Induction of precocious sexual maturity in male pink salmon ( Oncorhynchus gorbuscha )

• Published in: Canadian Journal of Zoology
• Main Authors: Funk, James D., Donaldson, Edward M.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1972
• Subjects: Animal Science and Zoology; Ecology, Evolution, Behavior and Systematics; Oncorhynchus gorbuscha; Pink salmon
• Online Access: http://dx.doi.org/10.1139/z72-190; http://www.nrcresearchpress.com/doi/pdf/10.1139/z72-190

In the juvenile male pink salmon (Oncorhynchus gorbuscha) complete sexual maturity was attained by September in the year of hatching with thrice-weekly treatments of 10.0 and 1.0 μg partially purified salmon (Oncorhynchus tshawytscha) gonadotropin (SG-G100) per gram body weight. The time of onset of mitotic division of spermatogonia and the rate of spermiogenesis were accelerated in the precociously mature testes. At sexual maturity, a scattering of localizations of Δ5-3 β hydroxysteroid dehydrogenase activity was observed in the testes which corresponded to the distribution of the interstitial cells. A stock of larger pink salmon (body weight at maturity 64.2 g) developed mature testes in the same time interval as the smaller sized individuals, but in these the gonads were four times larger. Immature Oncorhynchus tshawytscha matured more slowly and showed less 3 β-ol dehydrogenase activity in response to SG-G100 than the pink salmon.