Are chemical contaminants contributing to the recruitment failure of American eel (Anguilla rostrata)

由于马尾藻海产卵地的幼鳗数量急剧减少，安大略省L.安大略省的美洲鳗鱼(Anguilla Rostrata)正处于局部灭绝的边缘。所有的安大略省鳗鱼都是雌性，是该物种中体型最大、繁殖能力最强的雌性。因此，它们的丧失将影响整个物种的地位，因为鳗鱼只作为一个种群产卵。这些影响已经在安大略省L.L渔业的关闭、魁北克渔业的50%以上的减少以及整个北美许多鳗鱼渔业的下降中得到明显体现。鳗鱼在淡水生长过程中积累的化学物质可能是鳗鱼胚胎从马尾藻迁移到淡水中过早死亡的一个可能原因。在淡水中生长期间，鳗鱼成为顶级捕食者，积累多氯联苯和多氯二恶英等化合物，其浓度与导致安大略省L.Ontario湖鲑鱼繁殖失败的浓度相似。我们的目标是评估鳗鱼在生长和成熟过程中是否积累了足够的化学污染物来造成胚胎毒性，并估计污染物可能影响鳗鱼招募的时间。我们的大学和政府科学家团队，包括美国和欧洲的同事，将从参考和受污染的生态系统收集新鲜和存档的鳗鱼样本。这些鳗鱼将被分析已知对胚胎有毒的化学物质的浓度，如氯化和溴化有机化合物、硒和烷基锡。提取的化学物质的毒性将通过使用鱼类胚胎和培养中的鱼类细胞进行一系列测试来评估。纳入关于化学品对其他鱼类物种的影响的存档样本和广泛的文献，将使我们能够对化学品对鳗鱼繁殖的风险进行回顾评估。利用这些数据，我们将就不同栖息地重新放养幼鳗的适宜性、化学控制的优先次序以及对人类消费者的潜在危险向渔业管理人员提供建议。因为鳗鱼的价值很高，成熟的时间很长(7-30年)，所以现在就进行这项研究是至关重要的，以帮助避免五大湖鳗鱼的完全丧失。

The American eel (Anguilla rostrata) is on the verge of local extinction in L. Ontario, due to a precipitous decline in the arrival of juvenile eels from their spawning grounds in the Sargasso Sea. All L. Ontario eels are female, and they are the largest and most fecund females of the species. Hence, their loss will affect the status of the entire species because eels spawn as only one population. These impacts are already apparent in the closure of the L. Ontario fishery, a reduction by more than 50% of the fishery in Quebec, and declines in many eel fisheries throughout N. America. Chemicals accumulated by eels during their freshwater growth are one likely cause of premature mortality of eel embryos as they migrate from the Sargasso to fresh water. During their growth in fresh water, eels become top predators, accumulating compounds such as PCBs and polychlorinated dioxins to concentrations similar to those causing reproductive failure of lake trout in L. Ontario. Our objectives are to evaluate if eels accumulate sufficient chemical contaminants during their growth and maturation to cause embryo toxicity, and to estimate when contaminants might have affected eel recruitment. Our team of university and government scientists, including colleagues in the US and Europe, will collect fresh and archived samples of eels from reference and contaminated ecosystems. The eels will be analyzed for concentrations of chemicals known to be embryo-toxic, such as chlorinated and brominated organic compounds, selenium, and alkyl tin. The toxicity of extracted chemicals will be assessed with a battery of tests using fish embryos and fish cells in culture. The inclusion of archived samples and an extensive literature on chemical effects on other fish species will allow a retrospective assessment of the risks of chemicals to eel reproduction. Using these data, we will advise fisheries managers about the suitability of different habitats for re-stocking with juvenile eels, priorities for chemical controls, and potential hazards to human consumers. Because eels are highly valued and have a long time to maturity (7-30 years), it is essential that this research be done now, to help avoid a complete loss of eels from the Great Lakes.