Age, Growth and Reproduction of the Thornback ray, Raja clavata (Linnaeus, 1758) in the Waters Off Gökçeada (the Northern Aegean Sea)

Abstract

In this study, the age, growth, maturity, and reproductive biology parameters of 262 Raja clavata, which were collected monthly from commercial trawlers off Gökçeada between February 2019 and February 2020, were estimated. The individuals comprise of 55.7% females and 44.3% males. The length of the females ranged between 23-84.2 cm (Disc width: 13.5-55.8 cm) and 11.2-74 cm (Disc width: 8-48.9 cm) for males. For age determination, age readings were performed on the vertebrae of 255 Raja clavata specimens (43.5% female, 56.4% male). The calculated von Bertalanffy growth parameters were estimated to be L∞= 93.04 cm, K=0.17 years-1, to=0.48 years for males, and L∞=102.46 cm, K=0.16 years-1, t0 =0.72 years for females. The minimum and maximum ages of the thornback rays ranged from 1 to 10 years. The first sexual maturity length of the population was measured to be L50 =57.7 cm in males, and L50 =66.1 cm in females.