Young dolphin that had just learned to live without its mother found dead on New Hampshire shore

A young dolphin belonging to a species that typically resides in the deep waters of the tropics was found dead on a beach in New Hampshire. Rescuers said the dolphin was so young that it had only recently weaned from nursing from its mother.

The animal was a striped dolphin, Stenella coeruleoalba, and was found on July 14. According to NOAA, striped dolphins "are among the most abundant and widespread dolphins in the world," but usually live in ocean waters in tropical to temperate regions. In the U.S., they are typically found along the West Coast, but they are known to go beyond their normal ranges. 

The Seacoast Science Center's Marine Mammal Rescue group said the animals "are not considered resident species" of New England, although they will "occasionally" be seen along the New Hampshire coast in the summer. Seeing them, however, is "uncommon." 

"Since we began responding in 2014, our rescue team has never before seen this species of dolphin," the group said. "The striped dolphin was a female weanling (newly independent from its mother) that stranded freshly deceased on Hampton Beach."

Striped dolphins typically nurse their young between a year and 18 months as their calves learn how to fish and survive on their own, meaning that the young dolphin found on the beach was likely around that age, if not much older. 

The cause of the dolphin's death is uncertain.

"Although the dolphin had no visible external wounds initially, seagulls had unfortunately scavenged its head between the time of the report and our response," responders said. "Our team collected on-site swabs for disease surveillance, and transported the dolphin immediately to New Hampshire Veterinary Diagnostic Laboratory for a necropsy to help determine the cause of death."

Striped dolphins can generally live up to 58 years and don't reach maturity until they are at least 5 years old. Although the species is not considered endangered, it does face threats from humans, mostly through entanglements. NOAA says that the animals can easily become entangled or captured in commercial fishing gear.

Pollution is also a risk, as environmental toxins and contaminants weaken the species' immunity, NOAA says. More than 1,000 of the animals died in the Mediterranean Sea in the early 1900s due to this, after the highly contagious and lethal morbillivirus epizootic swept across the species. It's believed to have been triggered by pollution and fewer available prey, the agency says.

In:
• New Hampshire
• Oceans
• Dolphin
• Animal Rescue