Growth and Age Estimation of the Atlantic Sharpnose Shark, Rhizoprionodon terraenovae: A Comparison of Techniques

an adaptation of the Petersen distribution method, growth rates of Age Group 0 individuals are estimated to be most rapid during the three months following the June peak in parturition (mean growth rate = ca 5.0 cm/month), and slow during the winter and spring (mean growth rate from mid-September to midApril = 0.9 cm/month). Atlantic sharpnose were found to enter Age Group 1 at about 60 to 65 cm total length. The Age Group 1 growth rate is estimated to be a linear increase of about 1.3 cm/month throughout the year. By a simple graphic extrapolation, males were estimated to mature at 2.0 to 2.4 years (80 to 85 cm total length) and females at 2.4 to 2.8 years (85 to 90 cm total length). 2) The Ford-Walford method of applying the von Bertalanffy growth equation was used to describe growth data obtained via Parsons' (1983) vertebral ring age estimates. The equation was then used to estimate age at maturity for male R. terraenovae (2.4 to 3.5 years). An Age Group 1 growth rate of 1.0 cm/month and a much slower adult growth rate of 1.7 cm/year were estimated from vertebral ring data. 3) For purpose of comparison ages at maturity were calculated using Holden's (1974) modified von Bertalanffy growth equation (2.4 to 3.4 years for males and 2.8 to 3.9 years for females).