Death of dolphin remains a mystery

 

WHILE most of Ndlambe settled in for an exciting New Year’s celebration, two dolphins were spotted swimming up the Busman’s River, but only one made it back out to the ocean – the other was found washed up dead on the river bank two days later.

OCEAN MAMMALS: The body of a bottlenose dolphin was found on the banks of the Bushman’s River on December 31, but the body was decayed and cause of death could not be determined

On December 31, Bayworld marine mammal’s curator Dr Greg Hofmeyr was contacted by Ndlambe Municipality’s conservation officer Willem Nel who reported there were dolphins in the Bushman’s River. By the end of the day it was assumed they had swum back out to sea.

However, two days later, on the evening of January 2, a dead dolphin was found on the banks of the river.

“It is possible that it is one of the previous two animals,” commented Hofmeyr.

“I drove through on the morning of the third to collect the animal, assisted by local resident Bill Northrop and friends. I took it back to Bayworld for a necropsy, which was conducted that same day by myself and Stephanie Ploen, a researcher at NMMU, together with Isa Callealta, one of her students.”

With the body in a state of decay due to the hot weather the team could not collect specimens for pathology.

“We were able to establish that it was an adult female and may have given birth in the last six months, but it was no longer lactating,” said Hofmeyr. “It had substantial bruising both above and below the head, but the reason for this could not be established and so cause of death could not be determined.”

A few days earlier, on Christmas Eve (December 24), big swells forced seal pups from their birthing place in Algoa Bay, washing them up on the beach in Kleinemonde. The local colony of Cape fur seals breeds on Black Rocks in the Bird Island Group in the bay. Pups are born in November and December and, although their bodies are adapted to spending their lives in the ocean, they are not very good swimmers in the first few months, usually the end of February.

The maximum height of Black Rocks is 4m, so if there is a storm with big swells, pups may get washed off the rocks and end up on the mainland.

According to Hofmeyr this happens every few years, and has been recorded for more than 10 years.

“We have a plan in place to respond to such an event. In fact, Bayworld, working together with other organisations such as SANParks and assisted by various volunteers have been responding to these events for at least 30 years,” said Hofmeyr.

The storm swells predicted for December were not as big as predicted, and the maximum coincided with neap tide and low tide. Otherwise, hundreds of pups could have been washed off, as has happened in the past.

In the event, only eight pups were collected, mostly from Cannon Rocks, and primarily by local resident Verona Veltman and her team. Lifts were arranged for them at short notice to Bayworld in Port Elizabeth where they were housed and looked after by Cherie Lawrence and others from the Oceanarium team.

While SANParks was due to take them back to Black Rocks on a resupply trip to Bird Island, a full cargo made this difficult. NSRI Port Elizabeth station commander Ian Grey therefore volunteered a crew, using the trip as a training exercise.

“Sadly, one of the pups died on the night before the release. On December 31, an NSRI crew lead by Mike Wilson, and with me on-board, took the pups to Black Rocks where they were placed ashore, each had plastic flipper tags that will allow scientists to follow their survival over the months that follow,” Hofmeyr said.

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