Validating the Stock Apportionment of Commercial Fisheries Landings Using Positional Data from Vessel Monitoring Systems (VMS)

摘要

Vessel Monitoring System (VMS) positional data from northeast United States fisheries were used to validate the statistical area fished and stock allocation of commercial landings derived from mandatory Vessel Trip Reports (VTR). A gear-specific speed algorithm was applied to 20042006 VMS data from the otter trawl, scallop dredge, sink gillnet, and benthic longline fisheries to estimate the location of fishing activity. Estimated fishing locations were used to allocate the landings of 8 federally managed species to stock areas: Atlantic cod (Gadus morhua), haddock (Melanogrammus aeglefinus), yellowtail flounder (Limanda ferruginea), winter flounder (Pseudopleuronectes americanus), windowpane flounder (Scophthalmus aquosus), goosefish (Lophius americanus), silver hake (Merluccius bilinearis), and red hake (Urophycis chuss). Haul location and catch data from the Northeast Fisheries Observer Program (NEFOP) were used to assess the relative accuracy of both VMS and VTR allocation methods. Overall, the mean VMS-NEFOP agreement rate was 86.4 - 7.6% compared to a mean VTRNEFOP agreement rate of 58.5 - 4.9%. The VMS algorithm had a tendency (approx. 10% of all trips) to overestimate the number of statistical areas fished; when all fishing activity from a given trip occurred in a single statistical area, VTRs more accurately reflected the true fishing location. However, on trips where fishing activity occurred in multiple statistical area, the VMS algorithm showed pronounced gains (77.2 - 11.2% NEFOP agreement) relative to VTR reports (12.0 - 5.9% NEFOP agreement). The VMS method achieved distributions of stock landings closer to NEFOP estimates in 18 out of 24 instances (8 species over 3 years). The stock allocations from both the VMS and VTR-based methods were within - 5% for all stocks, suggesting that the impacts on total stock allocations are relatively minor. However, these small differences represent major relative differences for less abundant stocks such as southern New England/mid-Atlantic yellowtail flounder. In 2005 the VTR-based method allocated 61.9% more yellowtail flounder landings relative to 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 where targeted outreach activities would improve the accuracy of VTR statistical area reporting.