Science Advisory Report 2024/025

Assessment of the Îles-de-la-Madeleine Atlantic Surfclam Stock in 2023

Summary

• The Atlantic Surfclam fishery in the Îles-de-la-Madeleine is conducted with hydraulic dredges in sub-areas 5A1 and 5B1 or using hand tools, on foot or while diving, in about 10 shellfish areas located in lagoons or near coasts.

Hydraulic dredge fishery

• Three beds are currently known in sub-areas 5A1 and 5B1. The Chenal de la Grande-Entrée (CGE) and East beds are located in sub-area 5A1, and the North bed straddles sub-areas 5A1 and 5B1. Since 2012, harvesting has been mainly focused on the North bed, but resumed on the CGE bed in 2019.
• Over the past three years (2021-2023), the number of active harvesters has fluctuated between two and four, whereas it was between three and four for 2018–2020.
• Total allowable catches (TACs) have not been reached in sub-areas 5A1 and 5B1 since 2019, and average landings for 2021–2023 (177 t) are below the historical average (193 t, 2002–2020). The drop in landings is partly due to the decline in the number of active fisherman.
• When harvesting resumed on the CGE bed in 2019, the non-standardized catch per unit effort (CPUE) was high (347 kg/h·m). Although the average for the last three years (232 kg/h·m) is above the historical average (176 kg/h·m, 2002–2020), it shows a downward trend. For the North bed, CPUE was high in 2021 (330 kg/ h·m), but has been falling since. The average 2021–2023 (215 kg/h·m) is slightly below the historical average (233 kg/h·m, 2002–2020).
• Landed surfclam sizes remain stable and over 130 mm in all sampled beds.
• In recent years, the dredged area has decreased on the North bed, but it has increased on the CGE bed, with the resumption of harvesting in 2019. The proportion dredged of the known surface area of the North bed has varied between 2% and 3%, and that of the CGE bed between 7% and 10% between 2021 and 2023.
• Since 2002, fishing effort is sporadic and low in sub-areas 5A2 and 5B2; stock status is therefore unknown in these two sub-areas.
• Declining landings and CPUEs in recent years suggest that harvesting rates may be too high in sub-areas 5A1 and 5B1, despite shifting some of the fishing effort between the harvested beds (CGE and North).

Hand digging

• Commercial and recreational clam digging by divers and shore harvesters is well-developed in the Îles-de-la-Madeleine. However, the extent of manual recreational harvesting is not well known.
• Reported commercial landings from hand digging vary with fishing effort. Between 2021 and 2023, average landings for diving (37 t) and hand digging (14 t) remained above their historical averages (2002–2020) of 22 t and 11 t, respectively.
• For dive harvesting, CPUEs in the two most harvested areas are relatively stable (46 kg/h in A-09.5) or increasing (72 kg/h in A-12.1) compared with their historical averages (2005–2020) of 54 and 69 kg/h·m, respectively. The average size of surfclams landed has also been stable at about 130 mm in 2021–2023.
• For shore harvesting, CPUEs in A-09.5 and A-17.1 have increased to 33 and 26 kg/h (2021–2023), compared with their respective historical averages of 26 and 21 kg/h (2005–2020). The average size of surfclams landed has been around 120 mm for the last three years.
• The number of inactive licences relative to the number of licences issued (latent effort) is still high for both dive (88%) and shore (69%) harvesting. It is unclear whether the resource in the shellfish areas could support the deployment of the total fishing effort. 
• Based on this information, hand harvesting could be maintained at the current level. Any measures that will help better document hand digging fishery are desirable.

This Science Advisory Report is from the February 29, 2024, regional peer review on the Stock Assessment of Atlantic Surfclam of the Magdalen Islands. Additional publications from this meeting will be posted on the Fisheries and Oceans Canada (DFO) Science Advisory Schedule as they become available.

Science Advisory Report 2024/025 (PDF, 1,582 KB)

Data sets:

• Commercial catches sampling program in the Estuary and Gulf of St. Lawrence – Atlantic surfclam (Spisula solidissima)

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