Estimating unaccounted fishing mortality in the Ross Sea and 88.2C–G bottom longline fisheries targeting Antarctic toothfish

Stock assessments rely upon estimates of the total mortality resulting from fishing activities. The level of mortality resulting from the loss of sections of bottom longline gear in the Ross Sea region and Subarea 88.2 Antarctic toothfish (Dissostichus mawsoni) fisheries is not currently known. Lost fishing gear should be monitored to provide information to evaluate how well CCAMLR meets its management objectives relating to human impacts on the Antarctic environment. We provide a method to estimate unaccounted fishing mortality from lost lines in the Ross Sea region and Subarea 88.2 Antarctic toothfish fisheries. Our estimates suggest that on average 175–244 t of Antarctic toothfish may be unaccounted annually. While these estimates may be improved through better data reporting practices, the current estimates have been provided as sensitivities in the 2011 stock assessments for the Ross Sea region and Subarea 88.2 fisheries.