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首页> 外文期刊>Marine ecology progress series >Benefits of threshold strategies and age-selective harvesting in a fluctuating fish stock of Norwegian spring spawning herring Clupea harengus
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Benefits of threshold strategies and age-selective harvesting in a fluctuating fish stock of Norwegian spring spawning herring Clupea harengus

机译：挪威春季产鱼鲱鱼波动的鱼类种群波动阈值策略和按年龄选择收获的好处

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摘要

The current state of the world's fisheries resources requires further investigation into the means and methods for sustainable use of fish stocks. In this study, I assess the performance of different harvesting strategies on a population model developed for Norwegian spring spawning herring Clupea harengus, a stock historically known as one of the largest and most valuable fish stocks in the world. This stock is further characterized by strong long-term fluctuations in stock size, which considerably complicate successful population management. The results support the use of threshold strategies, where harvesting is only allowed if the population size of the target population is above a predetermined threshold. Threshold strategies are beneficial for maintaining spawning biomass, yield, and prevention of population collapse. The downside of a threshold approach is the fisheries moratoria associated with low stock size. To overcome this, I introduce a precautionary strategy including 2 thresholds for reducing the likelihood and length of moratoria, such that if the population size decreases below an upper threshold, the harvest ratio is decreased in order to achieve fast recovery to the target population size. I also test the effect of changing the timing of fish entering the harvestable stock by means of age-selective harvesting. I show that allowing reproduction, preferably more than once, before the fish become vulnerable to harvesting increases the spawning biomass and yield, and decreases the variability in yield and the risk of stock collapse.
机译：当前世界渔业资源状况需要进一步调查可持续利用鱼类资源的手段和方法。在这项研究中，我评估了针对挪威春季产卵鲱鱼Clupea harengus种群模型开发的不同捕捞策略的性能，该种群历史上被称为世界上最大和最有价值的鱼类种群之一。该种群的进一步特征是种群规模长期强烈波动，这极大地使成功的人口管理复杂化。结果支持阈值策略的使用，其中仅当目标人群的人口规模超过预定阈值时才允许收获。阈值策略对于保持产卵量，产量和防止种群崩溃是有益的。阈值方法的缺点是与种群数量低有关的暂停渔业。为了克服这个问题，我引入了一种预防策略，其中包括2个阈值，以减少暂停执行的可能性和持续时间，这样，如果种群数量减少到上限以下，则收成率就会降低，以便快速恢复到目标种群数量。我还测试了通过按年龄选择的捕捞方式改变鱼类进入可捕捞种群时机的影响。我表明，在鱼类变得容易受到捕捞之前允许繁殖，最好不止一次，这会增加产卵生物量和产量，并降低产量的变异性和种群崩溃的风险。

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