After release, sperm in round stingrays may then be stored in the
vas deferens for up to three months prior to mating (Babel, 1967).
While sperm storage was not directly examined in the present study,
sperm storage in male elasmobranchs is common (Pratt and Tanaka,
1994), although the exact site of storage may vary between species.
The production and storage of sperm in advance may allow males to
mate as soon as environmental conditions are conducive and females
are present. Babel (1967) found male round stingrays store sperm in
the vas deferens prior to copulation, similar to male Atlantic stingrays
(Piercy et al., 2003). In the present study, males sampled prior to the
breeding season had large quantities of sperm packets suspended in
seminal fluid in the vas deferens. Male round stingrays collected from
Seal Beach, California, from September through March released milt
when euthanized, although it is not known if sperm was released with
the ejaculate. After the breeding season, vas deferens diameters
appeared smaller and did not contain sperm packets, although these
were not measured, thus further quantitative examination into the
timing and extent of sperm storage in round stingrays is necessary.