Abstract
Early puberty is a main problem in fish farming in a range of species like Atlantic salmon, rainbow trout, sea bass, sea bream and Atlantic cod. Completion of puberty normally results in loss of growth and flesh quality, and can have negative effects of fish welfare and health in aquaculture, and ultimately affect sustainability. Age and size at puberty are also key life history traits in wild populations due to their importance for fitness. Most species show large phenotypic and genetic plasticity in these traits, which in turn affects the productivity of wild stocks and sustainability of farmed fish. Fisheries have also been shown to affect age and size of puberty in wild stocks, and these changes have been suggested to be partly due to genetic effects. There seems to be a strong link between rapid growth and early puberty in many species, as predicted by life history theory, whereas changing growth rates can have more variable effects at size at puberty. We have studied age and size at puberty in farmed salmon and cod populations, and documented such links between growth and puberty. However, photoperiod control has proven more effective in controlling age at puberty in farmed salmon and cod. We have also used photoperiod treatments to study the underlying mechanisms of puberty control in salmon and cod, and also in the context of variable growth and adiposity of the fish, as well as the genetic variation in the response. We have characterized a range of the genes that are involved in puberty control in salmon and cod. The talk will address these issues, including results on some of the key components in the brain-pituitary-gonad axis controlling sexual maturation - and the impact of environmental factors such a photoperiod and feed availability on the activation of this axis.
Dr. Geir Lasse Taranger
Institute of Marine Research
Head of Research Group Reproduction and Growth
PO Box 1870 Nordnes
5817 Bergen, NORWAY