Temperate marine protected area provides recruitment subsidies to local fisheries

The utility of marine protected areas (MPAs) as a means of protecting exploited species and conserving biodiversity within MPA boundaries is supported by strong empirical evidence. However, the potential contribution of MPAs to fished populations beyond their boundaries is still highly controversial; empirical measures are scarce and modelling studies have produced a range of predictions, including both positive and negative effects. Using a combination of genetic parentage and relatedness analysis, we measured larval subsidies to local fisheries replenishment for Australasian snapper (Chrysophrys auratus: Sparidae) from a small (5.2 km2), well-established, temperate, coastal MPA in northern New Zealand. Adult snapper within the MPA contributed an estimated 10.6% (95% CI: 5.5-18.1%) of newly settled juveniles to surrounding areas (approx. 400 km2), with no decreasing trend in contributions up to 40 km away. Biophysical modelling of larval dispersal matched experimental data, showing larvae produced inside the MPA dispersed over a comparable distance. These results demonstrate that temperate MPAs have the potential to provide recruitment subsidies at magnitudes and spatial scales relevant to fisheries management. The validated biophysical model provides a cost-efficient opportunity to generalize these findings to other locations and climate conditions, and potentially informs the design of MPA networks for enhancing fisheries management.

海洋保护区（marine protected areas，MPAs）作为保护受开发物种、在其辖区内保护生物多样性的手段，其效用已有坚实的实证研究支撑。然而，MPAs对其辖区外捕捞种群的潜在贡献仍极具争议：相关实证测算十分匮乏，而模型研究得出的预测结果跨度较大，涵盖正向与负向两类效应。本研究结合遗传亲子关系分析与亲缘关系分析方法，对新西兰北部一处面积5.2平方千米、设立已久且运行成熟的温带近岸海洋保护区内的澳州鲷（Australasian snapper，学名Chrysophrys auratus：鲷科Sparidae）展开研究，测算其幼体对周边渔业种群补充的补给贡献。研究估算显示，该保护区内的成年澳州鲷可为周边约400平方千米海域内新定居的幼鱼个体贡献10.6%的比例（95% CI: 5.5-18.1%），且在40千米范围内，贡献量未随距离增加呈现下降趋势。幼体扩散的生物物理模型模拟结果与实验数据吻合，表明该保护区内产出的幼体可扩散至相近的距离范围。上述结果证明，温带海洋保护区具备为渔业管理提供符合规模与空间尺度要求的种群补充补给的潜力。经验证的生物物理模型可实现成本高效的推广，将本研究发现推广至其他区域与气候条件下，或可为设计用于强化渔业管理的海洋保护区网络提供决策参考。