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- Techniques for enhancing vertebral bands in age estimation of California elasmobranchs
- Vertebrae from 1,152 elasmobranchs representing 22 species were collected between 1979 and 1981 to assess methods of enhancing incremental growth bands for age estimation. Thus far, we have tested methods previouslyreported in the literature, and have developed new procedures to enhance growth increments on 684 individuals of 14 species of elasmobranchs. Silver nitrate impregnation, X-radiograpby, and cedarwood oil clearing were the most successful techniques. Less effeetive were alizarin red staining, paraffin impregnation, alcohol immersiorn, and formic acid etching. Methods for preparing vertebrae and enhancing and counting growth increments are presented, and the problems associated with interpreting tile annual nature of such counts are discussed.
- Cailliet, Martin, Kusher, Wolf, Welden, Prince, Pulos
- Validated age and growth of the leopard shark, Triakis semifasciata, with comments on reproduction,
- The age, growth, and sexual maturation of the leopard shark, Triakis semifasciata, from central California were studied. Growth band counts in vertebral centra of 162 leopard sharks produced von Bertalanffy growth curves with L ∞, K. and t o parameters of 1536 mm. 0.082, and -2.31, respectively, for both sexes combined. The L 8 value for females (1602 mm TL) was slightly but insignificantly higher than for males (1499 mm TL), but the K and t o values were almost identical. Seasonal changes in size modes of young-of-the-year leopard sharks, centrum edge characteristics, and growth and tetracycline mark-recapture from the field were used to validate annual deposition of vertebral centrum band pairs. Sexual maturity was evaluated by the gonads and presence of sperm and eggs; males mature at 7 yr and at about 63% of asymptotic length, and females mature at 10 yr, and at about 72% of asymptotic length. This slow growth, late maturity, and relatively low fecundity may increase their susceptibility to over-exploitation. © 1992 Kluwer Academic Publishers., Cited By (since 1996):53, Fish and Fisheries, CODEN: EBFID, ,
- Kusher, Smith, Cailliet