Journal Article Inter-annual dynamics of the Barents Sea red king crab (Paralithodes camtschaticus) stock indices in relation to environmental factors

10 ( 4 )  , pp.541 - 552 , 2016-12
Knowledge of relationships between environmental variables and biological processes can greatly improve fisheries assessment and management in commercially important species. We analyzed the effects of environmental factors (climatic indices and water temperature) on the stock characteristics (total population number, number of pre-recruits and number of legal males) of the red king crab (Paralithodes camtschaticus), an introduced species in the Barents Sea. Stock trends in red king crab appear to be related to decadal climate shifts. Abundances were negatively related to the North Atlantic Oscillation index (NAO) in August and positively related to water temperature in late winter–early summer. Total and commercial stock abundance were negatively correlated with the lag-1 Arctic Oscillation index (AO) in August and the lag-2 winter NAO index. The total number of P. camtschaticus was most strongly associated with water temperature in spring and summer and NAO/AO indices in April and May. Lagged NAO indices in February and August (9 or 10 yr) had a positive relationship to the commercial stock of P. camtschaticus. These findings suggest that temperature conditions of current and previous year affect natural mortality of larvae and juvenile red king crabs. Warmer temperature conditions lead to increased biomass of red king crab food items. Negative correlations between climatic indices and the red king crab stocks may be associated with predator pressure on juvenile red king crabs or higher mortality because of predator or parasite pressure and diseases. The associations between stock indices and environmental variables could help better predict recruitment patterns of P. camtschaticus.
バレンツ海に持ち込まれたタラバガニ(Paralithodes camtschaticus)の資源量特性と環境因子について解析した。本種の総個体数及び漁獲対象となる個体数は8月の北大西洋振動指数(North Atlantic Oscillation index)と負の相関を示し、3月~7月の水温と正の相関を示した。また、8月の北極振動指数(Arctic Oscillation index)に対して1年のラグ、冬の北大西洋振動指数に対して2年のラグを持って負の関係を示した。こうした結果から、当該年及び前年の水温条件は、本種の幼生期・若齢期の自然死亡率に影響を及ぼしていることが示唆される。すなわち、暖水温条件は本種の餌生物資源の増加をもたらしているため、生残率が高くなると考えられる。北大西洋振動指数や北極振動指数と本種資源量が負の関係を示すのは、若齢期に対する捕食圧が高くなるためと推察された。環境指数と資源量を関連付けた解析は、漁獲対象資源量の加入過程における精度の高い予測に役立つ。

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