Implications of divergent cortisol stress responsiveness in male striped bass (Morone saxatilis)

The aim of this study was to identify whether differences exist in reproductive and growth performance of male striped bass selected for high cortisol stress responsiveness (HCR) and low cortisol stress responsiveness (LCR), when exposed to standardized stress challenges before and during the spawning season. HCR (n = 10) and LCR (n = 10) were identified out of a population of 67 three-year-old striped bass males. Although no significant differences in weight, length, or coefficient of condition were found between HCR and LCR, HCR had a significantly greater specific growth rate when compared to LCR. Circulating levels of testosterone and 11-ketotestosterone were significantly higher in HCR than in LCR before and during the spawning season. HCR also had more fish spermiating across all sample dates compared to LCR. These results suggest that striped bass selected for high cortisol stress responsiveness have better reproductive and growth performance than fish selected for lower cortisol stress responsiveness.