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受压力持续攀升，定量评估脆弱鱼类渔业种群的必要性愈发关键，以规避渔业种群耗竭所引发的生态后果。石首鱼科（Sciaenidae，俗称叫姑鱼、鼓鱼）是热带与温带渔业的重要组成类群，且尤其易受捕捞活动影响。其中黑斑叫姑鱼（Protonibea diacanthus）是澳大利亚北部沿海水域中唯一的大型石首鱼类，因其食用价值与可预测的集群行为，成为商业捕捞从业者、休闲垂钓者及原住民传统渔民的目标捕捞物种。该物种的局部种群丰度已出现下降，这凸显了渔业管理者亟需获取精细尺度与大尺度种群连通性相关信息的迫切性。本研究采用三种互补性研究方法，对澳大利亚西北部海域的黑斑叫姑鱼种群结构展开了调查：微卫星标记（microsatellite markers）的遗传变异分析、耳石元素组成（otolith elemental composition）分析，以及寄生虫群落组成（parasite assemblage composition）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（Dampier Peninsula）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位点间存在显著的空间差异，表明单个鱼类在其生命周期内表现出精细尺度的栖息地保真行为。三种技术的互补性阐明了不同空间与时间尺度下的种群连通性模式。本研究认为，需针对精细尺度（数百公里级别）开展渔业种群评估与管理，以应对种群间有限的基因交流问题，并防止该物种出现局部种群灭绝。切实可行的管理方案可包括逐步关闭及开放捕捞区域，以降低捕捞压力。