Environmental impacts of genetic improvement in growth rate and feed conversion in fish farming under density and nitrogen limitation

Many environmental impacts can be attributed to fish farming and there is a need to explore new ways of reducing environmental impacts, such as fish genetic improvement. The environmental consequences of genetic improvement in thermal growth coefficient (TGC) and in feed conversion ratio (FCR) were investigated, therefore, in an African catfish farm in Recirculating Aquaculture System. A Life Cycle Assessment study was conducted and combined with a bioeconomic model of genetic response. Results show that environmental consequences of genetic improvement in TGC and FCR are different among impact categories, depending on their main contributors and on the factor limiting production at farm level. Genetic improvement of FCR always leads to lower environmental impacts while improving TGC decreases environmental impacts only when density was the limiting factor. Those results are important for the future development of selective breeding programs in fish farming taking into account environmental impacts