title: Pathologic Findings and Trends in Mortality in the Beluga (Delphinapterus leucas) Population of the St Lawrence Estuary, Quebec, Canada, From 1983 to 2012.
abstract: An isolated population of beluga (Delphinapterus leucas) inhabits the St Lawrence Estuary, Quebec, Canada. This population has failed to recover despite the prohibition of hunting >30 years ago, suggesting the presence of other limiting factors. The authors summarize the reported causes of death and propose risk factors to explain the lack of recovery of this population. From 1983 to 2012, a total of 472 beluga were found stranded. Complete necropsies were carried out on 222 beluga, including 178 adults, 25 juveniles, and 19 newborn calves. Infectious diseases, the most prevalent cause of mortality in this population, accounted for the death of one-third of all beluga (32%). Verminous pneumonia was the cause of mortality of 13 juvenile beluga (52% of juvenile beluga). A total of 39 malignant neoplasms, diagnosed in 35 beluga, caused the death of 31 beluga (20% of beluga >19 years old). Median age at diagnosis of cancer was 48 years (range, 30-61 years). Dystocia and postpartum complications were the cause of death in 18 beluga, accounting for 19% of the females >19 years old examined. The occurrence of parturition-associated complications, as well as mortality of calves <1 year old, have increased recently in this population and may be the probable cause of the recent decrease in the size of this population. One of the hypotheses proposed to explain the unusually high occurrence of some of the pathologic conditions observed in this population is chronic exposure to environmental contaminants.
authors.affiliation: Centre québécois sur la santé des animaux sauvages / Canadian Wildlife Health Cooperative, Département de sciences cliniques, Faculté de médecine vétérinaire, Université de Montréal, St Hyacinthe, Canada stephane.lair@umontreal.ca.
authors.forename: S
authors.initials: S
authors.lastname: Lair
authors.affiliation: Fisheries and Oceans Canada, Maurice Lamontagne Institute, Mont-Joli, Canada.
authors.forename: L N
authors.initials: LN
authors.lastname: Measures
authors.affiliation: Département de pathologie et microbiologie, Faculté de médecine vétérinaire, Université de Montréal, St Hyacinthe, Canada.
authors.forename: D
authors.initials: D
authors.lastname: Martineau
mesh_terms: D000818:Animals; D050643:Beluga Whale; D063366:Estuaries; D005260:Female; D008297:Male; D009369:Neoplasms / Q000453:epidemiology / Q000401:mortality / Q000473:pathology / Q000662:veterinary*; D011014:Pneumonia / Q000453:epidemiology / Q000401:mortality / Q000473:pathology / Q000662:veterinary*; D049590:Postpartum Period; D011247:Pregnancy; D011248:Pregnancy Complications / Q000453:epidemiology / Q000473:pathology / Q000662:veterinary*; D011792:Quebec / Q000453:epidemiology; D012307:Risk Factors; D014874:Water Pollutants, Chemical
chemical_list: D014874:Water Pollutants, Chemical
keywords: beluga (Delphinapterus leucas); cetacean; epizootiology; marine mammals; neoplasia; pathology; polybrominated diphenyl ethers; polychlorinated biphenyl; polycyclic aromatic hydrocarbons