Abundance and distribution of the chinook salmon escapement on the Chickamin River, 1996

Description

The distribution and abundance of large chinook salmon Oncorhynchus tshawytscha that returned to spawn in the Chickamin River in 1996 was estimated by using radio telemetry and a mark-recapture experiment. Age, sex, and length compositions were estimated for the immigration. Set gillnets were used to capture 183 immigrant chinook salmon 660 mm in (mid-eye to fork) length during June, July, and August 1996; 174 fish were marked with spaghetti tags and opercle punches, and 112 of these also had radio transmitters inserted into their stomachs. One hundred and one (101) of the radio-tagged fish were tracked to spawning locations; 84 in survey index areas and 17 in unsurveyed streams. During August, 380 chinook salmon 660 mm long were captured at spawning sites and inspected for tags; 41 of these fish had been previously marked. A modified Petersen model (n1 = 174, n2 = 380, m2 = 41) estimated that 1,587 (SE = 199) chinook salmon 660 mm in length immigrated to the Chickamin River in 1996. Peak survey counts in August totaled 422 large chinook, about 27% of the estimated inriver run. From immigrant age and length composition data collected in gillnet and spawning ground samples, it was estimated that 5.7% of the gillnet catch was age-1.1, 14.0% was age-1.2, 47.7% age-1.3, 25.4% age-1.4, and 3.1% age-1.5 (96 males and 97 females) and that 2.4% of the spawning ground samples were age-1.1, 7.7% age-1.2, 56.5% age-1.3, 30.4% age-1.4, and 2.7% age-1.5 (180 males and 195 females).

Subjects

Series Statement

• Fishery data series -- no.97-28.

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