Évaluation des stocks de buccin au Québec : résultats de la pêche commerciale (1987-2024) et du relevé de recherche (2005-2024)

Abstract

The Waved whelk, Buccinum undatum, is a gastropod mollusc found along the Estuary and Gulf of St. Lawrence. In Quebec, it can reach a shell height of 120–130 mm, but individuals larger than 105 mm are increasingly rare. Its growth rate is fairly slow and its life span is at least 15 years. There are 15 whelk fishing areas in Quebec. The whelk fishery is an inshore fishery that uses traps. It focuses essentially on Buccinum undatum, although some other species of Buccinum are present. The fishery is regulated by the number of licences, the number of traps and the minimum legal size which varies according to the fishing areas. Quotas on landings are in place in six areas. The stock status is determined primarily based on commercial fishery indicators. In 2024, Quebec landings totalled 407 t, of which 73% were from the North Shore, 24% from the Magdalen Islands and 4% from the Gaspé Peninsula–Lower St. Lawrence. Landings had decreased in most fishing areas compared to 2019-2021. For areas managed by a total allowable catch (TAC), it has never or very rarely been reached in areas 1, 2, 12, 13 and 15. The average catch per unit effort (CPUE) in 2022–2024 was below the historical average (2002–2021) in areas 1 (-24%), 2 (-40%), 3 (-54%), 4 (-16%), 5 (-29%), 6 (-34%), 7 (-54%) and 8 (-19%) on the North Shore; in areas 12 (-60%) and 13 (-50%) in the Gaspé–Lower St. Lawrence region; and in area 15 (-28%) in the Magdalen Islands. The status of these stocks is worrisome, with downward trends and local decreases in CPUE values observed in most areas. These stocks do not appear to be able to sustain the current fishing effort and consequently are vulnerable to overfishing and local depletion. Following a recent assessment of size at sexual maturity in a number of fishing areas, the minimum legal size was increased in 2023 in areas 4, 5, 6, 7 (from 80 to 85 mm) and areas 8, 11, 12 and 14 (from 75 to 80 mm), and in 2024 in area 13 (from 75 to 80 mm). These changes could partly explain the decline in landings and CPUE values observed in recent years. In the past few years, the proportion of sub-legal-size whelk landed has been below 5% in all fishing areas, except for areas 2 (2022–2023), 4 (2022–2023), 6 (2023), 7 (2024) and 8 (2022, 2023 and 2024). The densities of legal-size whelk and juvenile recruits observed in the research survey (conducted every two years) in 2024 in areas 1 and 2 on the Upper North Shore were lower than those in the 2022 survey, and are among the lowest values in the time series (2005–2024).