Apristurus microps

Abstract: Data from a scientific deep-water trawl fisheries survey in the north-east Atlantic were analysed to determine the spatial and bathymetric distribution of elasmobranch species and assess the change in relative abundance over the period 1998-2013. During this period, commercial fisheries for deep-water sharks went from being entirely unregulated, to being briefly managed, to being completely prohibited. A total of 22 species of shark and 10 species of skate were recorded between depths of 300 and 2030 m. All showed strong species-specific depth-related trends in abundance. Out of the 11 more common species, five showed no change in relative abundance over time, two (Centrophorus squamosus and Centroselachus crepidater) declined significantly and four increased in relative abundance (Apristurus aphyodes, Apristurus microps, Galeus melastomus and Deania calcea). Assuming these populations were depleted by fisheries in the past, the current data do not suggest there has been an overall recovery. Positive signs for some species in the most recent years suggest movement or recruitment back into the area; however, it is of concern that two species continued to decline. There is a continued need to have precautionary management of these elasmobranch species, and the current ban on landing these species in European waters remains appropriate.

Abstract: This study presents information on the reproductive biology of five southern African catshark species: Apristurus microps, A. saldanha, Apristurus sp., Galeus polli, and Scyliorhinus capensis. They were caught between Walvis Bay, Namibia, and Cape Agulhas, South Africa, from 50 to 1016 m deep. The reproductive mode of four species was oviparous, whereas G. polli exhibited aplacental viviparity. Males of all species attained first maturity slightly larger than females, and males of the four oviparous species attained a larger L Tmax than females. The length at 50% maturity was similar for males and females in most species. All species matured at an L T > 75% of L Tmax except for male Apristurus spp. and female G. polli, which matured at 71.2% and 68.8%, respectively, of L Tmax . The egg case of A. microps has minute tendrils, whereas those of S. capensis were quite long, suggesting different egg-laying habitats. Fecundity in G. polli ranged from 5 to 13, and litter size increased in relation to increased female length. Embryos of G. polli were large, each measuring approximately 30% of female L T . Neonates of G. polli were common and appear to have a demersal lifestyle; those of the four oviparous species were entirely absent from the study. Gravid A. microps were found in summer and winter, indicating a protracted breeding cycle, but reproductively active S. capensis were caught only in winter. Prior to this study, reproductive information on these catsharks was largely lacking.