Estimation of juvenile survival, adult survival, and age-specific pupping probabilities for the female grey seal (Halichoerus grypus) on Sable Island from capture-recapture data

• Published in: Canadian journal of fisheries and aquatic sciences 2000-01, Vol.57 (1), p.247-253
• Main Authors: Schwarz, C J, Stobo, W T
• Format: Article
• Language: English
• Subjects: Canada, Nova Scotia, Sable I; Halichoerus grypus; Marine
• ISSN: 0706-652X; 1205-7533
• DOI: 10.1139/cjfas-57-1-247

A longitudinal capture-recapture study is used from resightings of grey seals (Halichoerus grypus) branded as young on Sable Island to estimate (1) the juvenile survival rate from the time of branding to age 4, (2) the yearly adult survival rate from age 4 to 9, and (3) the age-specific pupping probabilities, i.e., the probability that a seal will first give birth at each age. The estimated juvenile survival rate from branding (just after weaning) to age 4 ranged from 70 to 80%; however, the lower values are known to be biased low because the study was terminated early. The estimated yearly adult survival rates for ages 4-9 ranged from 0.88 to 0.92 times year super(-1). The estimated probabilities of first giving birth to a young seal (pupping) at ages 4-9 are 0.28, 0.41, 0.18, 0.06, 0.05, and 0.02, respectively, and the estimated average age of first pupping is 5.2 years.