Catch-to-Escapement Ratios of Fin-Marked 1950-Brood Puget Sound Coho Salmon

Abstract

Five groups of fin-marked coho salmon (Oncorhynchus kisutch) were released as fingerlings in 1952 into two Puget Sound (Washington) drainages. Three groups were released into Minter Creek (southern Puget Sound) and two into Lake Washington drainage (middle Puget Sound). About 90% of the salmon released into the Lake Washington drainage migrated to the Pacific Ocean, whereas, only 45% of those planted into Minter Creek migrated to the Pacific Ocean. Catch-to-escapement ratios for salmon from the five groups which remained as feeding fish within Puget Sound varied from about 2 to 5:1. For salmon released at Minter Creek, the catch-to-escapement ratio was 4:1 and for those released into the Lake Washington drainage, it was 3:1. In contrast, catch-to-escapement ratio for those salmon migrating to the Pacific Ocean was roughly ten time greater for fish released into Lake Washington watershed (14.1:1) than for fish released at Minter Creek (1.4:1). This large difference was due in part to their time and place of migration in salt water as related to ocean fisheries. Groups of salmon, however, returning to the same area of release, had similar catch-to-escapement ratios (Minter Creek—1.3, 1.5, 1.5; Lake Washington—14.6, 13.6). The catch-to-escapement ratio for all five groups of 1950-brood fin-marked coho salmon was 3.2:1. Salmon remaining within Puget Sound for feeding tended to have a similar chance of capture because of an intensive sport fishery, whereas, salmon migrating to the Pacific Ocean showed wide variation in chance of capture as correlated with time and place of migration to points of release.