title: First Direct Evidence for Natal Wintering Ground Fidelity and Estimate of Juvenile Survival in the New Zealand Southern Right Whale Eubalaena australis.
abstract: Juvenile survival and recruitment can be more sensitive to environmental, ecological and anthropogenic factors than adult survival, influencing population-level processes like recruitment and growth rate in long-lived, iteroparous species such as southern right whales. Conventionally, Southern right whales are individually identified using callosity patterns, which do not stabilise until 6-12 months, by which time the whale has left its natal wintering grounds. Here we use DNA profiling of skin biopsy samples to identify individual Southern right whales from year of birth and document their return to the species' primary wintering ground in New Zealand waters, the Subantarctic Auckland Islands. We find evidence of natal fidelity to the New Zealand wintering ground by the recapture of 15 of 57 whales, first sampled in year of birth and available for subsequent recapture, during winter surveys to the Auckland Islands in 1995-1998 and 2006-2009. Four individuals were recaptured at the ages of 9 to 11, including two females first sampled as calves in 1998 and subsequently resampled as cows with calves in 2007. Using these capture-recapture records of known-age individuals, we estimate changes in survival with age using Cormack-Jolly-Seber models. Survival is modelled using discrete age classes and as a continuous function of age. Using a bootstrap method to account for uncertainty in model selection and fitting, we provide the first direct estimate of juvenile survival for this population. Our analyses indicate a high annual apparent survival for juveniles at between 0.87 (standard error (SE) 0.17, to age 1) and 0.95 (SE 0.05: ages 2-8). Individual identification by DNA profiling is an effective method for long-term demographic and genetic monitoring, particularly in animals that change identifiable features as they develop or experience tag loss over time.
authors.affiliation: School of Biological Sciences, University of Auckland, Auckland, New Zealand.|Scottish Oceans Institute, University of St Andrews, East Sands, St Andrews, Scotland.
authors.forename: E L
authors.initials: EL
authors.lastname: Carroll
authors.affiliation: Department of Statistics, University of Auckland, Auckland, New Zealand.
authors.forename: R M
authors.initials: RM
authors.lastname: Fewster
authors.affiliation: Blue Planet Marine, Kingston, Hobart, Tasmania, Australia.
authors.forename: S J
authors.initials: SJ
authors.lastname: Childerhouse
authors.affiliation: Collégial International Sainte-Anne, Montréal, Québec, Canada.
authors.forename: N J
authors.initials: NJ
authors.lastname: Patenaude
authors.affiliation: New Zealand Department of Conservation, Wellington, New Zealand.
authors.forename: L
authors.initials: L
authors.lastname: Boren
authors.affiliation: School of Biological Sciences, University of Auckland, Auckland, New Zealand.|Marine Mammal Institute and Department of Fisheries and Wildlife, Hatfield Marine Science Center, Oregon State University, Newport, United States of America.
authors.forename: C S
authors.initials: CS
authors.lastname: Baker
mesh_terms: D025041:Animal Migration; D000818:Animals; D001706:Biopsy; D005260:Female; D014644:Genetic Variation; D005838:Genotype; D005843:Geography; D008297:Male; D009520:New Zealand; D011156:Population Density; D011157:Population Dynamics; D012621:Seasons; D017422:Sequence Analysis, DNA; D012867:Skin; D014907:Whales / Q000254:growth & development / Q000502:physiology*