Using Positional Data from Vessel Monitoring Systems to Validate the Logbook-Reported Area Fished and the Stock Allocation of Commercial Fisheries Landings

Abstract

Stock allocations derived from vessel monitoring system (VMS) positional data from northeastern U.S. fisheries were compared with those obtained from mandatory vessel trip report (VTR) logbooks. A gear-specific speed algorithm was applied to VMS positions collected in 2005 from otter trawl, Atlantic sea scallop Placopecten magellanicus dredge, sink gill-net, and benthic longline fisheries to estimate the locations of fishing activity. Estimated fishing locations were used to reallocate the stock area landings of eight federally managed groundfish species. The accuracy of the VMS method relative to that of the mandatory logbooks was assessed using haul locations and catch data recorded by at-sea observers. The VMS algorithm tended to overestimate the number of statistical areas fished, such that when a trip's fishing activity occurred in a single statistical area, logbooks more accurately reflected the true fishing location. However, when fishing activity occurred in multiple statistical areas, the VMS algorithm showed appreciable gains relative to logbook data. Compared with mandatory logbooks, the VMS method achieved distributions of stock landings closer to observer estimates in 77.8% of the cases examined. The stock allocation percentages from both the VMS- and VTR-based methods were within 1.7% for all stocks, suggesting that the impacts on total stock allocations are relatively minor. However, these small differences represent major relative differences in stock landings for less abundant stocks such as southern New England–Mid-Atlantic yellowtail flounder Limanda ferruginea, where the VTR-based method allocated 61.9% more landings than the VMS-based method. The VMS-based method is not a replacement for the VTR-based method; however, it can and should be used as a tool to identify those vessels for which targeted outreach activities would improve the accuracy of VTR statistical area reporting.