Research Document 2023/073

Stock assessment of whelks in Quebec: Results from the commercial fishery (2002 – 2021) and scientific surveys (2005 – 2019)

By Gianasi, B.L.

Abstract

The Waved whelk, Buccinum undatum, is a gastropod mollusc that is 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 Québec. 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 of commercial fishery indicators.

In 2021, Quebec landings totalled 910 t, of which 73% were from the North Shore, 18% from the Îles-de-la-Madeleine and 8% from the Gaspé Peninsula–Lower St. Lawrence. Landings had decreased in most fishing areas compared to 2017. For areas managed by a total allowable catch (TAC), landings were below the TAC in Areas 1, 12, 13 and 15; however, landings exceeded the TAC by 4.2 t (3.8% of the current TAC) in Area 2. The percentage of undersized whelk landed was below 4%, except in Area 8 (5.8%). The trend in catch per unit effort (CPUE) over the 2018-2021 period is positive in Area 8, relatively stable in Areas 1 and 2, and declining in Areas 3, 4-5, 6, 12, 13, and 15. More specifically, the stock status in some areas of the Gaspé Peninsula (Areas 12 and 13), the Middle North Shore (Areas 3, 4, 5 and 6) and the Îles-de-la-Madeleine (Area 15) is of concern. These stocks do not seem to be able to sustain the current fishing effort over the long term and are therefore vulnerable to overexploitation and local depletion. According to a recent assessment, the minimum legal size (MLS) should be adjusted to the average size at which 50% of female Buccinum undatum are sexually mature (T₅₀). Such an adjustment would represent an increase in MLS for Areas 4, 5, 6, 7, 8, 12 and 13.

The research survey conducted in 2019 in Areas 1 and 2 showed that the density of commercial size whelks (≥70 mm) decreased from 2017 at Forestville, Pointe-aux-Outardes and Baie-Comeau sites. In addition, total whelk density (≥20 mm) was significantly lower than the highest value observed historically.

Research Document 2023/073 (PDF, 10,786 KB)

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