Research Document - 2013/082
Assessment of Atlantic surfclam, Spisula solidissima, in the coastal waters of the Îles-de-la-Madeleine, Québec – methodology and results
By Brulotte, S.
Abstract
In Québec, the Atlantic surfclam fishery is practiced exclusively in the Îles-de-la-Madeleine. The fishery is conducted in two different ways, either by boat with a hydraulic dredge in coastal waters, or manually on foot or while diving in lagoons or near the coast. Fishing Area 5 in the Îles-de-la-Madeleine is divided into four sub-areas, and dredge fishery is primarily conducted in sub-areas 5A1 and 5B1. Hand digging may be recreational or commercial, and is conducted in approximately 10 shellfish sectors.
In 2012, landings of commercial dredge fishery reached 134 t with an effort of 21 days in 5A1 and 103 t for 20 days in 5B1. Since 2008, catch per unit effort (CPUE) has been increasing in 5A1 and reached a record high of 314 kg per hour/meter (kg/hm) in 2012. In 5B1, annual CPUE has been relatively stable since 2009. Over the past three years, the average size of landed surfclam has been the same or greater than the reference average in sub-areas 5A1 and 5B1. The shift in fishing effort to new portions of surfclam beds from one year to another resulted in good yields and stable size structures. From 2010 to 2012, the proportion of known beds dredged annually was 3% in 5A1 and 13% in 5B1. Sub-area 5A2 has not been fished since 2002, and fishing effort has been sporadic and low in sub-area 5B2.
The available information on hand digging, either on foot or while diving, is limited. This type of harvesting is very popular and well-developed. The average known annual landings from commercial hand digging is about 22 t; however, this value is underestimated and the amount of surfclam harvested recreationally is unknown. Since 2010, the annual CPUE calculated from commercial harvesting on foot or while diving has been under the respective reference averages. The area of three hand harvested beds was determined in 2012. These beds are nearly all accessible on foot. The surfclam density of two of these beds, located in the Grande Entrée lagoon, is lower than that observed in 2007.
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