San Diego-based researchers study dolphin choking deaths

SAN DIEGO (CNS) – Bottlenose dolphins in Florida's Indian River Lagoon are asphyxiating themselves when they try to swallow certain types of fish, the San Diego-based Hubbs-SeaWorld Research Institute reported on Tuesday.

Of 350 deaths of bottle-nosed dolphins in the lagoon over the past 15 years, 14 were caused by choking, according to a study published in the scientific journal PLOS One. No deaths of dolphins in the ocean were caused by asphyxiation during that time period, the authors found.

“This is the first study documenting a statistically significant number of dolphin deaths caused by choking,” said Megan Stolen, a scientist at the institute and the study's principal author. “This research lays a critical foundation for future study because of environmental changes and invasive species altering prey populations.”

The dolphins that died either ingested strong-spined fish whose fins had punctured and lodged in the esophagus, obstructing the airway; or ate fish attached to fishing line that wrapped around the larynx and interfered with breathing, according to the researchers.

The Indian River Lagoon is on the state's Atlantic coast, near Melbourne and Cape Canaveral. Pam Yochem, a wildlife veterinarian at Hubbs-SeaWorld Research Institute, said the research shows dolphins might have problems with fish encroaching on their habitats as ocean temperatures change.

The impact of prey availability is being reviewed, she said. The researchers said they also planned to look into whether choking was affecting other dolphin populations, and will examine other causes of deaths for the species.