On Friday, 31 March 2017, a mass stranding of 38 common dolphins was reported to have occurred along a remote stretch of coast under the protection of Addo Elephant National Park, between Sundays River Mouth and Woody Cape in Algoa Bay, Eastern Cape.
The local authority dealing with all whale, dolphin and seal strandings, the Port Elizabeth Museum at Bayworld, was alerted. A site visit on the day by South African National Parks (SANParks) and Department of Agriculture, Forestry and Fisheries (DAFF) officials ascertained that the animals most likely had been stranded four to five days earlier and were all dead.
A team of seven people, comprising members from Bayworld and the Cetacean Research Unit at the Nelson Mandela Metropolitan University (NMMU) set out from Port Elizabeth early on Saturday 1 April to respond to the stranding event. Staff and volunteers from Addo Elephant National Park provided support.
The animals were found to be spread out over a 2km stretch of coastline. There were 28 adults and 10 juveniles, of which 12 were male and 26 females. The response team was split up into three teams, each comprising an experienced marine mammal researcher and a number of interns and volunteers. Over the next two days, the teams collected basic information such as sex, length and maturity status from each individual dolphin. In addition, carcasses were dissected to obtain vital information on the cause of death of the dolphins.
Dr. Stephanie Plon, a member of the African Earth Observation Network (AEON) at NMMU, has been researching dolphin and whale health in Eastern Cape and KwaZulu-Natal waters for the past nine years and indicated that, while the animals were partially decayed, all appeared healthy and in good condition. However, multiple samples were collected from all individuals for further analysis.
Dr. Greg Hofmeyr, curator of the marine mammal research collection at Bayworld, secured tissue samples as well as skeletal material for the extensive marine mammal research collection at the museum. This data will add important information on the taxonomy of this species in South African waters.
This section of the coastline appears to be a unique spot on the southern and eastern coasts of South Africa for mass strandings, with four other such events recorded by Bayworld since 1977. However, this stranding event comprises the largest one yet. Dr. Plon and Dr. Hofmeyr regularly attend to marine mammal stranding events along the Eastern Cape coastline, each one providing a challenge. While such events are tragic for the animals concerned, they are very valuable for research on these animals.
Dolphins are at the top of the marine food chain and as such are important indicators of the health of our oceans. No obvious cause for this unusual stranding event could be determined, but no evidence of foul play was found. Further analysis may provide additional information. However, in order for the researchers to pinpoint the cause of individual stranding events it is imperative that strandings are reported as soon as possible to the local authorities so that better information can be gathered.
Members of the public are encouraged to report any marine mammal strandings (whales, dolphins, seals), dead or alive, to the Bayworld stranding hotline: 071-724 2122.