Download AEBR 355 Spatial risk assessment for selected shark species in New Zealand – Part II: trawl bycatch

This report describes application of a novel risk assessment approach to trawl bycatch (non-target) shark species. The assessment estimated the exploitation rate inflicted on each of twelve species by fishing in the New Zealand Exclusive Economic Zone. Although trawl catches predominated, all relevant fishing methods were included so that the total fisheries impact could be gauged. The exploitation rate is a measure of the proportion of the selected population biomass that is killed as a result of fishing, and includes those individuals that die even when returned to the ocean. The exploitation was compared to a theoretical productivity measure to estimate whether it was high enough to inflict long-term damage on the population. Elephantfish (Callorhinchus milii) and carpet shark (Cephaloscyllium isabellum) were identified as being at higher risk from fishing.