Evaluation of commercial logbook records: 1991-2013

There has been considerable interest during recent years in evaluating the directed commercial halibut fi shery catch-rates and comparing them with observations from the IPHC’s annual setline survey. Further, it has been more than a decade since there has been a review of the IPHC’s current method for standardizing annual fi shery logbook observations for use in the stock assessment (Clark 2002). The standard method excludes snap-gear logbook records in all regulatory areas except 2A and 2B (where the proportion of snap-gear usage is high), all autoline records, and all records with hook-spacing less than four feet (Stewart 2015). There were a number of questions during recent annual meetings regarding how many data were being ignored, whether the spatial distribution of the records excluded could be important, and how robust the results of the standard method might be relative to the catch-rates observed by the entire halibut fl eet. To address these concerns, in 2014 a detailed investigation of recent logbook records was initiated. This project had fi ve primary goals: 1) Determine what fraction of the recent directed commercial fi shing activity is represented in the IPHC’s logbook records, and then delineate these records into those used in recent fi shery catch-rate analyses, those that could potentially be used, and those that are not reliable due to mixed-species targeting or incomplete recording of the fi shing information. 2) Compare the fi shery catch-rates among fi xed-hook, snap-gear, and autoline by regulatory area and year. 3) Investigate the hook-spacing correction used to standardize logbook records, and explore whether it might be modelled directly rather than treated as a correction to the raw data. 4) Compare model-based estimates of recent catch-rate trends with standard calculations used in stock assessment analyses. 5) Create a framework that would allow this type of analysis to be periodically repeated, and potentially extended to make the best possible use of the valuable information contained in fi shery logbooks.