To the stock abundance assessment of Tanner crab in the Kamchatka-Kurile subzone

Tanner crab Chionoecetes bairdi is the highly valuable object of commercial fishery dwelling in the seas surrounding Kamchatka Peninsula. Its landings started at the southeastern coast of Kamchatka in early 1980s and continued till 2009, when the fishery was stopped by reasons independent on the stock state. It was launched again in 2017. Now the species is landed mostly in the Petropavlovskaya fishery subzone (62 % of the total allowable catch of tanner crab in Russia in 2019), whereas its stocks at southwestern Kamchatka and in the northwestern Bering Sea are rather low. Modern condition of the tanner crab population and its distribution at southeastern Kamchatka are considered on the data of the trap surveys conducted in spring and summer of 2012 and 2018. Between these years, commercial males of these species spread wider at southeastern Kamchatka and formed commercial aggregations in the northern Avachinsky Bay and in the southern and central parts of the Kronotsky Bay, but were rare southward from Cape Povorotny. They became larger: while size of the males varied in the range 50–170 mm in both years, the males with the carapace width < 120 mm prevailed in 2012, but the large-sized males with commercial size were more numerous in 2018. Percentage of the females in the catches was low both in 2012 and 2018 that is typical for the trap catches. The crabs at the 3rd stage of molting dominated both in May and August of 2012 and 2018. Injury level of the commercial males was rather high and increased from 2012 to 2018 in 8 %. Good current condition of the tanner crab population at southeastern Kamchatka is concluded.

Current State of Stock for Tanner Crab Chionoecetes Bairdi Rathbun, 1924 (Crustacea, Decapoda) at the South-Eastern Coast of Kamchatka

Mikhailova¹

2019

Application of machine learning methods to restore size-sex composition in catches of snow crab

Chernienko,

Slizkin,

Kulik

2024

Impact of environmental conditions on spatial distribution of size-sex groups is described statistically for snow crab Chionoecetes opilio. Based on the relationships identified, absolute values of catches are calculated for each such group. Machine learning approach is implemented for the feature engineering and statistical relationships evaluation. The approach can be adopted for other benthic stocks.

Tanner crab at southwestern Kamchatka: fishing, stock condition and specifics of the assessment

Ivanov

2024

Results of the current stage of research on tanner crab at the southwestern coast of Kamchatka, harvested in the Kamchatka-Kuril fishing subzone are presented. The stock dynamics since 2001 is analyzed, with special attention to its assessing and forecasting. Features of the crab biology associated with terminal molting are described. The algorithm for separation of the tanner crab recruits into morphometrically mature and immature males is developed that allows to calculate probability for a particular size group of morphometrically immature males to undergo the terminal molt and join to the commercial stock. This algorithm is applied for the data collected at southwestern Kamchatka since 2010. Two peaks in total male abundance of tanner crab were observed in 2005–2006 and 2020–2022. Landing of this species was banned in the Kamchatka-Kuril fishing subzone in 2019–2020, as the result of the local population abundance drop in the previous two years, but was resumed in 2021 after its full restoration. Possible reasons for underestimation of the crab recruitment are discussed, related both with features of the species biology and methodological problems. The population in the Kamchatka-Kuril fishing subzone is currently the most abundant for tanner crab, and this stock in 2020–2022 has reached the historical peak. The fishing of tanner crab in the last three years is distinguished by high catches and high rate of the total allowable catch (TAC) utilization.