Southeast Alaska steelhead studies, 1997

Alternate Titles

• Situk River weir and surveys of index streams.

Description

Regionwide monitoring of trends in steelhead Oncorhynchus mykiss spawning abundance was standardized by implementing snorkel gear for survey use in fourteen index streams in Southeast Alaska during 1997. Each of these fourteen index streams was surveyed for steelhead abundance by a two- or three-person team using snorkel gear during April and May 1997. In addition, two other streams were surveyed and evaluated for their potential as index streams of steelhead abundance. Steelhead peak counts in the only two systems which had been previously surveyed using snorkel gear were down slightly in 1997. The Situk River produces the largest run of steelhead in Southeast Alaska. Between 7 May and 8 August, 7,328 steelhead were counted as they emigrated downstream through a weir located 1.2 miles upstream of the Lower Landing on the Situk River. In float surveys conducted on 4 May (upper river) and 5 May (lower river) on the Situk River, 4,943 steelhead were counted, constituting 67% of the number counted at the weir. We sampled a total of 797 steelhead from the Situk River for scales, sex, and total length. The average total length of female steelhead was 787 mm (SE = 3). The average total length of male steelhead was 797 mm (SE = 5). Of the fish sampled, 48 or 6.0% (SE = 0.8%) were =36 inches snout-to-tip-of-tail; nine of these were female and 39 were male. On three nights during the seasonal emigration, a comparison of length, sex, coloration, and presence of external fungus on fish was made between an early evening sample and a late evening sample. Few differences were observed in sex and length composition between samples taken early in the evening versus late in the evening.

Subjects

Series Statement

• Fishery data series -- no. 98-45.

Links

• URL