Quantifying the projected impact of the South African sardine fishery on the Robben Island penguin colony
Quantifying the projected impact of the South African sardine fishery on the Robben Island penguin colony
复制标题
量化南非沙丁鱼渔业对罗本岛企鹅栖息地的预计影响
DOI：
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
É. Plagányi
中科院分区：
文献类型：
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作者：
W. Robinson;D. Butterworth;É. Plagányi
需要定量方法来评估捕食者依赖的渔业饲料物种的生态效应。20世纪90年代，罗本岛殖民地的非洲企鹅Spheniscus demersus数量上升，同时沙丁鱼Sardinops sagax和凤尾鱼Engraulis encrasicolus丰度显着增加，但在2000年代，由于沙丁鱼遭受了一系列不良的招募，数量明显下降。建立了一个适合于企鹅换羽计数和标记企鹅再观察的种群动力学模型，该模型将成年企鹅的年死亡率与当地沙丁鱼生物量联系起来。捕食者-猎物的相互作用是最好的解释沙丁鱼-企鹅死亡率的关系，平均企鹅生存下降，只有当当地沙丁鱼生物量小于约四分之一的最大观察。结果表明，1990年代殖民地的快速增长主要是由移民推动的。企鹅的预测是通过与未来的沙丁鱼丰度相联系而产生的，该沙丁鱼丰度是根据用于为这些沙丁鱼和鱼渔业设定渔获量限制的业务管理程序预测的，并与没有捕捞的同等情景进行比较。结果表明，捕鱼可能对企鹅的影响相对较小，特别是与沙丁鱼种群空间分布可变所产生的不确定性相比。
Quantitative methods are needed to evaluate the ecological effects of fishing forage species upon which predators depend. African penguin Spheniscus demersus numbers at the Robben Island colony rose during the 1990s co-incidental with a marked increase in sardine Sardinops sagax and anchovy Engraulis encrasicolus abundances, but decreased appreciably during the 2000s as sardine suffered a series of poor recruitments. A population dynamics model is developed which relates penguin adult annual mortality to local sardine biomass, and is fit to penguin moult counts and re-sightings of tagged penguins. The predator–prey interaction is best explained by a sardine–penguin mortality relationship with average penguin survival decreasing only when the local sardine biomass is less than approximately one-quarter of the maximum observed. Results suggest that the rapid growth of the colony during the 1990s was driven primarily by immigration. Penguin projections are generated by linking to future sardine abundances predicted under the operational management procedure used to set catch limits for these sardine and anchovy fisheries, and compared with equivalent scenarios without fishing. Results indicate that fishing is likely to have a relatively small impact on penguins, especially when compared with uncertainties that arise from the variable spatial distribution of the sardine population.