ABSTRACT
The reproductive cycle of Raja texana was determined from 63 females (510-630 mm total length, L(T)) and 81 males (355-546 mm L(T)) collected from the Gulf of Mexico. The results, based on follicle size, mature spermatocysts and gonadosomatic index (I(G)) suggests year-round reproductive activity.
Subject(s)
Reproduction , Skates, Fish/physiology , Animals , Body Size , Female , Male , Ovarian Follicle/physiology , Sexual Maturation , Spermatocytes/physiologyABSTRACT
Age and size at sexual maturity was determined for 185 male and 96 female smooth skates Malacoraja senta (ranging in size from 370 to 680 mm total length L(T)), collected from the western Gulf of Maine. Maturity ogives for males, based on clasper length, testis mass and the proportion of mature spermatocysts in the testes, suggest that 50% maturity occurs between 9 and 10 years and 560 mm L(T). Maturity ogives for females, based on ovary mass, shell-gland mass and maximum follicle size, suggest that 50% maturity occurs at age 9 years and 540 mm L(T).
Subject(s)
Body Size , Sexual Maturation , Skates, Fish/physiology , Aging , Animals , Female , Maine , Male , Ovary/growth & development , Testis/growth & developmentABSTRACT
Size and age estimates at sexual maturity were determined for 162 male and 273 female little skates Leucoraja erinacea collected from the western Gulf of Maine. Maturity ogives suggest that 50% maturity in females occurs at age 9.5 years and 480 mm total length (LT), whereas 50% maturity in males occurs at a slightly younger age of 7.7 years and smaller size of 460 mm LT. Age estimates were made from 389 L. erinacea ranging in size from 93 to 570 mm LT. The index of average per cent error and age-bias plots indicated that the ageing methods were precise and non-biased. Additionally, annual periodicity of band formation was validated with oxytetracycline in eight individuals (three males and five females) ranging in age from 3 to 12 years. In conclusion, results from this study indicate that L. erinacea exhibits characteristics that make other elasmobranch populations highly susceptible to overexploitation.
