Female age at maturity and fecundity in Atlantic Striped Bass

Objective

Female age at maturity and fecundity for the Atlantic stock of Striped Bass Morone saxatilis were estimated using histological methods and image analysis.

Methods

Ovaries were obtained from surveys encompassing the spring spawning season (March–July; n = 343), primarily from the Chesapeake Bay, and in the fall months (September–December; n = 85), primarily from the Atlantic coast. Histological examination of oocytes revealed some Striped Bass in intermediate stages of maturation during the spawning season. These individuals were identified as undergoing pubertal development, defined as the transition from the juvenile stage to first sexual maturity. Pubertal development was characterized by ovaries containing a population of enlarged, lipid-filled oocytes but noticeably lacking vitellogenin-derived yolk globules during the spawning season, and those ovaries were classified as immature. Toward the end of the spawning season, increasing proportions of Striped Bass with unspawned ovaries and oocytes undergoing total atresia were observed.

Result

The female age and length at 50% maturity in Atlantic Striped Bass based on spring samples were 5.5 years and 609 mm total length, respectively. Fecundity was determined gravimetrically via image analysis of ovarian tissue samples from spawning capable individuals (n = 67). Potential annual fecundity was found to exhibit hyperallometric scaling with respect to body size. Specifically, the scaling exponent for the length–fecundity relationship was 3.24, which was greater than the scaling exponent of 3.05 for the length–body mass relationship. This indicates that large females possess a disproportionately greater reproductive capacity with respect to body mass than the equivalent biomass of smaller females.

Conclusion

Compared with previous studies spanning over a half-century, age at 50% maturity and fecundity were found to be relatively invariant, although variation found between contemporary studies may represent methodological and interpretive differences. Reproductive-related life history traits of female Atlantic Striped Bass are apparently robust to long-term decadal changes in fishing intensity, stock size, habitat alterations, and environmental conditions.