Mitigating bycatch of Southern Gulf of St. Lawrence NAFO Division 4T White Hake (Urophycis tenuis)

Abstract

Key management measures proposed in the southern Gulf of St. Lawrence White Hake (Urophycis tenuis) rebuilding plan include keeping removals from all sources at the lowest possible level, monitoring sources of fishing mortality, and enforcing compliance of management measures. In this study, we assessed spatial and temporal patterns of bycatch risk in four fisheries responsible for the majority of White Hake bycatch from 2013 to 2022. To assess bycatch risk, we used fisheries-independent and/or fisheries-dependent data in species distribution models, and we compared model predictions under different fishing scenarios to develop fishery-specific considerations for Fisheries and Harbour Management. Occurrence and density of White Hake were associated with depth, making depth-specific mitigation an important component of bycatch mitigation strategies for the Redfish fishery and possibly the Greenland Halibut and Witch Flounder fisheries. For the Greenland Halibut and Atlantic Halibut fisheries, locations and/or months of high bycatch risk were identified in which mitigation efforts could be focused. The vast majority of surveys and fishing activities occurred from May to October, however, a reopened commercial Redfish fishery operating between January and May is likely to overlap with the overwintering habitat of White Hake and other groundfish. During winter months, stricter depth-associated mitigation strategies may be warranted.