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BRULOTTE, S., B. THOMAS, H. BOURDAGES, M. GIGUERE, M. BOUDREAU, 2010. Captage de naissain de pétoncles sur la rive sud de la Gaspésie (Québec) de 1999 à 2004. Rapp. tech. can. sci. halieut. aquat., 2889, 117 p .
Efforts have been deployed over the last decade to assess the breeding potential of sea scallops, Placopecten magellanicus, and Iceland scallops, Chlamys islandica, on the south shore of the Gaspé Peninsula. Results from the work performed between 1999 and 2004 concern scallop spat distribution and other related species between the Bay of Tracadigache and the Bay of Gaspé, their distribution in the water column and their available temporal window for collection. In addition, data was collected on the marine environment (temperature and salinity) and the sea scallops gonadosomatic development status. Stations were divided into three sectors: Bay of Tracadigache (8 stations), Bay of Gaspé (9 stations) and Centre (7 stations along the coast between Tracadigache and Gaspé). Spat collectors were submerged in late August, early September between 1999 and 2003. They were recovered after being submerged 3, 10, 12, 14 and 22 months. Results revealed that the spawning period for sea scallops appears to occur during the last two weeks of August in the Gaspé Peninsula. Sea and Iceland scallops were captured at every station sampled. Spat collection success for both scallop species was different from one station to another, but was not significantly different from one year to the next. Stations in the Bay of Tracadigache and the Bay of Gaspé had the highest number of captured scallops. The ratio between the abundance of the two scallop species varied based on the station and year. However, in many cases, sea scallops dominated in Tracadigache and sometimes in Gaspé. Spat abundance in the collectors decreased with their soak time. Significant attrition occurred in the Bay of Tracadigache between 3 and 10 months of soak time. A drop in the number of sea scallop specimens was also observed between 10 and 14 months of soak time in all sectors. These losses are likely the result of scallops releasing from the collectors and their predation. Furthermore, the intensity of the annual spat collection does not seem consistent with the depth of the collectors in the water column or with the thermocline, even if in some cases the trends observed appear to support this theory. The peak of settlement for spat scallops occurred at mid-October. Scallop growth varied according to the species, location and year. It was faster for sea scallops than Iceland scallops and faster in the Centre and Gaspé sectors than in Tracadigache. Fouling often covered the collectors, but their abundance fluctuated over time and based on the sector. A wide range of species was found in the collectors, around 40 taxa. The dominant species were Hiatella arctica, Mytilus spp. and hydrozoans. Predators, such as Asterias rubens, Cancer irroratus and Hyas spp. were observed in the collectors. Starfish were the most abundant predator. The available window for most of these species coincided with that of the scallops.
GIGUÈRE, M., S. BRULOTTE, M. BOUDREAU, M.-F. DRÉAN, 2008. Évaluation de huit gisements de mye commune (Mya arenaria) de la rive nord de lestuaire du Saint-Laurent de 2002 à 2008. Rapp. tech. can. sci. halieut. aquat., 2821, 101 p .
Between 2002 and 2008, work was conducted on the shoreline of the Upper North Shore, between Tadoussac and Pointe-aux-Outardes, to describe the status of eight softshell clam (Mya arenaria) populations. The beds that were examined were, from west to east, Baie du Moulin à Baude, Baie des Petites Bergeronnes, Pointe à Émile, Baie des Chevaux, Cran à Gagnon, Anse Noire, Réserve Betsiamites Sud and Pointe-aux-Outardes. All these beds were located at the mouth of rivers or creeks. Sampling grids, which were systematic, were adjusted to account for the size and shape of the surveyed sites. The top of each grid was set at of the intertidal zones upper limit and its base at the level corresponding to the zero chart datum. The grid comprised between 20 and 173 stations depending on sites. A vacuum-type apparatus, providing a Venturi effect, was used to collect organisms when sediment was malleable and the water layer was more than 10 cm. Otherwise, a shovel was used. Organisms and sediment were collected over a 0.25 m2 area to a depth of 0.30 m. The results present altimetry, sediment, plant cover, benthic species present and dominant, as well as a few biological characteristics of the softshell clam populations. The dominant sediment was sandy silt at Pointe à Émile, Baie des Chevaux, Cran à Gagnon and Anse Noire, sand at Réserve Betsiamites Sud, sand and gravelly sand at Baie du Moulin à Baude and gravelly sand at Baie des Petites Bergeronnes and Pointe-aux-Outardes. There was little or no eelgrass (Zostera marina) at many of the inventoried sites. Macoma balthica was, along with softshell clams, the most common species, followed by polychaetes, Mytilus edulis and Mesodesma arctatum. The highest average densities, between 183 and 175 softshell clams/m2, were recorded respectively at Pointe à Émile and Baie des Chevaux. The lowest average densities, under 51 clams/m2, were recorded at Baie des Petites Bergeronnes, Pointe-aux-Outardes and Baie du Moulin à Baude. Maximum densities varied from 136 clams/m2 (Baie du Moulin à Baude) to 2,204 clams/m2 (Réserve Betsiamites Sud). The highest average densities of legal size softshell clams (10-27 clams/m2) were recorded at Baie du Moulin à Baude, Réserve Betsiamites Sud, Pointe-aux-Outardes, Baie des Petites Bergeronnes and Cran à Gagnon. For the other beds, values varied between 1.6 and 9.1 clams/m2. The maximum size of softshell clams harvested was larger at Réserve Betsiamites Sud (107 mm) and Pointe-aux-Outardes (102 mm) and smaller at Pointe à Émile (55 mm) and Anse Noire (60 mm). The results obtained indicated that legal size softshell clams were generally more abundant on sand and gravelly sand foreshores than on silty sand foreshores. The largest sizes are likely reached in sand and silty sand habitats. However, large sizes can also be reached in sandy silt such as at Baie des Chevaux and Cran à Gagnon. Comparing our results with other data from around 40 years ago showed that the condition of some of the beds has regressed, probably as a reaction to to the exploitation of these populations which has been intense at times.
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