Preliminary Observations on the Reproductive Cycle and Uterine Fecundity of the Yellow Stingray, Urobatis jamaicensis (Elasmobranchii: Mylioba tiformes: Urolophidae) in Southeast Florida, U.S.A.

The yellow stingray, Urobatis jamaicensis is the most common elasmobranch observed among the coral reefs and associated habitats of Southeast Florida, U.S.A. In coastal waters off Broward County, Florida, gravid females were observed throughout the year. Urobatis jamaicensis is an aplacental viviparous species with evidence of a short gestation period (five to six months). Vitellogenesis occurs concurrently with gestation, with the females having both term fetuses and mature ova simultaneously. It is likely that the females have a bi-annual reproductive cycle where each female is capable of producing two broods annually. The ovulation period in the spring/summer reproductive cycle ranged from January to April (peaks in late February/early March) and parturition occurred between June to September (peaks in late July/early August). The autumn/winter reproductive cycle overlaps with the spring/summer cycle, with ovulation ranging between August to September and parturition from November to January. Two functional uteri were observed with a maximum uterine fecundity of seven young. Brood size increased with maternal size and was significantly higher during the spring/summer cycle (x̄ = 3.1 ± 0.179 SEM, range 1-7) in comparison to the autumn/winter cycle (x̄ = 1.4 ± 0.110 SEM, range 1-3). Preliminary wet weight determinations indicated that U. jamaicensis is highly matrotropic with an approximate 4,600% increase in weight from mature ova to term fetuses.