Data from: Impacts of predator depletion by fishing on the biomass and diversity of non-target reef fish communities

An understanding of the indirect effects of fishing on predator-prey relationships is required for the development of valid multispecies yield models for reef fisheries and for determining the factors governing fish community structure at larger scales. We used an underwater visual census technique to examine the indirect effects of fishing on the biomass and diversity (species richness) of reef fishes in a series of ten traditional Fijian fishing grounds (qoliqoli) subject to a range of fishing intensities. All members of the families Chaetodontidae (butterflyfishes), Labridae (wrasses), Lutjanidae (snappers), Mullidae (goatfishes), Scaridae (parrotfishes) and the sub-family Epinephelinae (groupers and coral trout) which could be reliably identified were censused. Each species censused was assigned to one of three trophic groups: herbivore, invertebrate feeder or piscivore. The biomass of all piscivorous fishes and of large (>30 cm) piscivorous fishes differed significantly between qoliqoli and was significantly correlated with fishing intensity. However, the biomass of piscivorous fishes was not correlated with the biomass or diversity of their potential prey (which were not targeted by the fishery). This suggested that the indirect effects of fishing did not have an important bearing on fish diversity or biomass and that predation by the target species did not play an important role in structuring these Fijian reef fish communities. The results contrast with those from a number of studies at smaller scales and provided further indications that the structure of reef fish communities is not governed by a single dominant process, but by a range of processes which operate on different scales in different circumstances.

欲构建适用于礁岩渔业的可靠多物种产量模型，并明晰大尺度下鱼类群落结构的调控因子，亟需厘清捕捞对捕食者-猎物关系的间接影响。本研究采用水下视觉普查技术，探究捕捞对10处斐济传统捕捞海域（qoliqoli）内礁岩鱼类生物量与多样性（物种丰富度）的间接影响，这些海域的捕捞强度存在梯度差异。研究对可稳定识别的蝴蝶鱼科（Chaetodontidae，蝴蝶鱼）、隆头鱼科（Labridae，隆头鱼）、笛鲷科（Lutjanidae，笛鲷）、羊鱼科（Mullidae，羊鱼）、鹦哥鱼科（Scaridae，鹦嘴鱼）以及石斑鱼亚科（Epinephelinae，石斑鱼与珊瑚鳟）的所有物种开展了普查。所有纳入普查的鱼类物种均被划分为三大营养功能群：植食性类群、无脊椎动物食性类群与食鱼性鱼类（piscivore）。不同斐济传统捕捞海域间，所有食鱼性鱼类以及体长大于30cm的大型食鱼性鱼类的生物量均存在显著差异，且其生物量与捕捞强度呈显著相关关系。然而，食鱼性鱼类的生物量与其潜在猎物种群的生物量及多样性并无显著关联，而这些猎物并非本次渔业的捕捞目标物种。该结果表明，捕捞的间接影响并未对礁岩鱼类的多样性与生物量产生显著作用，且目标捕捞物种的捕食作用在塑造这些斐济礁岩鱼类群落结构中未发挥关键调控功能。本研究结果与诸多小尺度相关研究的结论存在差异，同时进一步证实：礁岩鱼类群落的结构并非由单一主导过程所调控，而是由一系列在不同情境下以不同尺度运作的生态过程共同塑造。