Age, growth, longevity, natural mortality and maturity of the longnose spurdog, Squalus blainvillei (Chondrichthyes: Squalidae), in the Gulf of Gabes (Central Mediterranean Sea)

Abstract

Age, growth, longevity, natural mortality and size and age at maturity of the longnose spurdog, Squalus blainvillei, in the Gulf of Gabes (Tunisia, Central Mediterranean Sea) are reported. Marginal increment suggested annual band formation. Age estimates ranged from 3 to 15 and 4 to 19 years for males and females, respectively. Von Bertalanffy growth parameters derived from length at age data were: L-infinity = 105.7 cm, K = 0.11year(-1), t(0) = -1.12 year for females and L-infinity = 91.1 cm, K = 0.14 year(-1), t(0) = -1.42 year for males. Males and females reached maturity at 52.3 cm and 62.5 cm TL corresponding to 4.97 and 7.44 years, respectively. Longevity estimates were 24.75 and 31.50 years for males and females, respectively. Based on life history parameters, natural mortality estimation M ranged from 0.16 to 0.33.