Evaluation of Video Technology for Monitoring of Multispecies Longline Catches

Abstract

At-sea catch monitoring of the Alaskan longline fishery for Pacific halibut Hippoglossus stenolepis is insufficient. The International Pacific Halibut Commission (IPHC) conducted studies in 2002 and 2004 comparing catch composition data from electronic monitoring (EM) systems to those of at-sea observers. The EM systems use automated data loggers linked to digital video cameras, a transducer on shipboard hydraulic systems, and a global positioning system receiver. The goal of both studies was to determine whether EM technologies could provide precise and verifiable catch composition data on commercial longline vessels to supplement and complement the data collected by fisheries observers. The EM video analyst's catch data were similar to the observers' data in the 2002 study; however, the video analyst recorded fewer fish for 7 of the 17 species categories investigated. In 2004, the IPHC employed EM technology in another study incorporating recommendations from the 2002 study, including improved camera configurations. The video analyst's data showed increased agreement with the observer data. However, the observers recorded slightly fewer individuals of some species categories, opposite the findings of the 2002 study. This change suggests that incorporating the technology recommendations enhanced the video analyst's accuracy relative to the observer data. Our analysis also highlights the fact that data provided by human observers have their own suite of errors and that the comparisons between EM and observers have no absolute standard of reference. The findings indicate that EM technology can effectively address the lack of catch composition data in the Pacific halibut and other hook-and-line fisheries in Alaska.