Trends in the Alaskan bottom-trawl fishery from 1993-2015: a GIS-based spatiotemporal analysis

The Bering Sea, Aleutian Islands, and Gulf of Alaska yield one of the largest sustainable fishing industries in the world. To ensure continued sustainable practices, the effects of fishing activity on the health of the ecosystem should be actively studied. Bottom-trawl gear is a sustainability concern due to its direct interaction with the benthic layer. Impact from bottom-trawl fisheries is difficult to assess, particularly over the long-term. Using fishery-dependent observer data from National Marine Fisheries (NMFS) provides insight on the location and the intensity of fishing effort, which can identify areas most exposed to fishing pressure. ❧ In this study, the spatial and temporal extent of Alaskan bottom-trawl fishing effort in the Bering Sea, Aleutian Islands, and Gulf of Alaska was explored in a space-time cube in ArcGIS Pro v1.4.1 using NMFS data collected between 1993 and 2015. Various statistical techniques were used to examine spatiotemporal autocorrelation and clustering in this data. Results indicate that fishing effort was not randomly distributed over space and time and shows non-random clustering. This clustering is assessed using Moran’s I. A three-dimensional hot spot analysis shows which areas were most intensely fished and illustrates the long-term trends over the study period. The variables analyzed are number of hauls per area and total catch per area. The data was then compared with two external factors, sea ice concentration and closed marine protected areas, to determine the effect of changing regulations and climate on fishing activity. The analysis uses long-term retrospective data to examine changes in fishing effort over time in the Alaskan bottom-trawl fishery.