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ROBILLARD, A., V. LESAGE, M. HAMMILL, 2005. Distribution and abundance of harbour seals (Phoca vitulina concolor) and grey seals (Halichoerus grypus) in the Estuary and Gulf of St. Lawrence during 1994-2001. Can. Tech. Rep. Fish. Aquat. Sci., 2613, 152 p .
The abundance and distribution of harbour seals and grey seals in the Estuary and Gulf of St. Lawrence was assessed using seven aerial visual surveys of the Estuary, including three in June (1995, 1996, 2000) and four in August (1994-1997), and two surveys flown in June in different areas of the Gulf (1996 and 2001). Harbour seal counts at haul-out sites ranged from 389 to 659 individuals in the Estuary compared with 890 individuals for the regions surveyed in the Gulf. Assuming that the haul-out behaviour of harbour seals in our study area is similar to harbour seals in the eastern Pacific, where it has been estimated that about 50-75 % of seals are hauled out during surveys, there may be approximately 4000-5000 harbour seals in the Estuary and Gulf of St. Lawrence. Trend analyses of the abundance of harbour seals in the Estuary since1994 were inconclusive, owing to the small number of surveys available for the analyses. A total of 111 to 723 grey seals were counted at haul-out sites in the Estuary, far fewer than the 2474 grey seals that were observed during the two surveys of the Gulf of St. Lawrence. No attempt was made to correct for the animals in the water. Haul-out counts varied widely between years, suggesting between-year changes in the use of this area by grey seals.
GOSSELIN, J.-F., V. LESAGE, A. ROBILLARD, 2001. Population index estimate for the beluga of the St. Lawrence River Estuary in 2000. DFO, Canadian Science Advisory Secretariat, Research Document ; MPO, Secrétariat canadien de consultation scientifique, Document de recherche, 2001/049, 21 p .
Abundance of beluga in the St. Lawrence estuary was estimated from an aerial survey flown on 28 August 2000. Two fixed-wing aircrafts equipped with 9"x9" format mapping cameras flew 52 strip transects across the Estuary between Baie St-Paul and Rimouski for a total survey coverage of 49.3%. A visual survey to count beluga in the Saguenay River was flown at the same time. In the estuary, 453 (SE = 54) beluga were estimated to be at the surface between Kamouraska and Les Escoumins after correction for sun glare, and 6 beluga were counted downstream of Baie Ste-Marguerite in the Saguenay River. A 15 % correction factor was applied to the estimated number of beluga at the surface in the estuary to account for beluga missed because they were underwater. Adding the Saguenay River count to the corrected estimate resulted in an index count of 527 (SE = 62). This corrected index used in trend analysis along with 5 equivalent survey indices obtained between 1988 and 1997, revealed no significant changes in abundance of beluga in the St. Lawrence estuary since 1988.
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