Using a multi-parameter approach to reassess maturity of spiny dogfish, Squalus acanthias, following increased fishing pressure in the Western North Atlantic

Abstract

Age at size was linked to sexual maturity in 147 male and 249 female spiny dogfish, Squalus acanthias, from the Gulf of Maine using three criteria: (1) gross reproductive morphology, (2) histology and (3) steroid hormone concentrations. Collected specimens ranged from 25cm to 102cm stretch total length, and 0 to 24 years old. Maturity ogives for males, based on data gathered for clasper length, circulating testosterone concentrations and proportion of tissue with mature spermatocysts within the testes, predicted that 50% maturity occurred at a total length of 63.1mm and 7.5 years of age. For females, maturity ogives, based on data gathered for embryo presence, ovary mass, shell gland mass, follicle size and circulating estradiol concentrations, predicted that 50% maturity occurred at a total length of 76.9cm and 9.1 years of age. These maturity parameters for females decreased by over 7cm and 3 years from those previously reported two decades ago for S. acanthias in the Western North Atlantic. While the causes for the decrease in maturity parameters could not be determined, as this was beyond the scope of the current study, these changes occurred over a period of increased fishing pressure.