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

美洲鳗鲡（Anguilla rostrata）在L.安大略，由于从马尾藻海产卵地抵达的幼鳗急剧减少。阿尔湖安大略鳗鱼是雌性的，它们是该物种中最大和最多产的雌性。因此，它们的损失将影响整个物种的地位，因为鳗鱼只作为一个种群产卵。这些影响在关闭L。安大略省的渔业减少了50%以上，魁北克省的渔业减少了50%以上，整个N.美国参考鳗鱼在淡水生长过程中积累的化学物质是鳗鱼胚胎从马尾藻迁移到淡水中时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L.安大略。我们的目标是评估鳗鱼在其生长和成熟过程中是否积累了足够的化学污染物，导致胚胎毒性，并估计污染物可能会影响鳗鱼招聘。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中收集新鲜和存档的鳗鱼样本。鳗鱼将被分析已知的胚胎毒性化学物质的浓度，如氯化和溴化有机化合物，硒和烷基锡。提取的化学品的毒性将通过一系列使用培养中的鱼胚胎和鱼细胞的测试进行评估。纳入存档样本和关于化学品对其他鱼类影响的大量文献，将有助于对化学品对鳗鱼繁殖的风险进行回顾性评估。利用这些数据，我们会就不同生境是否适合重新放养幼鳗、化学品管制的优先次序，以及对人类消费者的潜在危害，向渔业管理人员提供意见。由于鳗鱼的价值很高，而且成熟时间很长（7-30年），因此现在就必须进行这项研究，以帮助避免五大湖鳗鱼的完全消失。

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.