Role of Oceanic Fronts in the Distribution and Reproductive Strategy of American Eels (Anguilla Rostrata)

长期以来，美洲和欧洲鳗鱼的产卵区域和海洋迁徙线索一直是个谜。由于幼鳗幼体直接集中在马尾藻海北大西洋副热带辐合带以南，因此推测成熟鳗鱼停止迁徙并在该锋面附近产卵，并利用该锋面的物理或生物特征进行定位。这项研究将直接测试(1)成熟的成年美洲鳗是否集中在额区或紧邻额区以南，以及(2)成鳗的精细垂直和水平分布如何与额区和邻近水域的特征具体相关。将使用定量水声采样来识别适当强度的回声作为鳗鱼，并绘制其分布模式和密度图。将使用有针对性的中水拖网捕鱼、来自远程操作工具的视频、以成熟圈养鳗鱼为诱饵的陷阱，以及对卵和新孵化的幼体进行精细采样，以验证目标是否真的是鳗鱼。将使用水声数据、水中拖网以及温度和盐度剖面来描述锋面的生物和物理特征。这项研究将一种独特的、远距离迁徙的鱼类在公海上的产卵与特定的海洋学特征联系起来。

The spawning area and oceanic migratory cues for American and European eels have long remained enigmatic. Because young eel larvae are concentrated immediately to the south of the North Atlantic Subtropical Convergence in the Sargasso Sea, it is hypothesized that mature eels cease migration and spawn near this front and use physical or biological features of the front for orientation. This research will directly test (1) whether maturing adult American eels are concentrated in, or immediately to the south of, the frontal zone, and (2) how the fine-scale vertical and horizontal distributions of adults are related specifically to characteristics of the frontal zone and adjacent waters. Quantitative hydroacoustic sampling will be used to identify echoes of appropriate strength to be eels and to map their distributional patterns and densitites. Aimed midwater trawling, video from a remotely operated vehicle, traps baited with mature captive eels, and fine-scale sampling of eggs and newly hatched larvae will be used to verify whether targets are actually eels. Hydroacoustic data, midwater trawling, and profiles of temperature and salinity will be used to characterize the biological and physical features of the front. This research links open-ocean spawing of a physiologically unique, long-distance migrating fish to a specific oceanographic feature.