Salmon studies in interior Alaska, 1993

Description

In 1993, abundances were estimated for chinook salmon Oncorhynchus tshawytscha that returned to spawn in the Salcha River and Chena River near Fairbanks, Alaska. Estimates of abundance were also made for chum salmon Oncorhynchus keta at the same time; however, the time period that was sampled (1 July through 8 August) covered only a portion of the chum salmon population. Chinook and chum salmon were counted during 20 min periods each hour as they passed beneath the Richardson Highway bridge on the Salcha River and the Moose Creek Dam on the Chena River. Estimates of abundance for chinook and chum salmon in the Salcha River were 10,007 (SE = 360) and 5,809 (SE = 250), respectively. Estimates of abundance for chinook and chum salmon in the Chena River were 12,241 (SE = 387) and 5,400 (SE = 248), respectively. In early August, chinook salmon carcasses were collected from both rivers. Males comprised 72% of the carcass sample in the Salcha River and 83% in the Chena River. In both rivers, more than 80% of the males were age 1.3 or younger while 77% of the females were age 1.4 or older. Estimated potential egg production for the chinook salmon population in the Salcha River was 23 million eggs (SE = 2.1 million). Potential egg production was not estimated for the Chena River chinook salmon population because the sample was too small. The highest counts of chinook salmon during aerial surveys were 3,636 for the Salcha River and 2,943 for the Chena River populations. These aerial counts were about 36% and 24% of the respective abundance estimates. Chinook salmon were captured and tagged near Manley on the Tanana River to estimate the migration time to the Salcha and Chena rivers. Four-hundred- thirteen chinook salmon were captured and 403 were tagged and released from 12- 15 July. The tagged salmon were counted as they passed the counting sites on each river and as they were caught in the commercial and subsistence fisheries. Only two chinook salmon were sighted at the Salcha River (24-25 July), eight were sighted at the Chena River (20 July - 2 August), and 19 were captured in the commercial and subsistence fisheries (16-24 July). Mean migration times from Manley were 11.0 days (SE = 1.4) to the Salcha River and 11.6 days (SE = 3.5) to the Chena River counting sites. Coho salmon in the Delta Clearwater River near Delta Junction were counted from a drifting river boat on six occasions during September and October, 1993. Counts of coho salmon ranged from 228 on 23 September (only a portion of the river was surveyed) to 10,875 on 21 October (the entire river was surveyed). Two-hundred- ninety-nine carcasses were collected on 8 November. The sex composition of the sample was 52% male and 48% female. Ages 1.1 and 2.1 comprised 63% and 37% of the sample, respectively.

Subjects

Genres

• Statistics

Series Statement

• Fishery data series -- no. 94-14.

Links

• URL