Losee, James
- Department of Wildlife, Fish and Environmental Studies, Swedish University of Agricultural Sciences
- Wild Salmon Center
Abstract
Anadromy allows fishes to spawn in freshwater habitats and then feed at sea, where they tend to grow faster than would have been the case had they remained in freshwater. However, mortality rates often differ between these habitats, and the tradeoff between benefits and risks can result in partial anadromy - the existence of migratory and non-migratory components in populations. In salmonids, the anadromous life history can be more prevalent among females than males because the sexes differ in the relationship between size and reproductive success. However, anadromy exposes salmonids to different sources of natural and fishery-related mortality, so it is important to assess such partial anadromy. Here we present three independent datasets, two based on visual assignment of sex and one based on genetic methods, indicating that the sex ratio in coastal cutthroat trout, Oncorhynchus clarkii clarkii, sampled in brackish and marine waters of Washington, USA and southern British Columbia, Canada were female-biased (N = 605, 64% females), unlike those sampled in streams (N = 70, 44.3% females). Given the importance of females for the productivity of populations, these findings emphasize the importance of regulations minimizing fishing mortality of cutthroat trout in marine waters and the protection and improvements of freshwater habitats to facilitate migration.
Keywords
Anadromy; Partial migration; Salmonid
Published in
Environmental Biology of Fishes
2026, volume: 109, number: 2, article number: 69
Publisher: SPRINGER
SLU Authors
UKÄ Subject classification
Fish and Aquacultural Science
Publication identifier
- DOI: https://doi.org/10.1007/s10641-026-01833-9
Permanent link to this page (URI)
https://res.slu.se/id/publ/146760