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HAMMILL, M.O., G.B. STENSON, T. DONIOL-VALCROZEL, A. MOSNIER, 2011. Northwest Atlantic harp seals population trends, 1952-2012 ; Tendances de la population de phoques du Groenland de l'Atlantique Nord-Ouest, 1952-2012. DFO, Canadian Stock Assessment Secretariat, Research Document ; MPO, Secrétariat canadien de consultation scientifique, Document de recherche, 2011/099, 31 p .
A population model was used to examine changes in the size of the Northwest Atlantic harp seal population between 1952 and 2012. The model incorporated information on reproductive rates, reported removals, estimates of non-reported removals and losses through bycatch in other fisheries to determine the population trajectory. Reproduction rates have continued to decline. Samples collected up to 2011, indicate that adult reproductive rates have declined to as low as 0.22, which is much lower than the estimate of 0.74 observed for 2008, the last year data were available for the 2010 assessment. The model was fit to eleven estimates of pup production from 1952 to 2008, using two different methods of smoothing the reproductive data and assuming carrying capacity can be either 10.8 million or 12 million seals. Estimated pup production in 1952 was 500,000 (95 % CI=500,000-600,000) animals. Pup production declined throughout the 1960s reaching a minimum 1971, and then increased to a maximum of 1,600,000 (95 % CI=1,400,000-1,800,000) in 2008. Estimated pup production declined to 600,000 (95 % CI=500,000-700,000) in 2011 due to the low pregnancy rates observed. The total population size in 1952 was 2,300,000 (95 % CI=2,200,000 -2,400,000) declining to a minimum in 1971 and then increasing to 7.9 to 8.3 million (95 % CI=7,300,000-9,000,000) in 2008, depending upon the assumptions. The 2008 estimate is also Nmax. The 2012 population is estimated to be 7.3 to 7.7 million. Although the previous assessment indicated that a harvest of 400,000 could be sustained for the remainder of the management period, the maximum harvest that would respect the management plan under this assessment is 300,000 animals, assuming that beaters comprise 97 % of the harvest. The difference is due to the significant decline in reproductive rates observed in samples collected since 2008. Increasing catches on one component of the population through a transfer of quota will adversely impact that component unless it is offset by an equal reduction in subsequent years
MOSNIER, A., V. LESAGE, J.-F. GOSSELIN, S. LEMIEUX LEFEBVRE, M.O. HAMMILL, T. DONIOL-VALCROZE, 2009. Information relevant to the documentation of habitat use by St. Lawrence Beluga (Delphinapterus leucas), and quantification of habitat quality ; Information pertinente à la documentation de l'utilisation de l'habitat par le béluga du St-Laurent (Delphinapterus leucas) et à la quantification de la qualité de l'habitat. DFO, Canadian Science Advisory Secretariat, Research Document ; MPO, Secrétariat canadien de consultation scientifique, Document de recherche, 2009/098, 39 p .
The current population size and distribution range of St. Lawrence beluga are a fraction of those used historically. Their core distribution is centered on the Saguenay River, and is now located between the Battures-aux-Loups-Marins and Rivière-Portneuf / Rimouski in the Estuary, and Baie Ste-Marguerite in the Saguenay River. Concentration areas outside of this sector vary seasonally, as they did in the 1930s, but are now constrained within a zone located between Battures-aux-Loups-Marins and Sept-Îles / Cloridorme (vs west of Quebec City to Natashquan in the 1930s), with only rare observations in the Baie des Chaleurs. St. Lawrence beluga distribution range is small compared to other beluga populations, and even smaller during summer. The timing and extent of seasonal movements of beluga are likely dictated by at least three key drivers: sea ice, predation risks, and food availability. However, little is known about beluga distribution outside of summer. Currently available knowledge indicates that sex- and agesêcific spatial segregation is typical of the species during summer. The Upper Estuary, where females accompanied by calves and juveniles concentrate, is likely an important habitat for calving and juvenile rearing. Reasons for sexual segregation and habitat characteristics that are critical to the survival of females, juveniles and calves in this sector are unclear. The species also consistently aggregates at certain river mouths during summer, which suggest that they are an essential part of beluga habitat. The functions of these areas are unknown. Several smaller areas where beluga occur on a regular basis or where they spend relatively large proportions of their time exist within their seasonal distribution area, some of which have been identified for the summer period. However the current understanding of the functions and key features of these habitats and of habitat use and movements among these areas by beluga does not allow the assessment of their relative importance for the survival of the population. Given that current distribution is small relative to that used historically, a degradation of key habitat features or a reduction in key habitat availability would probably result in negative effects on recovery. In this context, preserving access to and integrity of areas used currently or historically by a large proportion of the population is considered important for the recovery and future range expansion of the population. Species characteristics such as longevity, social organization and learned behaviours may influence seasonal habitat use, and might delay re-colonization of areas used historically.
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