Age and growth of the highly exploited narrownose smoothhound shark Mustelus schmitti (Springer, 1939) (Pisces: Elasmobranchii)

JUAN MANUEL MOLINA; GABRIELA ELIZABETH BLASINA; ANDREA LOPEZ CAZORLA

FISHERY BULLETIN

NATL MARINE FISHERIES SERVICE SCIENTIFIC PUBL OFFICE

Lugar: US; Año: 2017 vol. 115 p. 365 - 379

0090-0656

The narrownosesmoothhound(Mustelusschmitti)is the most exploited elasmobranch of Argentina,Brazil, and Uruguay, and is currently considered endangered by theInternational Union for Conservation of Nature. Providing information on age and growth can improve the conservation efforts made for this species. Therefore, our objective was to provide accurate and robust estimations of age structure and growth parameters for M. schmitti from Anegada Bay, an important shark nursery area in Argentina.Vertebrae of M. schmitti showed a pattern of alternating opaque and translucent bands with a yearly periodicity in band formation. Age determined from vertebral band counts ranged from 0 to 11 years. Calculated longevity and total natural mortality rates were20.87 and 0.19/year, and 12.24 and 0.26/year for females and males, respectively. This species reaches a length of approximately 400mm TL in the initial year of growth, and the age at first maturity at 7.61 years for females and 6.79 years for males. The slow growth and late age at maturity of the smoothhound indicates the need to implement additional conservation measures that encompass the three countries in which it is distributed, and should be aimed at achieving population recuperation and a sustainable fishery.