INVESTIGADORES
SOMOZA Gustavo Manuel
congresos y reuniones científicas
Título:
Inter-annual Changes in the Narrownose Smooth-hound Shark (Mustelus schmitti) reproductive timing in Relation to Temperature Patterns in Coastal Waters of the South-western Atlantic Ocean (34-42 °S)
Autor/es:
MARIANO ELISIO; JORGE COLONELLO; CYNTHIA AWRUCH; GUSTAVO M. SOMOZA; GUSTAVO J. MACCHI
Lugar:
Austin
Reunión:
Congreso; The Joing Meeting of Ichthyologists and Herpetologists; 2017
Institución organizadora:
American Society of Ichthyologists and Herpetologists
Resumen:
As chondrichthyans have a relatively low reproductive potential, intensive protection of their reproductive events is critical for its sustainable management. This study assessed the inter-annual changes in reproductive events of a commercially important shark in southern Brazil, Uruguay and Argentina, Mustelus schmitti, in relation to environmental variability in two coastal areas of the south-western Atlantic Ocean (El Rincón and Río de La Plata). Data were collected from 612 sample sites during six spring surveys. The reproductive scenarios were defined by the presence of vitellogenic and ovulated females. Plasma sex steroids levels were assessed in females at similar reproductivestage captured at different temperatures to gather physiological evidences ofreproductive thermal influences. Progression of reproduction (increase in proportion of ovulated females) showed significant inter-annual variability associated with bottom temperature conditions. Sites associated with reproductive aggregations (co-occurrence of ovulated and vitellogenic females) were significantly warmer than those where only vitellogenic females were found. Depth and salinity were not related with ovulation. The mean ovulation temperature estimated (temperature encompassing 50% of ovulated females) was 17.8 ± 0.98 °C. Change in sex steroid levels was consistent with theovulation temperature. Inter-annual differences of more than one month were predicted in the reproductive timing of M. schmitti by using historical bottom temperature variability models together with the estimated ovulation temperature. In sum, this study showed significant inter-annual changes in M. schmitti reproductive timing in response to thermal variability. Thus, present results should be considered for management strategies seeking reproductive protection of this species.