The effect of external abrasion of smolts on the return rate of maiden adult steelhead (Oncorhynchus mykiss) was assessed in a preliminary experiment at the Keogh River in south coastal British Columbia. Abrasion was defined by the incidence of scale loss, fin abrasion and opercular abrasion. Smolts with "low abrasion" (7300) and "moderate abrasion" (10,300) were marked and released at similar sizes in the lower Keogh River during early May 1984. Based on population estimates of returning adults in 1986 and 1987, the survivals of the low and moderate abrasion groups were not significantly different: 8.7% and 7.2%, respectively. Both groups returned at similar mean lengths after 2- and 3-ocean years. In addition, recoveries of adults as upstream migrants and downstream kelts combined were examined for differences between the two abrasion groups. Recovery rates from the low and moderate abrasion groups were similar: 4.0 and 4.3%, respectively. Corresponding recoveries of age 2-ocean steelhead were 2.1 and 2.3%,
Slaney, Pat A., Ward, Bruce R.; Berg, Linda. 1990. A Preliminary Assessment of the Effect of External Abrasion on the Smolt-to-Adult Survival of Net-pen Cultured Steelhead Trout. Ministry of Environment. Fisheries Technical Circular. FTC88
Topic: Fish and Fish Habitats
Keywords: steelhead, Oncorhynchus mykiss, Keogh River, survival, returns, abrasion
Scientific Name: Oncorhynchus mykiss
English Name: Rainbow Trout
Other Identifier: Department of Fisheries and Oceans
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