Abundance and Run Timing of Adult Salmon in Gisasa River, Koyukuk National Wildlife Refuge, Alaska, 2004. Alaska Fisheries Data Series Number 2005-20

摘要

During 2004, a resistance board weir was used to record escapement information for Chinook Oncorhynchus tshawytscha and chum salmon O. keta in the Gisasa River, a tributary of the Koyukuk River, Alaska. An estimated total of 1,774 Chinook salmon migrated through the weir. Five age groups were identified from 540 Chinook salmon sampled, with age 1.2 (39 percent) dominating. The sex ratio was 31 percent female and 69 percent male. The mean length for 181 females was 835 mm, range 560-985 mm, and the mean length for 359 males was 648 mm, range 340-920 mm. An estimated total of 37,851 chum salmon migrated through the weir. Three age groups were identified from 724 chum salmon sampled, with age 0.3 (75 percent) dominating. The sex ratio was 44 percent female and 56 percent male. The mean length for 357 females was 553 mm, range 470-630 mm, and the mean length for 367 males was 588 mm, range 480-680 mm. The most abundant non-salmon species was longnose sucker Catostomus catostomus (N=29), followed by Arctic grayling Thymallus arcticus (N=23), whitefish (Coregoninae; N=21), and northern pike Esox lucius (N=11). Chinook and chum salmon escapement counts from this portion of the Koyukuk River drainage assist fisheries managers in making in-season decisions during the Yukon River commercial and subsistence fishing seasons, provide post-season evaluation of various management practices, and assist in developing future run projections.