Reproductive biology of female humpback whitefish Coregonus pidschian in the Chatanika River, Alaska

Summary Humpback whitefish Coregonus pidschian are found throughout Alaska and support both subsistence and personal‐use fisheries. Long‐term sustainability of these fisheries requires an understanding of life‐history characteristics and reproductive biology to provide fisheries managers with the tools required for science‐based management. The objective of this study was to examine the reproductive characteristics of humpback whitefish in the Chatanika River, Alaska, from late August through September 2008. Absolute fecundity, relative fecundity, gonadosomatic index (GSI), relative egg size, and age were examined for 60 female humpback whitefish. Mean absolute fecundity was 45 000 eggs female−1 (range, 11 747–108 426 eggs female−1) and was positively related to both fork length (r2 = 0.74) and wet weight (r2 = 0.83). Gonadosomatic index values averaged 15.5% (range, 6.4–23.7%). Relative fecundity was positively related to GSI (r2 = 0.76) and showed a positive relationship with age until ages 15–20 before declining thereafter. Relative egg size was inversely related to GSI (r2 = 0.38) and age (r2 = 0.22) for female humpback whitefish. The results of our study provide information that will allow for better management of the personal use fishery for humpback whitefish in the Chatanika River and increase our understanding of the reproductive biology of this species throughout its geographic distribution.