Abstract:
This study examined the logbook record of the Oregon trawl fishery using a geographic information system (GIS) to determine the spatial and temporal distribution of English sole, Pleuronectes vetulus. The original logbook data for the years 1981,1982,1994,1995,1996 were filtered twice to provide both a general description of trends in the distribution of tows and catch parameters, and a more explicit ecological description of English sole catch dynamics. Tow distribution maps were used as a basis to evaluate the utility of the logbook data as a means to identify potential locations for harvest refugia. The spatial pattern of the trawl fishery changed dramatically between 1981-82 and 1994-96, although fishing activity was concentrated near ports of origin in all years. The fleet moved offshore and northward and the species composition of tows shifted from shallow water species toward deeper water fisheries. The English sole fishery remained distinct from the trawl fishery, although English sole tows and yields declined. High densities of English sole tows and the largest percentage annual English sole catch-per-unit-effort (CPUE) occurred in waters offshore Astoria, within 46 - 47°, in all years. Eight geographical regions were ranked according to their value to the production of English sole and their importance to the fishery. Sites of potential harvest refugia were selected based on their ability to contribute to the goal of long-term sustainability of the English sole fishery, by providing a buffer against errors in fishery management. Four sites were identified as potential locations, three sites in the offshore waters of the ports of Astoria, Newport and Brookings, and a fourth site in the nearshore zone along the Oregon coast, within the 50-fathom contour. The study concluded that logbook data will be useful to future planning of marine harvest refugia along the Pacific coast, because the data provide insights into fishing behavior and the relative amounts of fishing intensity that occur in different geographic regions. In addition, use of logbook data provide an opportunity for involvement of the fishing industry in the marine harvest refugia planning.
