The Tanner Crab Off Southwestern Kamchatka: Fishery, Stock Condition, and Specifics of Assessment

This article presents the results of the current stage of a study of the Tanner crab, Chionoecetes bairdi, which inhabits waters off the southwestern Kamchatka Peninsula coast and is harvested in the Sea of Okhotsk within the Kamchatka–Kuril fishery subzone. The stock dynamics since 2001 are analyzed with special focus on the problems of its assessment and forecast related to its biological features associated with the terminal molt. Since 2010, data have been collected that allow one to distinguish between small-clawed and large-clawed Tanner crab recruits near the southwestern Kamchatka coast; an algorithm for division into such groups has been developed. It has become possible to calculate the probability that a particular size group of small-clawed males undergoes the terminal molt and are recruited to the fishery stock. Two peaks in the total abundance of Tanner crab males were observed during the period, in 2005–2006 and 2020–2022. The Tanner crab fishery ban in the Kamchatka–Kuril fishery subzone in 2019–2020 was the result of a population abundance decline in the 2 preceding years. The fishery was resumed in 2021 after the full recovery of the population. Possible causes for the underestimation of crab recruitment related to both the biological features of the species and methodological issues are discussed. The results of recent studies have convincingly shown that the Tanner crab population reached its historical peak of abundance in 2020–2022, and currently the most abundant population of this species inhabits the Kamchatka–Kuril fishery subzone. The Tanner crab fishery is characterized by high percentage of the total allowable catch and has been in good condition for the last 3 years.