Research Document 2021/059
Gulf of St. Lawrence (4RST) Greenland Halibut Stock Status in 2020: Commercial Fishery and Research Survey Data
By Gauthier, J., Marquis, M.-C., and Isabel, L.
Abstract
The Gulf of St. Lawrence Greenland halibut (Reinhardtius hippoglossoides) stock (NAFO Divisions 4RST) is assessed and managed on a two-year cycle. The indicators used for this assessment are taken from fishery statistical data, sampling of commercial catches and research surveys. This document presents the data, techniques, analyses and results used in a peer review meeting held on February 23 and 24, 2021 via the Zoom platform (virtual meeting).
The directed Greenland halibut fishery developed in the late 1970s. Since the closure of the mobile gear fishery in 1993, this fishery has been carried out almost exclusively with gillnets. Fishing effort is deployed in three main sectors: the western Gulf of St. Lawrence, the area north of Anticosti Island and Esquiman Channel. During the 2000-2020 period, the proportion of the fishing effort deployed in each of these three sectors was 67%, 6% and 24% respectively. The total allowable catch (TAC) remained fixed at 4,500 t between the management years 2004-2005 and 2017-2018. Landings have declined since the 2011-2012 season. In 2018, following a full assessment of the stock status in an interim year, the TAC was reduced at 3,750 t for the 2018-2019 fishing season. The TAC was further reduced for the 2020-2021 fishing season to 2,250 t and preliminary landings totaled 1,330 t. From 2019 to 2020, the commercial fishing performance indices were stable for the western Gulf and Esquiman sectors, while it was increasing in the north Anticosti sector. The indices of the three sectors are below the average of their respective series. According to scientific surveys by DFO and mobile sentinel program, the abundance and biomass indices of Greenland halibut generally showed a downward trajectory from the end of the 2000s to 2019. These indices increased slightly between 2019 and 2020 to levels well below the peaks of the 2000s. This increase is caused by the arrival of the strong 2018 cohort.
The Gulf of St. Lawrence is undergoing major changes: deep waters are warming and becoming depleted of oxygen. These changes can lead to habitat degradation, decreased growth, increased natural mortality and can negatively affect the productivity of Greenland halibut. In addition, changes in the structure of the community (high abundance of redfish and low abundance of shrimp) can modify the interactions of competition for food resources or for habitat. Current environmental conditions and climate projections suggest that the situation is likely to worsen.
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