Trend in bycatch in the tuna longline fishery in India with reference to the biology of dominant species of pelagic sharks

The bycatch contribute substantially to the longline catch in India. The exploratory tuna longline surveys conducted by Fishery Survey of India in the exclusive economic zone(EEZ) of India has indicated the abundance of these species. The study of the bycatch trend is utmost important so as to manage the tuna fishery effectively. In the present study along with the targeted catch i.e the tunas, 31 bycatch species i.e the bill fishes, pelagic sharks, rays, barracudas, dolphin fish, lancet fish etc. were recorded. The sharks dominate the bycatch groups in the Indian EEZ. The fishes caught by the four longliners i.e MFV Matsya Vrushti, MFV Matsya Drushti, MFV Yellow Fin and MFV Blue Marlin during 2010-19 were analyzed for finding out the distribution and abundance pattern of the tunas and the bycatch species. An aggregate hooking rate of 0.28%(number/100 hooks) and a catch rate of 33.6(kg/1000hooks) was recorded from the Indian EEZ. The dominant species of pelagic sharks occurring as bycatch were taken for in depth biological studies such as sex ratio, length frequency, length-weight, dietary analysis etc. This study will be useful for framing necessary guidelines for managing the tuna long line fisheries and to know more on the biology of the large pelagics.