Training of Trainers - Library - Network of Aquaculture Centres in ...

of the temperature rise that were dormant beforehand. Such changes will also mostly impact on temperateaquaculture.Nearly 65 percent of aquaculture production is inland, and over 80 percent barring seaweeds, and concentratedmostly in the tropical and sub-tropical regions in Asia. Climatic change impacts through global warming onpractices are likely to be small on such systems, and if at all positive brought about by enhanced growth rates ofcultured stocks. On the other hand, climate change will impact on water availability, changes in weather patterns,such as for extreme rain events, and exacerbate eutrophication and stratification in static (lentic) waters. Theinfluence of the former on aquaculture is difficult to project. However, based on the current practices, particularlywith regard to inland finfish aquaculture that is predominantly based on species feeding low in the food chain, thegreater availability of phyto- and zooplankton through eutrophication could possibly enhance production. On theother hand, adaptive measures are available for combating the potential negative impacts of the latter that couldarise through resulting oxygen depletion in the early hours. These in inland waters would include of setting up ofaquaculture practices in accordance with the carrying capacities of the water bodies, and continuous and regularmonitoring of water quality for nutrients and stratification levels, that would enable the movement of the cagefacilities for example to “safer” areas in the wake of major weather changes e.g. storms and potential upwelling.On the other hand, in marine cage culture the adaptive measures will revolve around introduction of bettertechnologies in respect of cage design that would withstand storms and wave surges.Sea level rise and consequent increased salt water intrusion in the deltaic areas of the tropics where there isconsiderable aquaculture production are likely to be impacted upon. Adaptations to these impacts will involvefurther inland movement of some of the existing culture practices of limited saline tolerant species (Stenohalinespecies) e.g. catfish (Pangasianodon hypophthalamus) in the Mekong Delta and utilization of the facilities alreadyin existence to culture more saline tolerant (euryhaline) species, e.g. Penaeid shrimps. Equally, aquaculture isseen as an adaptive measure to provide alternative livelihood means for terrestrial farming activities that may bemade no longer possible and or cost effective due to sea water intrusion and frequent coastal flooding.One of the most important impacts of climate change, but indirect, on aquaculture is considered to be broughtabout through limitations on fish meal and fish oil availability for feeds through a reduction in raw material supplies,for cultured carnivorous species; the negative impacts likely to be felt mostly on aquaculture in the temperateregions, where the mainstay of finfish aquaculture is based entirely on carnivorous species. The fish meal and fishoil availability will not only impact on aquaculture but on all forms of animal farming, albeit to different degrees.Adaptive measures to combat these impacts are suggested. However, overall for aquaculture to be sustainableand ecologically cost effective it is suggested that a major shift from culturing carnivorous finfish species tospecies feeding low in the trophic chain is considered more desirable.The ecological cost of aquaculture as opposed to producing other animal protein sources to meet the growinghuman food demands is presented. The general notion that aquaculture reflects salmonid and shrimp culture, twoenvironmentally and energy costly farming practices is contested in view of the fact the great bulk of aquaculturecommodities feed low in the food chain, and consequently the most popularly practiced aquaculture, particularly inthe developing world, which also happens to be the main producers, is shown to be a considerably less energyconsuming food production sector. Aquaculture is dependent on alien species to a relatively significant extent. Inthis regard, evidence is provided that fresh introduction of species should not only consider potential economicgains, which more often than not tend to be short term, but consider the energy cost of such introductions, hencedirect and/or indirect contribution to green house gas emissions, in comparison to the other available options. Thissuggestion is backed up with data on shrimp aquaculture, where the options of introducing alien species arecontroversial and remains unsolved in respect of policy development for some major shrimp producing nations inAsia.72