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- Title
Marine survival difference between wild and hatchery-reared steelhead trout determined during early downstream migration.
- Authors
Melnychuk, Michael C.; Korman, Josh; Hausch, Stephen; Welch, David W.; McCubbing, Don J.F.; Walters, Carl J.; Grant, James
- Abstract
We observed large survival differences between wild and hatchery-reared steelhead trout ( Oncorhynchus mykiss) during the juvenile downstream migration immediately after release, which persisted through adult life. Following a railway spill of sodium hydroxide into the Cheakamus River, British Columbia, a short-term conservation hatchery rearing program was implemented for steelhead. We used acoustic telemetry and mark-recapture models to estimate survival of wild and (or) hatchery-reared steelhead during 4 years of the smolt migration, with both groups released in 2008. After adjusting for estimated freshwater residualization, 7%-13% of wild smolts and 30%-40% of hatchery smolts died in the first 3 km of the migration. Estimated survival from release to ocean entry was 71%-84% for wild fish and 26%-40% for hatchery fish and to exit from the Strait of Georgia system was 22%-33% for wild fish and 3.5%-6.7% for hatchery fish. A calculated 2.3-fold survival difference established during the downstream migration was similar to that after the return of adult spawners, as return rates were 8.0% for wild fish and 4.1% for hatchery fish. Contrary to current understanding, a large proportion of salmon mortality in the smolt-to-adult period, commonly termed 'marine mortality', may actually occur prior to ocean entry.
- Subjects
BRITISH Columbia; AQUATIC biology; STEELHEAD trout; HATCHERY fishes; ANIMAL migration; SEASONAL effects on wildlife; RIVERS; ANIMAL behavior; RIVER ecology
- Publication
Canadian Journal of Fisheries & Aquatic Sciences, 2014, Vol 71, Issue 6, p831
- ISSN
0706-652X
- Publication type
Article
- DOI
10.1139/cjfas-2013-0165