The efficacy of video-based electronic monitoring technology for at-sea monitoring of the halibut longline fishery

This project involved the large-scale deployment of electronic monitoring (EM) systems on the 2002 British Columbia halibut longline fishery to evaluate the feasibility of EM as an alternative to observer-based at-sea monitoring. EM systems were deployed on 59 regular halibut fishing trips involving 19 fishing vessels, providing about 700 usable sets, 1,000 hours of imagery, and 350,000 observed hooks. Catch items identified by EM represented over 60 fish, invertebrate or seabird species or species groupings, and the 15 fish most abundant species accounted for 98% of the catch. Data from fishing trips where EM and observers were deployed (about 55% of trips) were compared by total overall catch, total catch by set, and catch by individual hook. Overall EM and observer catch estimates agreed within 2%, and individual identifications by hook agreed in over 90% of the catch records. EM reliably (i.e., accuracy within 10%) distinguished thirteen species that represented 97% of the halibut fishery catch. Some species, particularly non-distinct forms, were not identified well by EM. Sample sizes were too small among half the species for determination of an EM species identification capability. Close agreement between EM and observer was also evident with species utilization determination (i.e., kept or discarded) and time, location and depth at set start and finish.
The results of this study demonstrated that EM is a promising tool for at-sea monitoring applications. EM and observer programs differ in many ways in terms of data collection capabilities and program design issues. While the utility of this new technology will depend upon the specific fishery monitoring objectives, the substantially lower cost and broader fleet suitability of EM over observers makes this an attractive option. The authors suggest that a combined EM-based monitoring for the halibut fishery should be continued using two approaches: an integrated EM-observer program using both methods in a complimentary fashion to achieve fleet sampling objectives; and using EM and an electronic fishing log as an at-sea monitoring audit tool. Fruther testing using combined EM and observers on the same trip should occur in the ZN fishery to improve EM rockfish identification capability. The authors also recommend that DFO more comprehensively define the at-sea monitoring objectives of the halibut fishery and strengthen their support for EM-based monitoring approaches to further the development of this technology.