Australian Rivers Institute - Coasts and Estuaries, School of Environment and Science, Griffith University, Nathan, Qld, Australia.
Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tas., Australia.
Glob Chang Biol. 2021 Mar;27(6):1214-1225. doi: 10.1111/gcb.15472. Epub 2020 Dec 19.
Marine heatwaves are increasing in frequency and intensity, and indirectly impacting coral reef fisheries through bleaching-induced degradation of live coral habitats. Marine heatwaves also affect fish metabolism and catchability, but such direct effects of elevated temperatures on reef fisheries are largely unknown. We investigated direct and indirect effects of the devastating 2016 marine heatwave on the largest reef fishery operating along the Great Barrier Reef (GBR). We used a combination of fishery-independent underwater census data on coral trout biomass (Plectropomus and Variola spp.) and catch-per-unit-effort (CPUE) data from the commercial fishery to evaluate changes in the fishery resulting from the 2016 heatwave. The heatwave caused widespread, yet locally patchy, declines in coral cover, but we observed little effect of local coral loss on coral trout biomass. Instead, a pattern of decreasing biomass at northern sites and stable or increasing biomass at southern sites suggested a direct response of populations to the heatwave. Analysis of the fishery-independent data and CPUE found that in-water coral trout biomass estimates were positively related to CPUE, and that coral trout catch rates increased with warmer temperatures. Temperature effects on catch rates were consistent with the thermal affinities of the multiple species contributing to this fishery. Scaling-up the effect of temperature on coral trout catch rates across the region suggests that GBR-wide catches were 18% higher for a given level of effort during the heatwave year relative to catch rates under the mean temperatures in the preceding 6 years. These results highlight a potentially large effect of heatwaves on catch rates of reef fishes, independent of changes in reef habitats, that can add substantial uncertainty to estimates of stock trends inferred from fishery-dependent (CPUE) data. Overestimation of CPUE could initiate declines in reef fisheries that are currently fully exploited, and threaten sustainable management of reef stocks.
海洋热浪的频率和强度正在增加，并通过导致活珊瑚栖息地白化的退化，间接影响珊瑚礁渔业。海洋热浪还会影响鱼类新陈代谢和可捕捞性，但升高的温度对珊瑚礁渔业的这种直接影响在很大程度上尚未可知。我们调查了破坏性的 2016 年海洋热浪对大堡礁（GBR）沿线最大的珊瑚礁渔业的直接和间接影响。我们结合了对珊瑚石斑鱼生物量（Plectropomus 和 Variola 属）的非渔业独立水下普查数据和商业渔业的单位捕捞努力量渔获数据（CPUE），评估了 2016 年热浪对渔业的影响。热浪导致了珊瑚覆盖范围的广泛但局部斑块状减少，但我们几乎没有观察到局部珊瑚损失对珊瑚石斑鱼生物量的影响。相反，北部地点的生物量减少和南部地点的稳定或增加的生物量模式表明种群对热浪的直接反应。对非渔业独立数据和 CPUE 的分析发现，水中珊瑚石斑鱼生物量估计值与 CPUE 呈正相关，并且珊瑚石斑鱼的捕捞率随温度升高而增加。温度对捕捞率的影响与对该渔业有贡献的多个物种的热亲和性一致。根据温度对珊瑚石斑鱼捕捞率的影响在整个地区的影响，在热浪年份，相对于前 6 年的平均温度下的捕捞率，整个 GBR 的捕捞量在给定的努力水平下增加了 18%。这些结果突出表明，海洋热浪对珊瑚礁鱼类的捕捞率有潜在的重大影响，而与珊瑚礁栖息地的变化无关，这可能会给从渔业依赖（CPUE）数据推断的种群趋势估计带来很大的不确定性。对 CPUE 的高估可能会导致目前已充分开发的珊瑚礁渔业的衰退，并威胁到珊瑚礁种群的可持续管理。
