PUBERTY CONTROL IN FARMING OF SALMON, COD AND HALIBUT

摘要

Early male puberty is a significant economic problem in farming offish species in Europe such as Atlantic salmon, rainbow trout, sea bass, sea bream, turbot, halibut and Atlantic cod. Onset of puberty and sexual maturation leads to loss of growth, lower harvest quality and often increased risk for disease outbreaks and mortality. In species that survive sexual maturation, the loss of body mass during spawning is often regained by compensatory growth after the spawning season - but at the cost of a low feed conversion efficiency that both affects the profitability and the sustainability of the farming industry. Moreover, salmonids lose much of their ability to regulate ion- and water balance in seawater when sexual maturation approaches, and high mortalities can be expected if they are kept in seawater throughout the spawning season. Finally, compared to immature fish, sexual mature farmed fish may represent a larger risk for genetic impact on local wild stock, either after escape or after release of fertilised eggs into the natural environment. It is therefore necessary to develop strategies to arrest or delay puberty so the fish can reach harvestable size before sexual maturation occurs. However, significant gaps exist in our knowledge as regardsthe physiological regulation of puberty (Okuzawa 2002) limiting our ability to develop strategies to combat the problem.