Climate change and aquaculture
Experimental shrimp ponds
Courtesy of NOAA/Sea Grant Program/J.P. McVey
Aquaculture has been contributing strongly to the growth in fisheries production, contributing to nearly half the fish consumed as food. Aquaculture not only contributes jobs and food but also helps the whole fisheries sector by smoothing out the peaks and valleys of natural production. This keeps prices steadier and enables restaurants and markets to keep their products stable. Production usually concentrates on species with higher prices, such as shrimp, salmon and trout and on species that are easier to produce, such as catfish.
Increased technology is being developed to control disease, move operations onshore to avoid the competition for shoreline space, and to recycle effluents. Much work is also underway in genetics to control disease, and produce faster growing or otherwise more desirable animals. On the other hand, resource managers and fishers are very concerned about the possibilities of escape of engineered fish into the ocean, where they may lead to problems with the wild stocks. Of particular concern is that the new fish will have inadequate genetic diversity to deal with changing environments and possible new pathogens. This is a well-founded concern. Escapees in some areas have exceeded the production of wild stocks.
Ocean ranching, in which fish are released to fend for themselves in the ocean and then return to a particular area for harvest, leads to some of the same concerns as aquaculture. In addition, there is the concern that some areas of the ocean are already at their carrying capacity and are unable to support increased predatory fish.
The projected climate change will generally be positive for aquaculture, which is often limited by cold weather. Since many of the changes will involve warmer nights and winters, there should be longer periods of growth, and growth should be enhanced. Also, there should be lower costs from the need to make structures ice-resistant and to heat water to optimum temperatures.
Problems expected from a warming environment include a greater susceptibility of disease organisms to thrive. This is particularly true if engineered fish lack the innate abilities to deal with new strains of pathogens, or if the facility relies too heavily on chemicals to control disease. Also, in some areas, some species may already be near their upper temperature tolerances. Such facilities will be at a disadvantage if alternative species or technologies cannot be developed.