Puberty comprises the transition from an immature juvenile to a mature adult state
of the reproductive system, i.e. the individual becomes capable of reproducing sexually
for the first time, which implies functional competence of the brain-pituitary-gonad
(BPG) axis. Early puberty is a major problem in many farmed fish species due to negative
effects on growth performance, flesh composition, external appearance, behaviour,
health, welfare and survival, as well as possible genetic impact on wild populations.
Late puberty can also be a problem for broodstock management in some species, while
some species completely fail to enter puberty under farming conditions. Age and size
at puberty varies between and within species and strains, and are modulated by genetic
and environmental factors. Puberty onset is controlled by activation of the BPG axis,
and a range of internal and external factors are hypothesised to stimulate and/or
modulate this activation such as growth, adiposity, feed intake, photoperiod, temperature
and social factors. For example, there is a positive correlation between rapid growth
and early puberty in fish. Age at puberty can be controlled by selective breeding
or control of photoperiod, feeding or temperature. Monosex stocks can exploit sex
dimorphic growth patterns and sterility can be achieved by triploidisation. However,
all these techniques have limitations under commercial farming conditions. Further
knowledge is needed on both basic and applied aspects of puberty control to refine
existing methods and to develop new methods that are efficient in terms of production
and acceptable in terms of fish welfare and sustainability.
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