library/userconf/proc99/proceed/papers/pap564/p564.htm

Possible impacts of global warming on Possible impacts of global warming on the coastal biodiversity and fisheries the coastal biodiversity and fisheries

Bleaching of corals (in thermo-sensitive corals)

Reduction of sea grass & algal beds with low temperature tolerance

Loss of feeding and breeding grounds for fish & other economically important coastal and marine organisms

Alteration of migratory circuits of highly migratory & economically important fish species (eg. Tuna, bill fish, etc.)

Reduction of coastal land area available for aquaculture

Reduction of beaches & sand dune ecosystems due to coastal inundation & erosion

Action neededAction neededIdentify the most vulnerable & easily adapted species to climate changes.

Temperature and salinity tolerant species should be promoted for aquaculture purposes.

Identify the changes in migratory circuits of tuna, bill fish, etc. through biotechnological & satellite remote sensing techniques.

Introduction of coastal & offshore mariculture in floating cages for temperature tolerant species of tuna, grouper, ornamental fish & other temperature tolerant species.

Soft natural barriers should be promoted as solutions for coastal inundation and strong wave action (i.e. establishment of artificial reefs, restoration of sand dune vegetation, etc.

Funds should be allocated for monitoring of ecosystem changes and for research programmes in above areas.

Photographs by P.B.T.P. Kumara

Ornamental fish inside sea weed

culture enclosures

Floating cages used for fish culture in China & other developed countries

Fish culture Fish culture Captive

breeding of reef fish

(Source: McHarg, I. L. 1995. Design with Nature)

Recommended Solutions

• Identify temperature tolerant species or more adaptable species, populations, varieties, etc.

• Develop temperature tolerant species through captivity breeding (through line breeding)

• Culture or fattening of fish in off shore floating cages

Thank you