By Jan Henning L'Abee-Lund
Aquaculture, Volume 121, Issues 1-3, Salmonid Smoltification IV, 15 March 1994, Pages 65-71, ISSN 0044-8486, DOI: 10.1016/0044-8486(94)90008-6.

Anadromous brown trout (Salmo trutta) were sampled at spawning in six Norwegian rivers, located between 58 and 64 degrees N. Sea age at first maturity was significantly influenced by the growth rate at sea, but not by the growth rate in the river. Between rivers, sea age at maturity declined with increasing smolt age. Within rivers, browth trout from upper stretches smoltified at an older age and matured at an older sea age than brown trout from the lower stretches. Males matured at a younger sea age than females. Smolt age, sex and environmental conditions accounted for about 30% of the overall variation in sea age at first maturity.

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