Methodology for automated spatial sea ice summaries in the Southern Ocean

Sea ice is recognised as a core driver of both ecosystem dynamics and fishery performance in the Southern Ocean. Sea ice can limit access to fishing grounds, for both commercial fishing and scientific research. Although satellite data are available and have been used for ecosystem monitoring purposes and to inform research plans by CCAMLR, no quantitative summaries relative to fishing access are in use by CCAMLR. We develop a method to spatially and temporally summarise satellite-derived sea ice concentration data in the Southern Ocean, and relate it to data on commercial fishing vessel operations around the Antarctic continental margin. A spatial view is used to characterise the spatial dynamics of sea ice in a target location for a specified period, and a temporal view is used to characterise the inter-annual patterns within a target area. Both can be viewed relative to ice conditions during historical fishing events. The distribution of local ice concentration at the time of each fishing event relative to the weighted ice concentrations within the fishery footprint was used to develop the relationship between sea ice concentration and fishing. Although more than 85% of fishing events occurred in areas with less than 20% sea ice, a threshold of 40–60% sea ice indicated the transition from fished to non-fished conditions. We present a summary of conditions in SSRUs 88.2C-G as a case study to identify and characterise areas with reliable access for the collection of fishery data.