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.