Catch composition, reproductive biology and diet of the bramble shark Echinorhinus brucus (Squaliformes: Echinorhinidae) from the south‐eastern Arabian Sea

Abstract

Fishery and biological data are presented for the poorly known bramble shark Echinorhinus brucus (Squaliformes: Echinorhinidae), from the deep waters of the south-eastern Arabian Sea. A total of 5318 individuals from by-catch landings of deep-water bottom set longlines, gillnets and shrimp trawl fisheries operating at depths of 200-1200 m were recorded between January 2008 and December 2011 at the Kochi Fisheries Harbour (Kerala). A total of 431 individuals, from 46 to 318 cm total length (L(T)) and 0·8 to 132 kg total mass (M(T)), were examined to determine biological data for this species. The LT at which 50% were mature (L(T)50) for females and males was estimated at 189 and 187 cm LT. Litter size ranged from 10 to 36 and size at birth was between 42 and 46 cm L(T). Dietary analysis of stomach contents revealed E. brucus feeds on a variety of prey including crustaceans (69% index of relative importance, I(RI)), teleosts (25·8% I(RI)), cephalopods (1·7% I(RI)) and elasmobranchs (0·7% I(RI)). This study provides the first detailed biological data for this species and also highlights the extent of the by-catch fishery for this species in Indian waters.

Deep-Water Sharks, Rays, and Chimaeras of Brazil

“…The Brazilian deep-water elasmobranch diversity is poorly known and the recent increase in species records and descriptions are evidences of a possible unevaluated richness along the continental slope [17,31,35,36,75]. Large species such as M. owstoni, P. microdon, S. antarcticus, and C. granulosus were only reported when scientific efforts in search of deep-water resources were recently developed (PROARRASTO and REVIZEE programs) [27,37,38,61,83].…”

“…The number of reported species drastically increased from 119 to 176 along the past decade (Figure 1), which corresponds to a total number increase of 36%, or 63% in numeric terms of skates and rays and 16% of sharks [17,18,36]. This recent biological diversity boom is certainly related to the REVIZEE scientific surveys in the recent past (1996-2007) and its ongoing influence, which resulted in the most extensive effort in order to evaluate possible promising marine fishery resources in Brazil [52,75,122]. However, even these scientific surveys need to be properly designed to catch and better evaluate the elasmobranch biodiversity.…”

“…The deep-water gill net monitoring program for the monkfish fishery reported an estimation of 4378 specimens captured in 2001 with a CPUE of 0.55 specimens per 100 nets [15]. These bycatch levels bring concern on the conservation status of local populations of the bramble shark since there is restricted biological information on this species [75].…”

“…However, Guallart et al [79] considered this species particularly vulnerable to fisheries based on its low fecundity rates, long gestation periods, and late maturity. (Figure 4) being more abundant off the northeast coast, while E. lucifer was more abundantly recorded off the south/southeast coast [47,58,61,70,75,82]. However, these differences probably resulted from different fishing gears (bottom longline vs. otter trawl).…”

“…Other rare deep-water species were recorded along the Brazilian coast, but most of them are known by single records or sporadic captures, e.g., S. [15,30,36,37,58,61,75,85,[107][108][109][110]. These species probably are distributed in deeper waters and are currently inaccessible to the Brazilian deep-water fishery.…”