Reproductive Parameters of Female Long-finned Pilot Whales (Globicephala melas edwardii) from the Southwestern Atlantic

SOTO, FLORENCIA ANABELLA; GRANDI, MARÍA FLORENCIA; GARCÍA, NÉSTOR ANIBAL; CRESPO, ENRIQUE ALBERTO; DANS, SILVANA LAURA

ZOOLOGICAL STUDIES

ACAD SINICA INST ZOOLOGY

Lugar: Taiwan; Año: 2017 vol. 56 p. 1 - 12

1021-5506

Mass strandings represent a valuable source of information, especially when it comes to difficult-to-access pelagic species, such as Globicephala melas edwardii. We collected reproductive organs from 27 female pilot whales stranded in Caleta Malaspina, Chubut, Argentina. Our main objective was toanalyze reproductive parameters of female long-finned pilot whales in the southern hemisphere. To achieve this,we studied age and reproductive status in order to approximate age and body length at sexual maturity, breeding interval, and fertility of this subspecies. The maturity state was determined by recording different ovulation bodies obtained from histological sections and by assessing the presence of milk in the mammary glands anda fetus, and we concluded that 5 of the females were immature and 22 were mature females. Finding maturefemales in different reproductive states (resting, in lactation, pregnant, or pregnant and in lactation) along withthe great variety of fetus sizes would indicate that copulation and birth are not governed by seasonality. Age atsexual maturity was 8 years old and length at sexual maturity would reach 365.50 cm. The annual pregnancyrate was constant with age for mature females at 0.41 ovul / year, with a breeding interval of 2.4 years. The average fertility varied between 0.19 and 0.21. All the parameters are within the estimated range for females ofthe North Atlantic subpopulation, except for the breeding interval, which was significantly lower than estimatesfor the northern subspecies. This study could be limited because all individuals come from a single mass stranding. While this study allowed us to reach some conclusions about the reproductive biology of female G.melas edwardii in the Southwestern Atlantic Ocean, further studies are needed to fully comprehend the behaviorand biology of this species.