University of Guam Marine Laboratory, Mangilao, Guam.
Chuuk Department of Marine Resources, Weno, Chuuk, Federated States of Micronesia.
PLoS One. 2018 May 31;13(5):e0198068. doi: 10.1371/journal.pone.0198068. eCollection 2018.
The consistent supply of fresh fish to commercial markets may mask growing fishing footprints and localized depletions, as fishing expands to deeper/further reefs, smaller fish, and more resilient species. To test this hypothesis, species-based records and fisher interviews were gathered over one year within a large, demand-driven coral-reef fishery in Chuuk, Micronesia. We first assessed catch statistics with respect to high windspeeds and moon phases that are known to constrain both catch and effort. While lower daily catch success was predicted by higher windspeeds and greater lunar illumination, total daily landings fluctuated less than fishing success across environmental gradients. Instead, daily landings were mainly driven by the number of flights from Chuuk to Guam (i.e., international demand). Given that demand masked local drivers of overall catch volume, we further evaluated species-based indicators of fisheries exploitation. Most target species (75%) had either a positively skewed size distribution or proportional contributions that were dependent upon favorable conditions (i.e. season and moon phases). Skewed size distributions indicated truncated growth associated with fishing mortality, and in turn, suggested that size-based management policies may be most effective for these species. In contrast, environmentally-constrained catch success indicated species that may be more susceptible to growing fishing footprints and may respond better to gear/quota/area policies compared to size policies. Species-based responses offered a simplified means to combine species into fisheries management units. Finally, a comparison of commercial and subsistence landings showed higher vulnerability to fishing among species preferentially targeted by commercial fisheries, offering new insights into how commercial harvesting can disproportionately impact resources, despite having lower annual catch volumes.
商业市场对新鲜鱼类的稳定供应可能掩盖了渔业足迹的不断扩大和局部资源枯竭,因为捕鱼活动已扩展到更深/更远的珊瑚礁、更小的鱼类和更有弹性的物种。为了验证这一假设,我们在密克罗尼西亚楚克的一个大型需求驱动型珊瑚礁渔业中,用了一年的时间收集了基于物种的记录和渔民访谈。我们首先评估了与已知限制渔获量和捕捞努力的高风速和月相有关的渔获统计数据。虽然更高的风速和更大的月光照度预测每日渔获成功率较低,但在环境梯度上,总日登陆量的波动小于渔获成功率。相反,每日登陆量主要受楚克飞往关岛的航班数量(即国际需求)的驱动。由于需求掩盖了整体渔获量的本地驱动因素,我们进一步评估了基于物种的渔业开发指标。大多数目标物种(75%)的体型分布呈正偏态或比例贡献取决于有利条件(即季节和月相)。偏态体型分布表明与捕捞死亡率相关的生长中断,这反过来表明基于体型的管理政策可能对这些物种最有效。相比之下,受环境限制的渔获成功率表明,一些物种可能更容易受到捕捞足迹的扩大影响,并且可能对渔具/配额/区域政策的响应比体型政策更好。基于物种的响应提供了一种将物种组合成渔业管理单位的简化方法。最后,对商业和生计登陆量的比较表明,商业渔业优先目标的物种更容易受到捕捞的影响,这为商业捕捞如何尽管年捕捞量较低,但仍能不成比例地影响资源提供了新的见解。