We investigated the effects of three sea surface oceanographic variables (temperature, salinity, and chlorophyll a) on the abundance of eggs and larvae of two summer‐spawning species in the NW Mediterranean Sea, the anchovy Engraulis encrasicolus and the round sardinella Sardinella aurita, based on data from ichthyoplankton surveys carried out in the 1980s, 2000s, and 2010s. The environmental data showed an increase in seawater temperature and salinity along time, coupled with a decrease in chlorophyll a (proxy for primary production). These long‐term directional changes in environmental conditions helped explain the important reduction observed in the abundance of eggs and larvae of anchovy, as well as shrinking of spawning habitat in this species. At the same time, the probability of occurrence of round sardinella has increased from practically zero in the 1980s to probabilities near 1 along the coastal area of the study region in the two decades of the 21st century. Given that the trends observed in the environmental variables along the three decades of study are expected to continue during the 21st century, as a consequence of climate change, the spawning habitat of anchovy is expected to continue decreasing, while round sardinella habitat can expand. Considering that anchovy is of high commercial importance in NW Mediterranean fisheries, while round sardinella has very low commercial interest, our results show that the viability of small pelagic fisheries in the area may be compromised.

中文翻译：

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地中海西北部两条中上层小鱼产卵栖息地的变化

我们调查了三个海面海洋学变量（温度，盐度和叶绿素a）对西北地中海，夏季cho鱼Engraulis encrasicolus和圆形沙丁鱼沙丁鱼（Sardinella aurita）的两个夏季产卵物种的卵和幼虫的丰度的影响，基于1980年代，2000年代和2010年代进行的鱼鳞浮游动物调查的数据。环境数据显示，海水温度和盐度随时间升高，同时叶绿素a降低。（用于初级生产的代理）。这些环境条件的长期方向变化有助于解释在该物种中大量减少的卵和in鱼幼虫以及产卵栖息地萎缩的重要原因。同时，在21世纪的二十年间，沙丁鱼圆形沙丁鱼发生的可能性从1980年代的几乎为零增加到研究区域沿海地区接近于1的概率。考虑到由于气候变化，预计在整个研究的三十年中在环境变量中观察到的趋势将在21世纪持续下去，预计an鱼的产卵栖息地将继续减少，而沙丁鱼的圆形栖息地可以扩大。考虑到an鱼在西北地中海渔业中具有高度的商业重要性，