REPRODUCTIVE CONDITIONS OF THE ATLANTIC STURGEON (ACIPENSER OXYRINCHUS) IN THE HUDSON RIVER

Ninety-four prespawning adult Atlantic sturgeon (Acipenser oxyrindus) were sampled in the Hudson River for age, sex, body size, gonad weight , fecundity, mature oocyte size, and plasma concentrations of gonadotr opins, sex steroids, and vitellogenin during the spring spawning migra tions in 1992 and 1993. In males, the age and total length ranged from 12 yr to 19 yr and from 133 cm to 204 cm and in females from 14 yr to 36 yr and from 197 cm to 254 cm. The majority of males were 13-16 yr old, and females were 16-20 yr old. Some females had residual atretic ovarian bodies, presumably remaining from a previous spawning and indi cating iteroparity. Pre-ovulatory condition was recognized by migratio n of the germinal vesicle or by germinal vesicle breakdown and by sign ificantly elevated plasma gonadotropins, progesterone, and vitellogeni n. All pre-ovulatory females were captured upriver from Hudson River k ilometer 136. Individual fecundity ranged from 0.4 million to 2.0 mill ion eggs and oocyte diameter from 2.4 mm to 2.9 mm, and both character s exhibited a significant (p < 0.05) positive relationship with female body size. Iteroparous females, tentatively identified by the presenc e of atretic bodies remaining in the ovary from a previous spawning, h ad significantly (p < 0.05) higher fecundity and produced larger eggs, compared with females spawning presumably for the first time.