Characterization of Senegalese sole, Solea senegalensis, male broodstock in terms of sperm production and quality

Sperm quality and production have never been characterized in Solea senegalensis males. Reproduction in captivity in this species has been obtained mostly with wild-captured animals, because it is common that the F1 generation fails to reproduce. However, there is no information on sperm quality from both types of broodstocks. The aim of the present study was to characterize sperm production and to describe the profiles of spermiation in individual wild-captured males. Also, sperm quality and production were determined in two types of broodstocks established in our facilities; wild-captured and F1 individuals. The males were analyzed for their fluency and identified as fluent or non-fluent. The sperm volume, cell concentration, sperm production and motility were recorded from mid February until mid November in both broodstocks. Results showed that S. senegalensis males can produce motile sperm during all this period, with specific peaks of high spermiation and a high percentage of fluent males. This fact was observed in both male broodstocks. There was a large variability in terms of sperm profiles in males maintained under the same conditions. Sperm volume collected in this species was very small and ranged from 5 to 20 μl in F1 broodstock and 10 to 80 μl in wild-captured broodstock. Cell density ranged from 0.7 to 1.2 × 10⁹ spermatozoa/ml in F1 males to values of 1-2 × 10⁹ spermatozoa/ml for the wild-captured males. Sperm production (total spermatozoa per stripping) was also very low and ranged from 20 × 10⁶ spermatozoa for F1 broodstock to 40-60 × 10⁶ spermatozoa for wild-captured broodstock. Our results demonstrated that sperm production in this species is very low and variable according to the type of males. These results suggest that a previous selection of males according to their fluency, sperm production and provenience (wild-captured or F1) should be taken into account in the establishment of a S. senegalensis broodstock.