scholarly journals Abundance of Northwest Atlantic grey seals in Canadian waters

2007 ◽  
Vol 6 ◽  
pp. 99 ◽  
Author(s):  
M O Hammill ◽  
J F Gosselin ◽  
G B Stenson
Keyword(s):  
Nova Scotia ◽  
Population Model ◽  
Aerial Survey ◽  
Small Islands ◽  
Grey Seal ◽  
Eastern Shore ◽  
Northwest Atlantic ◽  
Survey Techniques ◽  
Pack Ice ◽  
Seal Population

Northwest Atlantic grey seals form a single stock, but for management purposes are often considered as 2 groups. The largest group whelps on Sable Island, 290 km east of Halifax, Nova Scotia. The second group referred to as ‘non-Sable Island’ or ‘Gulf’ animals whelps primarily on the pack ice in the southern Gulf of St. Lawrence, with other smaller groups pupping on small islands in the southern Gulf and along the eastern shore of Nova Scotia. Estimates of pup production in this latter group have been determined using mark-recapture and aerial survey techniques. The most recent visual aerial surveys flown during January-February 1996, 1997 and 2000 in the southern Gulf of St Lawrence and along the Eastern Shore resulted in pup production estimates of 11,100 (SE = 1,300), 7,300 (SE = 800) and 6,100 (SE = 900) in 1996, 1997 and 2000 respectively after correcting for births and including counts of pups on small islands. Incorporating information on pup production, reproduction rates and removals into a population model indicates that the Gulf component increased from 15,500 (95% CI = 14,600-16,300) animals in 1970 to 62,700 (95% CI = 49,800-67,800) animals by 1996 and then declined to 22,300 (95% CI = 17,200-28,300) animals in 2000. On Sable Island the population has increased from 4,800 (95% CI = 4,700-4,900) animals in 1970 to 212,500 (95% CI = 159,600-276,200) in 2000. The total Northwest Atlantic grey seal population is estimated to number around 234,800 animals in 2000.

Pup production and population trends of the grey seal (Halichoerus grypus) in the Gulf of St. Lawrence

1998 ◽  
Vol 55 (2) ◽  
pp. 423-430 ◽  
Author(s):  
M O Hammill ◽  
G B Stenson ◽  
R A Myers ◽  
W T Stobo
Keyword(s):  
Population Trends ◽  
Annual Rate ◽  
Halichoerus Grypus ◽  
Grey Seal ◽  
Northwest Atlantic ◽  
Mark Recapture ◽  
Seal Population ◽  
Independent Estimate ◽  
Anticosti Island

Grey seal (Halichoerus grypus) pup production of the Gulf of St. Lawrence component of the Northwest Atlantic grey seal population was determined for the 1984-1986 and 1989-1990 periods using mark-recapture methods. Pup production estimates based on recaptures from shot samples from Anticosti Island ranged from 5436 (SE = 672) to 6955 (SE = 1183) for 1984-1986. An independent estimate for 1984-1986, based on animals captured on Sable Island, was 7431 (SE = 1414) to 8633 (SE = 2827). Mark-recapture estimates of pup production for 1989 and 1990 from shot samples collected from Anticosti Island were 8825 (SE = 3164) and 9156 (SE = 2652), respectively. The estimates based on animals captured on Sable Island varied from 7295 (SE = 2118) to 8116 (SE = 846) for 1989-1990. Both the Anticosti Island and Sable Island recovery samples underestimate 1989 pup production due to hunting which removed 1612 pups from the population before they could disperse. The Gulf component of the Northwest Atlantic grey seal population is increasing at an annual rate of 7.4% (SE = 2.2).

scholarly journals Estimates of the size of the Baltic grey seal population based on photo-identification data

2007 ◽  
Vol 6 ◽  
pp. 163 ◽  
Author(s):  
Lex Hiby ◽  
Torkel Lundberg ◽  
Olle Karlsson ◽  
John Watkins ◽  
Mart Jüssi ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Population Based ◽  
Point Estimate ◽  
Grey Seal ◽  
The Baltic Sea ◽  
Photo Identification ◽  
A Value ◽  
Seal Population ◽  
The Baltic ◽  
Year 2000

The size of the year 2000 summer population of grey seals in the Baltic Sea was estimated using identification of individual seals from photographs taken over a period of 6 years. Photos were taken at haul-out sites within all major grey seal areas in the semi-closed Baltic Sea. The point estimate is 15,631, based on a value for annual survival of identification markings of 0.904, which was also estimated using the photo-id data, with 95% confidence limits from 9,592 to 19,005. The estimate is subject to an unknown, but probably small, upward bias resulting from the risk of failure to identify all individuals in the photographs used for the analysis. An estimated minimum of 15,950 seals were counted at moulting haul-outs in 2003, which thus provides a lower bound on the population size in that year and represents 80% of the photo-id point estimate.

Aerial Survey Techniques for Locating Abandoned Strip Mine Land

1980 ◽  
Vol 9 (4) ◽  
pp. 606-610
Author(s):  
L. E. Dattavio ◽  
R. P. Mroczynski ◽  
R. A. Weismiller
Keyword(s):  
Aerial Survey ◽  
Survey Techniques ◽  
Strip Mine

Diving behaviour during the breeding season in the terrestrially breeding male grey seal: implications for alternative mating tactics

2003 ◽  
Vol 81 (6) ◽  
pp. 1025-1033 ◽  
Author(s):  
Damian C Lidgard ◽  
Daryl J Boness ◽  
W Don Bowen ◽  
Jim I McMillan
Keyword(s):  
Nova Scotia ◽  
Reproductive Success ◽  
Breeding Season ◽  
Foraging Behaviour ◽  
Diving Behaviour ◽  
Halichoerus Grypus ◽  
Phenotypic Traits ◽  
Alternative Mating Tactics ◽  
Grey Seal ◽  
Mating Tactics

We examined the diving behaviour of breeding male grey seals (Halichoerus grypus) at Sable Island, Nova Scotia, from 1997 to 2001. The proportion of time spent at sea varied between 0 and 78% (N = 30). Males engaged in deep (43.4 ± 3.3 m (mean ± SE), N = 27) diving, and these dives were clustered into bouts, which mostly occurred during long trips (62.2 ± 14.7 h). We suggest that males spent time foraging during deep dives. Shallow diving (5.9 ± 0.1 m, N = 27) accounted for 40.8% of dives, which were also clustered into bouts that mostly occurred during short trips (2.1 ± 0.37 h). We suggest that shallow diving comprised a suite of behaviours, but included little foraging behaviour. Phenotypic traits had little influence on diving behaviour. Further work is required to understand the extent to which foraging behaviour enhances reproductive success, and whether shallow diving is a component of the mating tactics of male grey seals at Sable Island.

scholarly journals Sustained exponential population growth of grey seals at Sable Island, Nova Scotia

2003 ◽  
Vol 60 (6) ◽  
pp. 1265-1274 ◽  
Author(s):  
W.D Bowen ◽  
J McMillan ◽  
R Mohn
Keyword(s):  
Nova Scotia ◽  
Statistical Model ◽  
Aerial Photography ◽  
Environmental Variability ◽  
Grey Seal ◽  
Confidence Limits ◽  
The World ◽  
The Face ◽  
Exponential Population Growth ◽  
Exponential Population

Abstract Grey seal pup production on Sable Island, Nova Scotia, has been monitored since the early 1960s. We estimated pup production on Sable Island in 1997 using aerial photography with a correction for detection of pups on the imagery and a statistical model to account for the proportion of pups not born at the time of the survey. A total of 20 863 pups were counted on the colour positives. When corrected for the proportion of pups seen on the imagery (0.96) and the proportion of pups born before the survey (east colony 0.94, west colony 0.66), estimated total pup production was 25 400 with approximate 95% confidence limits of 23 500 and 26 900. The 1997 estimate indicates that pup production in this population, now the largest grey seal colony in the world, has been increasing exponentially at an annual rate of 12.8% for four decades in the face of considerable environmental variability.

Seals in the Inner Hebrides

1983 ◽  
Vol 83 ◽  
pp. 219-228
Author(s):  
R. William Vaughan
Keyword(s):  
Insufficient Data ◽  
Grey Seal ◽  
Seal Population ◽  
The Common

SynopsisAbout 10% of the British grey seal population and 20% of the British common seal population breed around the Inner Hebrides. Grey seals occur on the more exposed coasts whereas common seals inhabit the more sheltered waters and the inner reaches of sea lochs. There is some evidence of an increase in grey seal numbers, but there are insufficient data to assess the exact status of the common seal.

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