Idade e crescimento do tubarão-martelo-entalhado, Sphyrna lewini (Griffith and Smith, 1834), da costa sul do Brasil

Submitted by Paula Gautério (paulaporto_g@hotmail.com) on 2014-01-21T19:17:02Z No. of bitstreams: 1 Age and growth of the scalloped hammerhead shark, Sphyrna lewini (Griffith and Smith, 1834), from the southern Brazilian coast.pdf: 380625 bytes, checksum: e651064e344c45b51239b178e8978ac6 (MD5)Approved for entry into archive by cristiane soares (krikasoares@live.com) on 2014-01-23T16:49:57Z (GMT) No. of bitstreams: 1 Age and growth of the scalloped hammerhead shark, Sphyrna lewini (Griffith and Smith, 1834), from the southern Brazilian coast.pdf: 380625 bytes, checksum: e651064e344c45b51239b178e8978ac6 (MD5)Made available in DSpace on 2014-01-23T16:49:57Z (GMT). No. of bitstreams: 1 Age and growth of the scalloped hammerhead shark, Sphyrna lewini (Griffith and Smith, 1834), from the southern Brazilian coast.pdf: 380625 bytes, checksum: e651064e344c45b51239b178e8978ac6 (MD5) Previous issue date: 2011Age and growth studies for the scalloped hammerhead shark, Sphyrna lewini (Griffith and Smith, 1834) caught along the southern Brazilian coast, were based on ring measurements of vertebrae sections of 115 males, 116 females and 14 unknown sexed sharks between 48 and 344 cm total length (TL). The von Bertalanffy growth models were best fit using back-calculated data. The growth parameters obtained for males, were L∞ = 266 cm; K = 0.05/year; L0 = 47 cm. For females, L∞ = 300 cm; K = 0.05/year; L0 = 51 cm. An adult female reached 217 cm TL and was 31.5 years old. On the other hand, an adult male was 29.5 years old and measured 234 cm TL. Longevity estimate for males and females was 55 years. Therefore, S. lewini is a long-lived fish. Ageing precision, based on the IAPE index, was 5.6%. Marginal Increment analysis based on MIR index from hammerheads smaller than 105 cm, compared with the percentual of opaque and hyaline bands found per month ageing whole vertebrae, showed an annual ring formation, i.e., in winter.O estudo da idade e do crescimento do tubarão-martelo-entalhado, Sphyrna lewini (Griffith and Smith, 1834), na costa sul do Brasil, baseou-se na leitura de anéis em seções de vértebras de 115 machos, 116 fêmeas e de 14 exemplares com sexo indeterminado, com comprimentos totais (CT) entre 48 e 344 cm. Modelos de crescimento de von Bertalanffy foram mais bem ajustados aos dados de idade e comprimento retrocalculados, considerando sexos em separado. Os parâmetros de crescimento obtidos para os machos foram L∞ = 266 cm; K = 0,05/ano; L0 = 47 cm. Para as fêmeas L∞ = 300 cm; K = 0,05/ano; L0 = 51 cm. Uma fêmea adulta atingiu um CT de 217 cm e uma idade de 31,5 anos. Por sua vez, um macho adulto tinha 29,5 anos e CT de 234 cm. A estimativa de longevidade para machos e fêmeas foi de 55 anos. O índice de erro percentual médio (IAPE), que avalia a precisão na leitura de idades, foi de 5,6%. A análise do incremento marginal baseada no índice MIR e aplicada em tubarões com CT < 105 cm, comparada com o percentual de bandas opacas e hialinas mensais, obtido através de leituras de vértebras inteiras, indicou um padrão anual na formação dos anéis, ou seja, anéis de inverno