Trapping, rearing and coded-wire nose tagging of Atnarko River chinook fry, 1974-1978 / by Russ T. Hilland.: Fs97-4/1509E-PDF

"Between April 3 and May 23, 1974, 20,320 chinook salmon fry were trapped from the Atnarko River and reared to nose-tagging size. On August 17, 8,648 were marked with a left pelvic clip and released. This study tested the feasibility of trapping, rearing and marking sufficient numbers of fry from a wild stock for assessment of ocean migration patterns and fishery contributions. As the results of the feasibility study indicated that more fry could be captured and rearing time reduced, the program was repeated in 1975, 1976, 1977, and 1978. In 1975, 64,141 fry were trapped. Interruption of the water supply to the rearing tubs forced premature termination of the program. In 1976, due to unfavourable water conditions, only 7,895 fry were obtained for rearing. These fry grew to tagging size by June 29 - 6,878 were subsequently nose-tagged and released. In 1977, 54,978 fry were nose-tagged and released by June 24. In 1978, hatchery and wild fry were reared separately at the Atnarko facility. The two groups were tagged with differently coded wire nose-tags (14,806 hatchery fish received codes 20/20 and 21/21; 57,654 wild fish received code 20/22). A comparison of growth and survival rates suggests that hatchery fry grow to tagging size more rapidly than wild fry, with fewer mortalities. As tag recovery information becomes available, smolt-to-adult survival rates for the two groups will be compared and final conclusions drawn regarding "wild" vs. "hatchery" chinook production"--Abstract, page iii.

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