The smooth skate (Malacoraja senta) is a small species of skate that is native to the waters of the north-western Atlantic. Recent assessments in the Gulf of Maine indicate that the biomass of smooth skates has declined below threshold levels mandated by the Sustainable Fisheries Act. This decline, coupled with the paucity of biological data, has prompted the National Marine Fisheries Service to prohibit the possession of smooth skates in this region. Consequently, crucial life history information is now being collected, which could be used in the formulation of a management plan. The present study describes and characterises the reproductive cycle of female and male smooth skates, based on monthly samples taken off the coast of New Hampshire, USA, from May 2001 to April 2002. Gonadosomatic index (GSI), hepatosomatic index (HSI), shell gland weight, follicle size and egg case formation were assessed for 79 female skates. In general, these reproductive parameters remained relatively constant throughout most of the year. Additionally, the size distribution of ovarian follicles in females captured each month did not vary significantly. For males (n = 81), histological stages of spermatogenesis III to VI (SIII-SVI), GSI and HSI were examined. No significant differences were detected in male reproductive parameters, and production and maintenance of mature spermatocysts within the testes were observed throughout the year. Collectively, these findings indicate that, like other north Atlantic skate species, the smooth skate is reproductively active year-round.
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics
- Aquatic Science