Cod puberty - age at first maturation in relation to season, growth end energy acquisition during the first year of life

Interest in cod farming has increased tremendously during the past year, with large economic investments particularly in juvenile production. A major bottleneck is early sexual maturation, which commonly occurs at two years of age in captively reared cod. This is before the fish has reached market size and is accompanied by weight loss due to spawning. To ensure a viable industry, which ultimately depends on how fast and at which cost a marketable size can be reached, onset of puberty must therefore be de layed by at least one year. Recent experiments indicated that growth rate or body size during the first year after hatch may affect the age of puberty. Consequently, the aim in this proposal is to analyze the seasonal effects of different growth on age at puberty. We will control gr owth by varying the feed ration. Endocrine and histological tools will be used to pinpoint the timing of reproductive events as well as to increase the general understanding of cod reproductive physiology. A better understanding of how events during the f irst year of life affect later growth and maturation will ultimately lead to the development of more reliable and efficient methods to block or delay maturation with maintained or improved somatic growth