A Wildlife Disease Investigation Case from the Wildlife Disease Association Newsletter
October 2012 Issue
By Patricia Mendoza, Wildlife Conservation Society, Perú.
Dolphin mortality was reported along the Northern Peruvian coast, from Piura to La Libertad regions [click links to view location on Geonames], since January 2012. Species affected were long-beaked common dolphin (Delphinus capensis) and black or Burmeister’s porpoise (Phocoena spinipinnis).
In April, the Peruvian Institute of the Sea (IMARPE) counted 877 dolphins carcasses along 178km of coast, 78% of which were in advanced decomposition, resulting in limited sample collection. The dieoffs have sparked widespread speculation about the causes, but none have been scientifically confirmed.
Post-mortem analysis of 42 animals showed no signs of starvation, respiratory, digestive or neurological disease. While dolphin morbillivirus was suggested as a potential cause, there was no evidence of lessions indicative of morbillivirus infection in carcasses examined during this mortality event. Laboratory analyses of samples obtained from two animals resulted negative to PCR for Morbillivirus, Leptospirosis and Brucellosis, as well as heavy metals (copper, lead and cadmium) and pesticides (carbamates and organochlorines) by thin-layer chromatography.
Later this year avian die-offs were also recorded along Peru’s northern coast. Pelicans (Pelecanus thagus) were the most affected species, followed by the Peruvian booby (Sula variegata) and cormorants (Phalacrocorax bouganvillii).
The National Animal Health Service (SENASA at the Ministry of Agriculture) collected and analyzed 4 pelican and 2 booby carcasses and reported the finding of Pasteurella multocida. All animals sampled were negative for Avian Influenza, Newcastle Disease and Avian Mycoplasma. A large pelican die-off event occurred in 1997 following El Niño which caused declines of anchovies, a primary food source for pelicans. Starvation is also suspected in this year’s seabird dieoffs, with air and sea temperature warming effects implicated this past year from El Niño.
As a result of these events, the Directorate of Biodiversity (Ministry of Environment) is currently working to establish a Peruvian Stranding Network which will include representatives of the Peruvian government, universities, and NGO’s.
Source: WDA Newsletter – October 2012 Issue [pdf]