Population biology and ageing of the deep water sharks Galeus melastomus, Centroselachus crepidater and Apristurus aphyodes from the Rockall Trough, north-east Atlantic

• Published in: Journal of the Marine Biological Association of the United Kingdom
• Main Authors: Moore, D.M., Neat, F.C., McCarthy, I.D.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 2013
• Subjects: Aquatic Science; Rockall Trough; North East Atlantic
• Online Access: http://dx.doi.org/10.1017/s0025315413000374; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0025315413000374

This study presents new information on the population biology, growth and maturation schedules of Galeus melastomus, Centroselachus crepidater and Apristurus aphyodes sampled from the Rockall Trough, a region where deep sea fishing activity has been prevalent for the past 40 years and where shark by-catch is considerable. Both G. melastomus and C. crepidater showed significant sexual size dimorphism with females attaining a greater length and mass. The size (L 50 ) at first maturity was estimated to be 55.6 cm total length (TL) for males and 59.7 cm TL for females in G. melastomus , 57.2 cm TL for males and 75.4 cm TL for females in C. crepidater and 49.0 cm TL for males and 56.9 cm TL for females in A. aphyodes . This represents the first TL 50 analysis for Apristurus aphyodes globally. Sharks were aged using a technique which employed cobalt (II) nitrate to stain growth bands in vertebra centra. Band pairs were successfully viewed in G. melastomus and pair counts ranged from 0 to 5 in males and 2 to 7 in females. A higher asymptotic length was deduced from the von Bertalanffy growth equation for females than males (females: L ∞ = 69.3 cm; males: L ∞ = 60.8 cm) in G. melastomus . Staining was unsuccessful in C. crepidater and A. aphyodes and age could not be determined using this technique.