Department of Oceanography and Coastal Sciences, Louisiana State University, Baton Rouge, LA, USA.
Louisiana Department of Wildlife and Fisheries, Baton Rouge, LA, USA.
Glob Chang Biol. 2021 Jun;27(11):2520-2536. doi: 10.1111/gcb.15568. Epub 2021 Mar 19.
Southern flounder (Paralichthys lethostigma) are a coastal flatfish species that supports recreational and commercial fisheries but are currently experiencing range-wide declines. To quantify the range-wide declines and investigate the role of climate in these declines, fishery-independent sampling data of age-0 flounder were obtained from 34 estuaries representing four states in the Gulf of Mexico (TX, LA, AL, and FL) and three states in the Southeastern United States Atlantic Ocean (FL, SC, and NC) spanning from 1976 to 2019. Generalized additive models (GAM) were used to estimate age-0 recruitment trends. Spatial and temporal synchrony analyses were then conducted using annual GAM-predicted values to determine if trends were similar between estuaries in close proximity, and if declines occurred at the same time. Because the species is dependent on physical transport (i.e., winds and tides) for recruitment, hourly wind speed, wind direction, water temperature, and air temperature were obtained for estuaries with non-zero sampling totals and long-term data sets. Only six estuaries showed significant relationships between age-0 flounder indices and growing degree days. However, all estuaries with wind data showed significant relationships between age-0 flounder indices and hourly summed wind speed. Southern flounder also have environmental sex determination, meaning warming estuaries could also account for population changes and declines. We document that water temperatures in the same space and time where southern flounder sexually determine are warmer now than even a decade ago, which could masculinize populations and substantially change population demographics. These results illustrate the vulnerability of estuarine finfish populations to climate change and increased climate variability. Understanding how climate acts on southern flounder biology may help managers respond to and prevent fishery collapses.
南方比目鱼（Paralichthys lethostigma）是一种沿海比目鱼，支持休闲和商业渔业，但目前正在经历范围广泛的减少。为了量化范围广泛的减少，并研究气候在这些减少中的作用，从 1976 年到 2019 年，从代表墨西哥湾四个州（德克萨斯州、路易斯安那州、阿拉巴马州和佛罗里达州）和美国东南部大西洋三个州（佛罗里达州、南卡罗来纳州和北卡罗来纳州）的 34 个河口获得了年龄为 0 的比目鱼的非依赖性渔业抽样数据。使用广义加性模型（GAM）估计了年龄为 0 的比目鱼的招募趋势。然后使用年度 GAM 预测值进行空间和时间同步分析，以确定相邻河口的趋势是否相似，以及是否同时发生减少。由于该物种依赖于物理输送（即风和潮汐）进行繁殖，因此为有非零采样总数和长期数据集的河口获取了每小时风速、风向、水温和气温。只有六个河口显示了年龄为 0 的比目鱼指数与生长度日之间存在显著关系。然而，所有有风数据的河口都显示了年龄为 0 的比目鱼指数与每小时总和风速之间存在显著关系。南方比目鱼也具有环境性别决定，这意味着变暖的河口也可能导致种群变化和减少。我们记录到，南方比目鱼在同一空间和时间进行性决定的水温比十年前更热，这可能会使种群雄性化，并大大改变种群人口统计学特征。这些结果说明了河口鱼类种群对气候变化和气候变异性增加的脆弱性。了解气候如何作用于南方比目鱼的生物学特性可能有助于管理者应对和防止渔业崩溃。
