Aquaculture is considered as a sunrise sector for increasing fish production since the capture fisheries

have reached almost stagnation levels. With more than 8% annual growth globally, the sector is now

considered as the fastest growing food producing sector in the world. Today aquaculture provides around

half of the fish for human consumption and this share will need to grow further. The global aquaculture

production showed that 25.8 million tonnes (m t) of freshwater organisms were produced (43.8%), 30.2 m

t (50.9%) of marine organisms, and 3.4 m t of brackishwater organisms comprising nearly 63% shrimps

(FAO, 2006)

Gopakumar, G

CMFRI Digital Repository

CMFRIWinter School onImpact of Climate Changeon Indian Marine FisheriesLecture NotesPart 1Compiled and Edited byE. Vivekanandan and J. JayasankarCentral Marine Fisheries Research Institute (CMFRI),(Indian Council of Agricultural Research)P.B. No. 1603, Cochin - 682 018, Kerala(18.01.2008 - 07.02.2008)CMFRI - Winter School on Impact of Climate Change on Indian Marine Fisheries 90Challenges posed by climate change in the future scenario of coastal aquacultureCHALLENGES POSED BY CLIMATE CHANGE IN THEFUTURE SCENARIO OF COASTAL AQUACULTUREG. GopakumarMandapam Regional Centre of CMFRI, Mandapam CampIntroductionAquaculture is considered as a sunrise sector for increasing fish production since the capture fisherieshave reached almost stagnation levels. With more than 8% annual growth globally, the sector is nowconsidered as the fastest growing food producing sector in the world.  Today aquaculture provides aroundhalf of the fish for human consumption and this share will need to grow further.  The global aquacultureproduction showed that 25.8 million tonnes (m t) of freshwater organisms were produced (43.8%), 30.2 mt (50.9%) of marine organisms, and 3.4 m t of brackishwater organisms comprising nearly 63% shrimps(FAO, 2006).Mariculture is the farming and husbandry of marine plants and animals in marine environments.Although we have vast cultivable coastal areas, the annual production is only about 80,000 to 1,00,000tonnes, and that too is from brackishwater shrimp aquaculture.  A trade of marine ornamental fishes andother tropical marines is emerging in recent years. The techno-economic and commercial viability ofmariculture in Indian conditions is yet to be demonstrated and practiced except for shrimp and a few bivalves.The potentially cultivable candidate species in India include about 20 species of finfishes, 29 crustaceans,17 molluscs, 7 seaweeds and many other species of ornamental and therapeutic values.  Many mariculturetechnologies are very simple, eco-friendly and use locally available infrastructure facilities for constructionof farm, feed and seed, and hence the fishermen can practice the entire farming.  Another advantage is thatmost of our brackishwater and coastal areas are free from pollution and suited for aquaculture.  But hardly10% of the potential cultivable area is presently used for aquaculture in spite of growing demand for culturedshrimp, bivalves, crabs, and lobsters etc., all of which are in high demand in the export market.Threat of Climate ChangeIt is now widely accepted that fisheries and aquaculture are threatened by climate changes, andhence, it is necessary to understand the nature of threat for developing strategies for coping up with thesame.  Temperature is predicted to increase more at higher latitudes compared with equatorial areas.  As aglobal average, precipitation levels are predicted to increase. Changes in seasonal variation will also beimportant and may lengthen or shorten growing seasons of farmed organisms in relation to water availabilityor increase the risk of flood damage at certain times of the year. Mean sea level is predicted to increasebetween 10 and 90 cm during the 21st century with most predictions falling within the 30 to 50 cm rangealthough some uncertainty remains in relation to land-based ice in Antarctica and Greenland. Changes inclimate variability and extreme events are considered harder to predict although increases in the intensity ofprecipitation events, risk of drought and peak cyclone wind intensities are considered likely in some areas.Changes in ocean currents may have a substantial influence on the world’s climate which will in turn havesignificant direct effects on mariculture through changes in temperature, primary productivity and hencefood availability, and the distribution of disease, toxic algae blooms and predators (WorldFish Center,2006).Impacts of Climate Change(i) Sea surface temperature changes:  The following impacts can be anticipated on culture systems Increase in harmful algal blooms that release toxins in the water and produce mass mortalityof fishCMFRI - Winter School on Impact of Climate Change on Indian Marine Fisheries 91Challenges posed by climate change in the future scenario of coastal aquaculture Decrease in dissolved oxygen Increased incidence of disease and parasites Enhanced growing seasons Change in the location and/or size of the suitable range for a given species Lower natural winter mortality Enhanced growth rates and feed conversions Enhanced primary productivity to benefit production of filter feeders Altered local ecosystems – competitors and predators Competition, parasitism and predation from exotic and invasive species Damage to coral reefs that may have helped to protect shore from wave action – may combinewith sea level rise to further increase exposureThe following operational impacts are expected: Changes in infrastructure and operational costs Increased infestation of fouling organisms, pests, nuisance species and/or predators Expanded geographic distribution and range of aquatic species for culture Changes in production levels Increased chance of damage to infrastructure from waves or flooding of inland coastal areasdue to storm surges(ii) Change in other oceanographic variables  (variations in wind velocity, currents and wave action)The following impacts are anticipated: Decreased flushing rate that can affect food availability to shellfish Alternations in water exchanges and waste dispersal Change in abundance and/or range of capture fishery species used in the production of fishmeal and fish oilThe major expected operational impacts are: Accumulation of waste under pens Increased operational costs(iii) Sea level rise:  The impacts anticipated on culture systems include More areas may be available for coastal aquaculture Loss of areas such as mangroves that may provide protection from waves/surges and act asnursery areas that supply aquaculture seed Sea level rise combined with storm surges may create more severe flooding Salt intrusion into ground waterThe expected operational impacts include Damages to infrastructure Changes in aquaculture zoningCMFRI - Winter School on Impact of Climate Change on Indian Marine Fisheries 92Challenges posed by climate change in the future scenario of coastal aquaculture Competitions for space in ecosystems like mangroves Reduced freshwater availability(iv) Increase in frequency and/or intensity of storms: The anticipated impacts on the culture systems include Larger waves Storm surges Flooding from intense precipitation Structural damage Salinity changes Introduction of disease or predators during flood episodesThe expected operational impacts include Loss of stock Damage to facilities Higher capital costs, need to design cages moorings, jetties etc that can withstand events Negative effect on pond walls and defenses(iv) Floods due to changes in precipitation: The anticipated impacts on culture systems include Salinity changes Introduction of disease or predators Structural damage Escape of stockThe expected operational impacts include Loss of stock Damage to facilities Higher capital costs involved in engineering flood resistance(v) Drought (as an extreme event): The anticipated impacts on culture systems include Salinity changes Reduced water quality Limited water volumeThe expected operational impacts include Loss of stock Loss of opportunity – limited productionStrategies for adapting to the challenges of climate change in coastal aquaculture/maricultureIt is evident that climate change will increase the potential of aquaculture in some regions and reducein others. Aquaculture is an important means of diversifying and improving the productivity of farmingsystems and for improving food security in many regions especially in Africa and Asia. Implemented properly,it can help conserve water and its potential to help farmers adapt to climate change is enormous.  Thefollowing strategies appear to be relevant: Because of their short generation time and large multiplication rate, fish can be quickly and efficientlyselectively bred to suit to the new conditions that are likely to be brought about by climate change. Research on diversification of species and farming practices to suit the impact of climate change isneeded.CMFRI - Winter School on Impact of Climate Change on Indian Marine Fisheries 93Challenges posed by climate change in the future scenario of coastal aquaculture Breeding and seed production of fast growing and hardy species of tropical finfish and shellfishhave to be taken up. Natural fish seed availability from mangroves may be reduced due to loss of mangrove habitats andhence alternate sources for seed for aquaculture have to be resorted. Since loss of coastal areas and flooding is anticipated, coastal aquaculture areas have to be selectedby taking these aspects into consideration. Coastal agricultural lands, which will become unsuitable for crop production because of increasedseawater intrusion, can be deployed for coastal aquaculture. Offshore mariculture practices such as cage farming have to be designed for withstanding theexpected increased intensity/ frequency of storms.ReferencesFAO 2006. State of world aquaculture 2006. FAO, Rome, Italy. 134pp.World Fish Centre 2006. The Threat to Fisheries and Aquaculture from Climate Change. Policy Brief,www.worldfishcenter.org.

Challenges posed by climate change in the future scenario of coastal aquaculture

 -Winter School on

Impact of Climate Change on Indian Marine Fisheries held at CMFRI, Cochin 18.1.2008 to 7.2.2008

http://eprints.cmfri.org.in/5316/1/17.pdf

Challenges posed by climate change in the future scenario of coastal aquaculture -Winter School on Impact of Climate Change on Indian Marine Fisheries held at CMFRI, Cochin 18.1.2008 to 7.2.2008

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