Spatial-temporal variation on Euphausia superba fishing ground in the northern Antarctic Peninsula based on point pattern model

As a key species in the Antarctic ecosystem, the spatial and temporal dynamics of Antarctic krill's fishing ground is becoming important issues for the role effects of krill's oceanic ecosystem function and resource management.Using multi-year Chinese krill fishery scientific data by month group,combining three spatial factors - longitude, latitude and offshore distance, the optimal point pattern model of monthly krill distribution and the variance analysis results were obtained for the krill fishery in the northern Antarctic Peninsula based on the spatial point pattern method, and the possible potential fishing grounds were predicted based on the proposed optimal point pattern model. The results were: (1) In December, the greatest distance of fishing grounds to shore (45 km) can be found. Subsequently, the fishing grounds were gradually approaching coastline of the South Shetland Islands. By March the fishing grounds were at the least distance to the Antarctic Peninsula shoreline. After March, fishing ground gradually retreated from the coastal area, in April and May distance of fishing grounds to shore maintained about 13 km. (2) The variance analysis of the optimal point pattern model indicated the explained rates of variance to the model in December, January, March and April were 59%, 60%, 57% and 68%, respectively. Spatial factors can fit the distribution of krill fishing ground very well in these months. But in February and May, the explained rate of the variance to spatial point pattern model reduced to 38% and 32%, respectively. (3) Fishing grounds were located in the northern King George Island during austral summer (December to January).In February, a secondary fishing ground was formed around the Livingston Island, and the third fishing ground occurred in the middle of the Bransfield Strait.During March-May fishing ground distributed along in the Bransfield Strait paralleled to the Antarctic Peninsula. In conclusion, the offshore distance of the fishing ground coincided with the extension and retreating of the sea ice boundary in the northern Antarctic Peninsula. The point pattern model of krill fishery based on spatial factors can well fit the temporal and spatial evolution of krill fishing ground in most months. Combined with the catch per fishing unit (CPUE), the point pattern model can be used as a potential technique to explore the hotspot of krill aggregation.