Migration patterns of anadromous Cutthroat Trout in South Puget Sound: A fisheries management perspective

Abstract

In Washington State, anadromous Cutthroat Trout are targeted by sport fishermen in the marine environment, year round in catch and release fisheries, however little is known regarding marine stock distribution and migration patterns. The current study was designed to (1) describe the size, age and stock structure of Cutthroat Trout captured in marine waters of South Puget Sound, (2) estimate travel distances of individual Cutthroat Trout and (3) evaluate factors that determine travel distances. Genetic assignment of fish captured in inlets to their population of origin was performed, and marine migration patterns were inferred from the genetic assignments. Cutthroat Trout in South Puget Sound were frequently recovered outside of their natal inlet. Fish originating from Skookum Creek were disproportionately represented in the study area representing 78.8% of the total catch and were found in every marine sampling area while 90% of McLane and 100% of Kennedy Creek fish were found in their natal inlet. Travel distances were greatest during summer months (Mean: 18.9km±4.9S.D.) and shortest during fall (Mean: 6.0km±7.9S.D.), prior to spawning. Complex migration patterns of Coastal Cutthroat Trout resulted in a mixed stock fishery for most of the year and have the potential to make protection of smaller populations difficult in the marine environment. Catch and release regulations in marine waters have likely had a positive effect on the total abundance of anadromous Cutthroat Trout in Washington State however, managers should focus population specific recovery efforts in the freshwater and estuarine environments where Cutthroat Trout populations segregate naturally as they return to natal waters.