INVESTIGADORES
LUCIFORA Luis Omar
artículos
Título:
Reproductive biology of the school shark, Galeorhinus galeus, off Argentina: support for a single Southwestern Atlantic population with synchronized migratory movements
Autor/es:
LUIS O. LUCIFORA; ROBERTO C. MENNI; ALICIA H. ESCALANTE
Revista:
ENVIRONMENTAL BIOLOGY OF FISHES
Editorial:
Kluwer Academic Publishers
Referencias:
Año: 2004 vol. 71 p. 199 - 209
ISSN:
0378-1909
Resumen:
We sampled school sharks, Galeorhinus galeus, in Anegada Bay, Argentina, to investigate reproductive
ecology. Males dominated the catches in October and April, while females were more abundant than males
from November to March. Males were estimated to mature at a smaller size (108119 cm total length) than
females (mean 125 mm total length). Differences between fecundity and fertility were not dependent on
mother size. The largest embryos were found in late October and November, coinciding with ovulation.
This indicates that gestation lasts about 12 months. Embryonic growth was best described by a Gompertz
model. Four groups of females were recognized: (1) juveniles up to 129 cm TL, with translucent-to-white
ovarian follicles; (2) mature, non-pregnant, pre-ovulatory females with yellow ovarian follicles and low
gonadosomatic index (GSI); (3) mature non-pregnant ovulating females with large yellow ovarian follicles,
high GSI; and (4) pregnant females carrying near term embryos, with minute ovarian follicles. These
observations support a 3-year female reproductive cycle. The patterns of occurrence, reproductive condi-
tion, and embryonic growth of school sharks in northern Argentina are complementary to those from
southern Brazil, supporting the hypothesis that there is a single large population of school sharks in the
south western Atlantic.