Enhanced data collection in the Canadian Arctic for seabird bycatch information yields highly variable results

Incidental catch of seabirds (bycatch) in fisheries has been identified as a major threat to the conservation of seabird populations. Acquiring accurate, detailed data on seabird bycatch is an ongoing challenge to effective integrated ecosystem management of commercial fisheries. To collect detailed data on seabird bycatch in the Greenland halibut ( Reinhardtius hippoglossoides Walbaum, 1792) fishery in northern Canada, we applied two voluntary effort methods with industry partners that asked for additional, detailed information about the nature of the interactions between seabirds and the fishing gear than the data standardly reported in the fishery. We found that the amount of bird bycatch reported in both enhanced datasheets completed by at-sea observers (ASOs) and carcass collections yielded different results when compared to the typical seabird bycatch reporting in the fisheries ASO database. Across three years of data collection (2016, 2018, and 2019), the number of seabirds reported using the enhanced data collection methods were 0.5–11-fold the number from typical ASO database values. We then used these data to model how the differences between data sources may fluctuate across years. These large discrepancies between the methods highlight the challenges with obtaining accurate seabird bycatch data needed to implement a meaningful ecosystem approach to the management.