Proposal for a winter longline survey of Antarctic toothfish in Subarea 88.1 SSRUs B–C in 2016

We propose to conduct a scientific survey during the austral winter in the northern Ross Sea region to investigate spawning dynamics of Antarctic toothfish, as requested by the Scientific Committee in 2013. The longline survey is designed to cover key gaps in the knowledge of the life cycle of Antarctic toothfish (Dissostichus mawsoni) in the Ross Sea by collecting biological samples from a range of locations in Subarea 88.1 SSRUs B–C and begin in June 2016. The survey has two primary objectives, which are to investigate the spawning timing and locations of Antarctic toothfish in the northern Ross Sea region; and to investigate the maturity status, gonadosomatic index, histological characteristics, and condition of Antarctic toothfish during winter to further refine the developmental cycle. Other secondary objectives are to investigate the potential dispersion of eggs and larvae by studying the characteristics of Antarctic toothfish eggs with regards to buoyancy and to investigate the timing of the movement of Antarctic toothfish to and from the spawning grounds through an analysis of length and age composition of the catch, sex ratio, fish condition, and stable isotopes.