Science Advisory Report 2017/024

Assessment of Softshell Clam Stocks in Québec Coastal Waters

Summary

• Softshell clams are present along most of Québec’s shoreline in beds in soft-bottom sediments. They are exploited by commercial and recreational harvesters. The quantities that are harvested recreationally, an activity valued by coastal communities, remain unknown.
• There is no commercial fishery in the Gaspé Peninsula and the Lower St. Lawrence. Landings from the Îles-de-la-Madeleine are low (< 1.3 t) and it is difficult to assess the status of the resource in that location.
• Since 2010, clam landings have come mainly from 11 shellfish areas in sub-areas 1A, 1B and 1C of the Upper North Shore.
• Landings reached a maximum of 1,173 t in 2000 on the Upper North Shore. They then declined to 190 t in 2009, a year prior to the closure of the processing plants. After a few years of low landing numbers, they rose somewhat in 2015 following the re-opening of a plant. Landings amounted to 72 t in 2015 and 83 t in 2016. Total allowable catches (TACs), introduced in 2015, were not met for the vast majority of areas, despite a good price.
• The measure of fishing effort in vendor-day is somewhat uncertain because there may have been more than one harvester per seller, mainly during the intensive exploitation of the early 2000s. This uncertainty also affects the catch per unit effort (kg/vendor-day).
• In 2015 and 2016, the average size of clams landed was between 58 and 74 mm in the exploited areas. The proportion of clams of sub-legal size (< 51 mm) was generally below 5%. However, this proportion was about 10% for the Anse du Colombier, Anse Noire and Îlets Jérémie areas in sub-area 1A.
• The survey conducted in 2014 on the Reserve Pessamit Sud bed suggests a stable density and biomass of legal-size clams compared to the 2010 survey. Surveys were taken in 2016 on the Banc Marie-Marthe and the Baie des Plongeurs. The closure of the Baie des Plongeurs from 2010 to 2015 appears to have favoured the recovery of this bed.
• Despite the low commercial fishing effort in recent years, several areas (e.g. Pointe à Boisvert and Pointe de Mille-Vaches) have not shown a significant improvement in the status of their resources.
• In order to protect the reproductive potential of each shellfish area, it is recommended to collect less than 10% of the commercial biomass annually. To mitigate the incidental mortality caused by the fishery, it is recommended to prohibit any harvesting when the air temperature is ≤ 0 °C.

This Science Advisory Report is from the meeting of February 16, 2017, on the Assessment of Quebec inshore waters Softshell clam. Additional publications from this meeting will be posted on the Fisheries and Oceans Canada Science Advisory Schedule as they become available.

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