Data from: Strong population structure deduced from genetics, otolith chemistry and parasite abundances explains vulnerability to localised fishery collapse in a large Sciaenid fish, Protonibea diacanthus

As pressure on coastal marine resources is increasing globally, the need to quantitatively assess vulnerable fish stocks is crucial in order to avoid the ecological consequences of stock depletions. Species of Sciaenidae (croakers, drums) are important components of tropical and temperate fisheries and are especially vulnerable to exploitation. The black-spotted croaker, Protonibea diacanthus, is the only large sciaenid in coastal waters of northern Australia where it is targeted by commercial, recreational and indigenous fishers due to its food value and predictable aggregating behaviour. Localised declines in the abundance of this species have been observed, highlighting the urgent requirement by managers for information on fine and broad-scale population connectivity. This study examined the population structure of P. diacanthus across northwestern Australia using three complementary methods: genetic variation in microsatellite markers, otolith elemental composition and parasite assemblage composition. The genetic analyses demonstrated that there were at least five genetically distinct populations across the study region, with gene flow most likely restricted by inshore biogeographic barriers such as the Dampier Peninsula. The otolith chemistry and parasite analyses also revealed strong spatial variation among locations within broad-scale regions, suggesting fine-scale location fidelity within the lifetimes of individual fish. The complementarity of the three techniques elucidated patterns of connectivity over a range of spatial and temporal scales. We conclude that fisheries stock assessments and management are required at fine scales (100’s km) to account for the restricted exchange among populations (stocks) and to prevent localised extirpations of this species. Realistic management arrangements may involve the successive closure and opening of fishing areas to reduce fishing pressure.

随着全球沿海海洋资源所承受的压力与日俱增，对脆弱鱼类种群开展定量评估的重要性愈发凸显，此举旨在避免种群枯竭所引发的生态后果。石首鱼科（Sciaenidae，俗称叫姑鱼、鼓鱼）物种是热带与温带渔业的重要组成类群，且对捕捞活动尤为敏感。双棘原黄姑鱼（*Protonibea diacanthus*）是澳大利亚北部沿海水域唯一的大型石首鱼科物种，因其兼具食用价值与可预测的集群习性，成为商业捕捞、休闲垂钓及原住民渔民的重点捕捞对象。目前已观测到该物种的局部种群丰度出现下降，这凸显了渔业管理者亟需获取关于种群精细尺度与大尺度连通性（population connectivity）的相关信息。本研究采用三种互补分析方法，对澳大利亚西北部海域双棘原黄姑鱼的种群结构展开探究：微卫星标记（microsatellite markers）遗传变异分析、耳石（otolith）元素组成分析以及寄生虫群落（parasite assemblage）组成分析。遗传分析结果显示，研究区域内至少存在5个遗传分化显著的种群，基因交流大概率受到丹皮尔半岛等近岸生物地理屏障的限制。耳石化学与寄生虫分析同样揭示了大尺度区域内不同采样点间存在显著的空间差异，表明该物种的个体在其生命周期内具有精细尺度的位置保真度（location fidelity）。三种技术的互补性共同阐明了不同空间与时间尺度下的种群连通模式。本研究认为，鉴于种群间的基因交流受限，需在精细尺度（百公里级别）开展渔业种群评估与管理工作，以避免该物种出现局部灭绝。切实可行的管理方案可通过对捕捞区域的阶段性关停与开放，来降低捕捞压力。