Marking, enumeration, and size estimation of coho and chinook salmon smolt releases into upper Cook Inlet, Alaska in 1995

Description

Southcentral Alaska contains the majority of the state's human population and receives the vast majority of the state's fishing pressure, both of which are increasing. To meet the growing demand on the sport fishery resource, hatchery-reared chinook salmon and coho salmon smolt have been stocked in numerous locations throughout Southcentral Alaska to improve or create terminal sport fisheries. Over 495,000 coho Oncorhynchus kisutch and chinook salmon Oncorhynchus tshawytscha smolt released at 11 locations in Cook Inlet were marked with an adipose finclip and a coded wire tag. Tag retention ranged from 93.9% to 99.6%. About 70% of the coho salmon smolt produced at Ft. Richardson Hatchery for release into Ship Creek, Campbell Creek, and Nancy Lake were within the desired size range of 15.1 g to 25.0 g. Only 49.9% of the Bird Creek release group were in that size range and 48.4% were larger than 25 g. Late-run Homer Spit chinook salmon smolt produced at Elmendorf Hatchery achieved the production goal, with 90% of the smolt within the desired size range of 5.1 g to 15.0 g. None of the remaining chinook salmon release groups at Elmendorf Hatchery, nor the chinook salmon release groups at Ft. Richardson Hatchery, achieved the production goal. Three smolt enumeration techniques were compared. In most instances the mark-recapture estimate was the lowest of the three techniques at both hatcheries. The water volume estimate was the highest estimate in most instances at one hatchery, and the hatchery inventory estimate was the highest estimate in most instances at the other hatchery. The difference between mark-recapture and water volume estimates were not consistent for all groups. The difference between the mark-recapture estimate and the hatchery inventory estimate was consistent for most groups at each hatchery.

Subjects

Series Statement

• Fishery data series -- no. 96-15.

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