Species composition of elasmobranchs in the surface and subsurface gillnet operation in the Northern Arabian Sea

Sharks form important part of bycatch of the tuna gillnet operations in Pakistan. WWF-Pakistan introduced subsurface gillnetting in 2014 in which gillnet are placed 1.4 to 2 m below the sea surface. Fishing fleet engaged in tuna gillnetting adopted subsurface gillnetting and by January 2016 entire tuna fleet was converted in subsurface gillnetting. Catch of  endangered, threatened and protected (ETP) species such as dolphins and sea turtles were observed to be much lower in subsurface gillnet as compared to surface operations. Sharks are among the other ETP species whose catches were dropped in subsurface gillnet as compared to surface operations. . It was observed that overall shark catches were 15.06 % lower in the subsurface gillnet operation as compared to surface placement of gillnets. A marked seasonality was observed in case of  dominating species including mako and silky shark. Catches of mako sharks was observed to be about 8.65 % higher in subsurface gillnets as compared  to surface gillnets.