Evaluating the Impacts of the Ross Sea Region Marine Protected Area for Antarctic Toothfish (dissostichus Mawsoni) with a Spatially-Explicit Population Model

In 2016, the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) adopted what was then the world's largest marine protected area (MPA), the Ross Sea region marine protected area or “RSrMPA.” Only one fishery operates in the Ross Sea region (RSr). This fishery targets Antarctic toothfish (Dissostichus mawsoni), which has an ontogenically-segregated life-history spanning both the RSrMPA and areas fully open to fishing. Here, we present a spatially-explicit population model for RSr Antarctic toothfish, which we use to run projections to evaluate the impacts of the RSrMPA for the species. We considered six alternative scenarios, which consisted of the combination of two spatial management scenarios (MPA versus no-MPA situations) and three different spatial patterns of future fishing. The same CCAMLR decision rules were employed to determine a total catch limit in each case. Our results indicate that access to productive fishing grounds continues to exist with the RSrMPA, the total catch limit and fishery catch rates are not impacted, and the RSrMPA specific objectives relating to Antarctic toothfish are being met. The no-take fraction of the RSrMPA (the “General Protection Zones”) protects areas of ecological importance for the species (juvenile settlement areas, migration corridors for maturing individuals, and adult feeding areas), while the partial-take fraction of the MPA (the “Special Research Zone”) allows for the continuity and integrity of a critical tagging program. Our modelling framework provides valuable information to inform resource management at CCAMLR and could be employed to explore other proposed large-scale MPAs in the Southern Ocean.