Spatial and temporal variation in the density of northern cod and a review of hypotheses for the stock's collapse
Spatial and temporal variation in the density of northern cod and a review of hypotheses for the stock's collapse
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DOI：
10.1139/cjfas-53-5-943
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发表时间：
1996-05-01
影响因子：
2.4
通讯作者：
Hutchings, JA
中科院分区：
文献类型：
--
作者：
Hutchings, JA
纽芬兰和拉布拉多海域北部鳕鱼（Gadus morhua）的灭绝与密度和生物量的明确时空变化有关。 1981 年至 1992 年间，低密度研究调查丝束（500 公斤/丝束）比例保持不变（接近 1.5%），直到 1992 年，此后下降至零。向南，种群生物量的时空变化并没有伴随着鳕鱼分布的变化。简单的密度组成模型为观察到的移动和固定渔具捕获率变化、鳕鱼可捕获性随着种群生物量下降而增加以及捕捞死亡率的快速增加提供了生物学基础。一个小而恒定数量的密集鳕鱼聚集体的嵌套聚集模型，每个聚集体都被低密度区域包围并从低密度区域招募，解释了鳕鱼对捕捞的脆弱性如何随着种群生物量的下降而增加。对最近研究的回顾表明，捕捞死亡率过高是北方鳕鱼数量减少的唯一重要原因。预防渔业崩溃可以说取决于本次审查中出现的主要问题：捕捞对被开发鱼类的行为、生活史和种群生物学有何影响？
The collapse of northern cod, Gadus morhua, off Newfoundland and Labrador was associated with clearly defined spatial and temporal changes in density and biomass. Between 1981 and 1992, low density research survey tows (500 kg/tow) remained proportionately constant (similar to 1.5%) until 1992, whereafter they declined to zero. Southward, spatio-temporal changes in stock biomass were unaccompanied by a shift in cod distribution. A simple density composition model provides a biological basis for observed changes in mobile and fixed-gear catch rates, increased catchability of cod with declining stock biomass, and rapid increases in fishing mortality. A nested aggregation model of a small, constant number of dense cod aggregations, each encompassed by, and recruited from, lower density areas, explains how cod vulnerability to fishing can increase with declining stock biomass. A review of recent research identifies excessive fishing mortality as the sole significant cause of northern cod's collapse. Prevention of fishery collapses arguably rests on the dominant question to emerge from this review: what are the effects of fishing on the behaviour, life history, and population biology of exploited fishes?