First demographic insights on historically harvested and poorly known male sperm whale populations off the Crozet and Kerguelen Islands (Southern Ocean)

Guillemette Labadie
Paul Tixier
Christophe Barbraud
Rémi Fay
Nicolas Gasco
Guy Duhamel
Christophe Guinet
Age and sex dependent spatial segregation has resulted in limited knowledge of the ecology and demography of sperm whale adult males feeding seasonally in high latitudes. This study focused on adult males interacting with the Patagonian toothfish (Dissostichus eleginoides) fishery operating off the Kerguelen and Crozet Archipelagos. Demographic parameters were estimated using a 10-yr-long photoidentification data set paired with multistate closed robust design capture-markrecapture models. The examination of a set of 29,078 photographs taken from fishing vessels during sperm whale depredation events resulted in identification of 295 individuals with nine visiting both study areas. Dispersal between both study regions was estimated to be 1\% per year. The mean annual number of interacting sperm whales was estimated to n = 82 (95\% CI 58–141) in Crozet and n = 106 (95\% CI 76–174) in Kerguelen. Transient proportions were 13\% in Crozet and 26\% in Kerguelen. Corrected for transience, apparent survival estimates were 0.953 (95\% CI 0.890–0.993) in Crozet, and 0.911 (95\% CI 0.804–0.986) in Kerguelen. These survival and population size estimates are the first for depredating adult males in high latitudes, and can be used in evaluating the current conservation status of this historically harvested stock and to investigate depredation trends in 35 both Crozet and Kerguelen Islands.
Année de publication
Marine Mammal Science
Nombre de pages
Date de publication
Numéro ISSN
Labadie, Guillemette, Paul Tixier, Christophe Barbraud, Rémi Fay, Nicolas Gasco, Guy Duhamel et Christophe Guinet. « First Demographic Insights On Historically Harvested And Poorly Known Male Sperm Whale Populations Off The Crozet And Kerguelen Islands (Southern Ocean) ». Marine Mammal Science 34 (2018), 595-615. doi:10.1111/mms.12469.