Notes on the reproduction and otoliths of Neoscopelus cf. microchir (Myctophiformes: Neoscopelidae) in the Galicia Bank, NE Atlantic.

Abstract

ABSTRACT This study investigates the reproductive biology and otolith characteristics of Neoscopelus cf. microchir, based on 24 specimens collected in summer from the Galicia Bank, a seamount in the NE Atlantic. Specimens ranged in length from 20 to 34 cm and in gutted weight from 41 to 335 g. All gonads were dissected and histologically analysed. Sagitta otoliths were removed and measured. The northeast Atlantic N cf. microchir is an iteroparous batch spawner with asynchronous oocyte development, which shows spawning activity in summer. Length at maturity (L50) was estimated to be 23.5 cm for females. Otolith height ranged from 8.28–13.92 mm, and all otolith dimensions increased with fish length. A translucent zone, probably associated with the settlement, started 2.5 mm from the otolith’s nucleus and had a mean width of 0.34 mm. Parameters of the LT – WG relationship were a = 2.5e-06 and b = 3.2 for both sexes combined. The gonadosomatic index varied between 0.6 and 11.9%, differing significantly between maturity stages. This study provides new insights into the reproductive biology and otolith characteristics of N. cf. microchir which will be useful for future studies on the population dynamics and life history of this deep-sea fish species.