Application of Removal Sampling to Estimate the Density of Ringed Seals ( Phoca hispida ) in Barrow Strait, Northwest Territories

• Published in: Canadian Journal of Fisheries and Aquatic Sciences
• Main Authors: Hammill, M. O., Smith, T. G.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1990
• Subjects: Aquatic Science; Ecology, Evolution, Behavior and Systematics; Northwest Territories; Barrow Strait; Phoca hispida
• Online Access: http://dx.doi.org/10.1139/f90-027; http://www.nrcresearchpress.com/doi/pdf/10.1139/f90-027

The density of ringed seals (Phoca hispida) in 2 to 4 km 2 study plots was determined using a combination of removal sampling to determine density of seal holes and estimates of hole to seal ratios. A dog survey technique was adapted to removal sampling, where seal holes located under the snow by the dogs during surveys of fixed effort were marked and treated as removals from the population. Computer simulation indicates that estimates of seal hole density are within 10% of the true population size if for each plot there are [Formula: see text] searches, sampling intensity is [Formula: see text], the coefficient of variation of the estimate is [Formula: see text], and the probability of detecting a seal hole is [Formula: see text]. The quality of survey results was affected by the number of dogs used to survey each plot, plot size, and surface topography. Densities of seal holes varied from 4.8 to 7.9 holes∙km −2 . Eight seals had an average hole to seal ratio of 3.4. Seal densities ranged from 1.4 to 2.3 seals∙km −2 , and may be much higher if pup production is included.