Life history of a wide‐ranging deepwater lantern shark in the north‐east Atlantic, Etmopterus spinax (Chondrichthyes: Etmopteridae), with implications for conservation

Abstract

In this paper, the population biology of the velvet belly lanternshark Etmopterus spinax was studied and life‐history coefficients determined. Age was estimated from sections of the second dorsal spine and validated by marginal increment analysis. Males attained a maximum age of 8 years while 11 year‐old females were found. Several growth models were fitted and compared for both size‐at‐age and mass‐at‐age data, showing that even though this is a small‐sized species, it has a relatively slow growth rate. This species matures late, specifically at 49·6 and 42·5% of the maximum observed ages for males and females, respectively. It has a low fecundity, with a mean ovarian fecundity of 9·94 oocytes and a mean uterine fecundity of 7·59 embryos per reproductive cycle. This species seems to have a long reproductive cycle, and even though no conclusive data were obtained, a 2–3 year cycle is possible. The estimated coefficients indicate that this species has a vulnerable life cycle, typical of deepwater squalid sharks. Given the high fishing pressures that it is suffering in the north‐east Atlantic, this fish may already be facing severe declines or in risk of facing them in the near future.