Stock Assessment of Arctic Grayling in Hungry Hollow Creek and Middle Fork Gulkana River, 2019 PDF Download

Author: Corey J. Schwanke
Publisher:
ISBN:
Category : Arctic grayling
Languages : en
Pages : 35

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Book Description
A 2-event mark–recapture study was conducted to estimate the abundance of Arctic grayling in a 9-river kilometer (RKM) reach of Lower Hungry Hollow Creek and Middle Fork Gulkana River in 2019. Intensive hook and line sampling occurred 18–22 July for the first event and 26–29 July for the second event. A total of 2,469 Arctic grayling ≥270 mm fork length (FL) were captured and marked during the first event and 2,270 were captured and examined during the second event, 204 of which were marked during the first event. A length-stratified Bailey estimator was used to estimate the abundance of Arctic grayling ≥270 mm FL in the 9-RKM study area and, because of uncertainty associated with movement at the lower end of this area, in a truncated portion of the study area encompassing only the lower 6-RKM of Hungry Hollow Creek. The estimated abundance of Arctic graying ≥270 mm FL was 40,952 (95% CI = 29,732–52,732) in the 9-RKM study area and 28,894 (95% CI = 17,975–39,813) in the 6-RKM area. Because precision requirements for these estimates were not met due to low capture probabilities for fish 270–289 mm FL, abundance was also more precisely estimated for Arctic grayling ≥290 mm FL. The estimated abundances of Arctic grayling ≥290 mm FL in the 9-RKM and 6-RKM study areas were 16,356 (95% CI = 14,050–18,663) and 10,416 (95% CI = 8,774–12,058) fish, respectively. Individual length strata abundance estimates are presented in this report. Length compositions for Arctic grayling ≥270 mm FL were very similar in both study areas, with fish 270–289 mm accounting for >60% of the estimated population, whereas larger fish (i.e., fish ≥320 mm FL) accounted for