Surveys and stock monitoring of rainbow and steelhead trout in the upper Copper River drainage during 1998

Description

Rainbow and steelhead trout studies were initiated in 1998 in the Upper Copper Upper Susitna Management Area which is located in South Central Interior Alaska. Surveys and sampling were conducted at three locations in the Copper River drainage: the Gulkana, Tazlina and Hanagita drainages. These studies collected information on rainbow and steelhead trout in terms of presence, spawning concentrations and, age and size information. Riverine habitat was described in general terms so that information is available for planning future stock assessment studies. During spring sampling we found seven resident rainbow and two steelhead trout in one spawning area in the middle fork Gulkana near Dickey Lake, and approximately 150 previously constructed redds. Along Hungry Hollow Creek, 17 resident rainbow and seven steelhead trout were tagged and sampled. In a sampling trip during the summer feeding period, 55 trout were caught. The size composition of these fish suggested that catch-and-release regulations have been effective at increasing average length of rainbow trout in the Gulkana River, even though there have been increasing numbers of anglers each year. At Kaina Creek in the Tazlina River drainage, a 21 mi survey was conducted, and spawning rainbow and steelhead were observed. Few fish were sampled but recently constructed redds were present which suggested trout may have spawned prior to our survey. In the Hanagita River drainage, immigrating steelhead trout were sampled in an attempted mark-recapture experiment. Sampling and tagging were conducted on fall-run steelhead. Only 10 steelhead were sampled. An estimate of abundance could not be generated. In the course of the study we observed pre-spawning adult steelhead farther up the Hanagita River drainage than previously recorded. The observed geographic distribution of Hanagita steelhead was different from observations in previous years in that fish were not concentrated near inlets to, and the outlet from, Hanagita Lake. It is likely that these changes in geographic distribution of steelhead within the drainage created concerns over the population status and led to a decline in the sport fishery, which historically targeted fish holding near inlets and the outlet of Hanagita Lake.

Subjects

Series Statement

• Fishery data series -- no. 99-37.

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