Evaluation of a Fishery Resource Response to a Net-Use Restriction in Saipan Lagoon, Commonwealth of the Northern Mariana Islands Pacific Science

A wide variety of fishing methods is used to harvest coral-reef fishes worldwide, with increasing concerns regarding long-term sustainability. As such, there is a need to determine the degree to which specific fishing methods influence coral-reef fish resources. In 2004 the Commonwealth of the Northern Mariana Islands instituted restrictions on use of gill, drag, and surround nets, limiting use to special exemption for annual fiestas. Historical creel survey data and data from net-use exemptions were reviewed and underwater visual census surveys conducted in southern Saipan Lagoon to assess changes in abundance and biomass from 2004 to 2011. Generalized linear modeling results showed numerical increases in four reef fish families, including Labridae, Scaridae, Mullidae, and the primary target of exempted net-fishing events, Lethrinidae. In addition, mean increases in total reef fish biomass were observed from 2004 to 2011. Positive changes in abundance and biomass of certain coral-reef fish families suggest that decreased fishing mortality via gear restrictions on use of nets can be a useful tool toward the goal of reef fish sustainability in coral-reef ecosystems.

全球范围内，人们采用多种捕捞方式采收珊瑚礁鱼类，各界对其长期可持续性的担忧与日俱增。有鉴于此，亟需明确特定捕捞方式对珊瑚礁鱼类资源的影响程度。2004年，北马里亚纳群岛联邦出台了针对刺网、拖网及围网使用的限制措施，仅允许在年度庆典活动的特殊豁免场景下使用此类网具。研究人员梳理了历史渔获统计调查数据与网具使用豁免相关数据，并在塞班礁湖南部开展水下视觉普查，以评估2004年至2011年间珊瑚礁鱼类的丰度与生物量变化。广义线性模型（Generalized Linear Modeling）结果显示，四个礁栖鱼类科的种群数量出现增长，分别为隆头鱼科（Labridae）、鹦嘴鱼科（Scaridae）、羊鱼科（Mullidae），以及豁免网捕作业的主要目标类群裸颊鲷科（Lethrinidae）。此外，2004年至2011年间，礁栖鱼类总生物量的均值也呈现上升趋势。部分珊瑚礁鱼类科的丰度与生物量正向变化表明，通过限制网具使用以降低捕捞死亡率，可作为实现珊瑚礁生态系统中礁栖鱼类可持续发展目标的有效手段。