de Casamajor M N, Lecomte-Finiger R, Prouzet P
Laboratoire halieutique d'Aquitaine, Ifremer, Technopole Izarbel Côte Basque, Maison du parc, 64210 Bidart, France.
C R Acad Sci III. 2001 Nov;324(11):1011-9. doi: 10.1016/s0764-4469(01)01378-6.
The embryonic past of glass eels was studied from the interpretation of microstructures registered on otoliths. The aim of this work is to put in evidence possible seasonal modifications of the growth of otoliths so that differences between otoliths of glass eels caught off marine and estuarine environment. So during the season 1999-2000, from November till March, otolith sampling was realised in the southwestern part of France, in an estuarine and coastal zone. We observed a spatial and temporal evolution of proportions of the three various types of otoliths taken into account. Glass eels sampled at sea sometimes have a mark on their otoliths indicating the transition in the estuary, especially at the end of the fishing season. Measures of growth marks of otoliths showed that there were no seasonal differences during phases of the transoceanic migration and the crossing of the continental shelf. The radius of otoliths of glass eels sampled at sea was significantly smaller than those sampled in estuary. These results translated homogeneous environmental modifications met by the various larvae groups during the oceanic crossing and during the principal migration season as well as a turn over of these groups during the transition between marine and continental environment.
通过对耳石上记录的微观结构进行解读，研究了玻璃鳗的胚胎发育历程。这项工作的目的是揭示耳石生长可能存在的季节性变化，以便找出在海洋和河口环境捕获的玻璃鳗耳石之间的差异。因此，在1999 - 2000年期间，从11月到次年3月，在法国西南部的一个河口和沿海区域进行了耳石采样。我们观察了所考虑的三种不同类型耳石比例的时空演变。在海上捕获的玻璃鳗，其耳石有时会有一个标记，表明其进入河口，特别是在捕鱼季节末期。耳石生长标记的测量结果表明，在跨洋洄游和穿越大陆架阶段不存在季节性差异。在海上捕获的玻璃鳗耳石半径明显小于在河口捕获的玻璃鳗。这些结果表明，不同幼体群体在越洋洄游和主要洄游季节遇到的环境变化是一致的，并且在海洋和大陆环境过渡期间这些群体发生了更替。
