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).

ELISIO, M; COLONELLO, J. H.; AWRUCH C. A.; SOMOZA, G. M.; MACCHI, G. J.

Congreso; American Elasmobranch Society Conference; 2017

As chondrichthyans have a relatively low reproductivepotential, intensive protection of their reproductive events is critical forits sustainable management. This study assessed the inter-annual changes inreproductive events of a commercially important shark in southern Brazil,Uruguay and Argentina, Mustelus schmitti, in relation to environmentalvariability in two coastal areas of the south-western Atlantic Ocean (El Rincónand Río de La Plata). Data were collected from 612 sample sites during six springsurveys. The reproductive scenarios were defined by the presence ofvitellogenic and ovulated females. Plasma sex steroids levels were assessed infemales at similar reproductive stage captured at different temperatures togather physiological evidences of reproductive thermal influences. Progressionof reproduction (increase in proportion of ovulated females) showed significantinter-annual variability associated with bottom temperature conditions. Sitesassociated with reproductive aggregations (co-occurrence of ovulated andvitellogenic females) were significantly warmer than those where onlyvitellogenic females were found. Depth and salinity were not related withovulation.