‘Isolated Incidents’: Dolphin strandings in Gqeberha spark concern, but experts urge calm

Marine mammal experts in Nelson Mandela Bay said there was no cause for alarm just yet after three dolphins washed ashore in the past two weeks.

Most recently, an adult common dolphin died shortly after becoming stranded at Denville Beach on Tuesday, 15 September, just days after two young bottlenose dolphins washed up at nearby King’s Beach. 

These incidents raised alarm bells in light of the recent mass mortality of sardines along the same stretch of coastline, due to the outbreak of the pilchard herpesvirus. However, there is no evidence suggesting any link between the incidents.

The public has also been asked to take care when encountering stranded animals, and to contact local experts rather than attempting to push ocean mammals back into the surf.

“At this stage, we don’t believe there is any cause for alarm around the stranded dolphins. However, we will continue to monitor the situation and we ask the public’s help to notify us as soon as they see any more beached animals,” said Dr Greg Hofmeyr, the curator of Bayworld’s marine mammal collection.

Being the bottlenose dolphin capital of the world, beachgoers in Nelson Mandela Bay are often treated to dolphin sightings along the beachfront. Understandably, any sighting of dolphins in distress or washing ashore also leads to major concern among residents and visitors.

The first in the series of strandings occurred early last week when a newborn bottlenose dolphin was found dead on King’s Beach.

“It is not clear if the animal was already dead when it washed ashore, or if it died on the beach. It was still fresh and showed no clear signs of what could have caused its demise,” Hofmeyr said.

On Monday afternoon, a second dolphin was found along the same stretch of beach. Hofmeyr said it was older than the previous one, but still a calf. However, it was already badly decomposed and probably died at sea days before washing up on the sand.

“The newborn’s carcass was preserved, and we plan on doing a necropsy to try to determine the cause of death. No samples were taken from the second carcass as it was already badly deteriorated.

“At the moment we are treating these as two isolated incidents. These were two very young dolphins and they were still very vulnerable. They likely became separated from their mothers, for any number of reasons, and could simply not survive on their own.”

Hofmeyr said bottlenose dolphins travelled much closer to the shore than other species, and while finding them stranded – dead or alive – may be distressing to residents, it was not uncommon or anything to be worried about at this stage.

However, a common dolphin washing ashore is a far less likely scenario, but Hofmeyr said there was still no cause for alarm just yet.

“From what we understand, this specific one became stranded and members of the public helped it back into the surf. It apparently swam in circles for a bit before beaching again. By the time our teams managed to get there the animal had unfortunately died.”

Hofmeyr explained that common dolphins occurred further off shore and seldom swam very close to the beach, but offered some likely scenarios that could have landed this one in trouble.

“Chances are that it chased some prey too close to the beach and became disoriented and could not find its way back out to sea. Another possibility is that it was separated from its pod and harassed by territorial bottlenose dolphins that drove it too close to the beach.”

He said a necropsy revealed “rake marks” along the dolphin’s one side, which were probably cuts caused by other dolphins’ teeth. The animal’s bladder also showed signs of possible infection.

None of the three dolphins showed signs that suggested their deaths could be linked to the outbreak of pilchard herpesvirus that caused thousands of sardines to wash ashore in recent weeks at beaches along Namibia, the West Coast, Southern Cape, Nelson Mandela Bay and Buffalo City.

The Department of Forestry, Fisheries and the Environment announced last week that tests confirmed pilchard herpesvirus as the most likely cause of the mass mortality, and a temporary limit on sardine fishing was imposed until surveys could confirm the extent of biomass losses and the potential impact on the environment and other species.

“There is currently nothing that links the pilchard herpesvirus outbreak to these dolphin deaths. The two young bottlenose dolphins were still sucklings and would not have ingested sardines, while we found no sardines in the older common dolphin’s intestines,” Hofmeyr said. “That being said, we don’t even know if this strain of pilchard herpesvirus is dangerous to top predators like dolphins.”

Hofmeyr said their team at Bayworld would be monitoring the coastline closely for any further strandings, and asked the public to be on the lookout for any animals in distress.

“We ask that anyone who comes across stranded animals to immediately contact our emergency hotline. They can send a picture and location of the stranded animals, and our experts can give them instructions on how to keep an eye on the animals without putting themselves or the animal in danger.”

Despite the public’s best intentions, Hofmeyr said common dolphins did not respond well to human interaction when stranded. Because they did not venture close to the shoreline, they became very stressed and easily disoriented.

The best course of action, when finding a beached dolphin, whale or seal, would be to monitor it from a distance until you could reach the team at Bayworld.

To report any beached animals, contact Hofmeyr and his team at 071 724 2122. DM