As part of the "Impact on Marine Ecosystem" study, global artisanal fishery data has been generated by the National Center for Ecological Analysis and Synthesis and can be downloaded in a raster format here.
Of course there are the usual global dataset issues in terms of accuracy, completeness, etc. Here some background information on the creation of the artisanal fishing dataset from A Global Map of Human Impact on Marine Ecosystems by Benjamin S. Halpern et al., published in Science on the 15th of February 2008:
Data for these variables were obtained from the CIA World Factbook (http://www.cia.gov/cia/publications/factbook), World Resources Institute EarthTrends database (http://www.earthtrends.wri.org), and ETOPO2 bathymetric data (http://www.ngdc.noaa.gov/mgg/global/relief/ETOPO2/) and included: length of coastline, shallow shelf area (<100m> proportion of population livingwithin 100 km of the coast, per-capita GDP (calculated as the mean of this value from 2001-2003, in 2006 US dollars), unemployment rates, proportion of total protein supply from fish products, daily per capita consumption of fish and fisheries products, total number of commercial fishing vessels, total annual landings of marine animals taken for commercial, industrial, recreational and subsistence purposes, and the ratio of total landings to total number of commercial vessels.
