Abundance and distribution of the chinook salmon escapement on the Stikine River, 1997

Description

The distribution and abundance of large (660mm MEF) chinook salmon Oncorhynchus tshawytscha that returned to spawn in the Stikine River above the U.S./Canada border in 1997 were estimated by means of radio telemetry and a mark-recapture experiment. Age, sex, and length compositions for the immigration were also estimated. Drift gillnets fished near the mouth of the Stikine River were used to capture 731 immigrant chinook salmon during May, June, and July, 1997; 702 of these fish were marked with spaghetti tags, opercle punches and axillary appendage clips, and 255 also had radio transmitters inserted into their stomachs. During July and August, chinook salmon were captured at spawning sites and inspected for tags. Marked fish were also recovered from Canadian commercial, test and aboriginal fisheries. Using a modified Petersen model (M = 653, C = 4,528, R = 93) we estimated that 31,509 (SE = 2,960) large chinook salmon immigrated to the Stikine River above Kakwan Pt. Canadian fisheries on the Stikine River harvested 4,513 large chinook salmon, which left an escapement of 26,996 large fish. The total count at the Little Tahltan River weir was 5,557 large chinook salmon, about 20% of the estimated spawning escapement. We used weir counts and a foot survey to estimate an escapement of 478 large fish in Andrew Creek. From the radio telemetry study, we estimated that 17.7% of the spawning chinook salmon went to the Little Tahltan River, 17.5% to the Iskut, 4.7% to the Chutine, 3.5% to the Christina, 25.8% to the Tahltan, 21.8% to upper Stikine, 7.2% to lower Stikine and 1.8% to U.S. tributaries. An estimated 2% of the Kakwan Point gillnet catch was age -1.2, 26% age -1.3, 70% age -1.4, and 1% age -1.5; 232 males and 352 females were captured. An estimated 3% of spawning ground samples were age -1.2, 24% age -1.3, 72% age -1.4, and 0.4% age -1.5; 323 males and 438 females were sampled.

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