Condition and reproductive strategy of the Argentina sphyraena, a cold-water species in the Mediterranean Sea

We evaluate the condition and reproductive status of the lesser silver smelt, Argentina sphyraena in the north-western Mediterranean Sea. We describe for the first time several life history traits of this species, i.e. condition, reproductive cycle, fecundity, breeding strategy, oocyte recruitment and egg quality, and evaluate the links between these traits. We also contrast condition and reproduction parameters in two study areas with different environmental conditions: the Gulf of Lion and the Balearic Sea. Our results indicate that A. sphyraena is a capital breeder with group-synchronous oocyte development and determinate fecundity. Energy requirements for reproduction are mostly met by lipids stored in the mesentery which is the main fat deposit and a good indicator of condition; this means that condition can be estimated visually and easily using a fat scaling technique. Our results show that, in terms of condition and reproduction, this species performs better in the colder and more productive Gulf of Lion than in the warmer and less productive Balearic Sea, as evidenced by the amount of stored energy and reproductive strategy. These findings suggest that suboptimal environmental conditions may have a negative impact on the condition and reproduction strategy of cold-water species, which will ultimately affect their abundance and distribution.