Testing staining techniques to determine age and growth of Dasyatis pastinaca (Linnaeus, 1758) captured in Iskenderun Bay, northeastern Mediterranean

Abstract

This study tested the suitability of several staining methods to determine the age of common stingray (Dasyatis pastinaca) from Iskenderun Bay, Turkey. A total of 384 specimens (16.6 cm-69.3 cm disc width) were obtained by trawling between September 2010 and December 2011. Sex ratio of the samples was 53% males and 47% females. Appropriate age determination was firstly demonstrated using Safranin-O staining. Age readings were made by two independent readers and the index of average percent error (IAPE) determined as 6.3% for Safranin-O, 6.8% for Crystal Violet, 7.9% for Alcian Blue, and 9.3% for Silver Nitrate. Safranin-O and Crystal Violet staining methods provided the best results. Verification of temporal growth ring formation was by marginal increment analysis. Disc width-weight relationships were determined by W = 0.0272*DW3.06 for females and W = 0.0247*DW3.08 for males. Estimates of the von Bertalanffy growth parameters indicated a larger asymptotic disc width (DW infinity = 127.06 cm) for females than for males (DW infinity = 114.54 cm); growth parameters were k = 0.058 year(-1), t(o) = -1.508 and k = 0.041 year(-1), t(o) = -3.632 for females and males, respectively.