Dubai The discovery of three dolphin carcasses at separate locations along the Dubai coastline in recent weeks has raised red flags with environmental marine experts.
No cause of death in all three specimens has been confirmed and marine scientists are sifting through a long list of possible causes to determine if the isolated dolphin incidents within days of each other share any possible links.
Laurence Vanneyre, senior marine project manager at Emirates Marine Environmental Group (EMEG), told Gulf News it was nearly impossible to determine the precise cause of death without full autopsies on the animals.
Basic physical examinations of the dolphin remains conducted by EMEG staff showed no obvious signs of injuries such as slashes from a boat propeller strike or collision, she said.
"Three dead specimens in one week is not enough to qualify as a mass stranding which can be caused for example by the effects of sound pollution or disorientation by disease," said Vanneyre.
Dolphins can die from a variety of factors ranging from "old age, entanglement in fishing nets, pollution due to oil spills or other sources of pollution such as heavy metals, PCBs and plastic bags which are not toxic but can be ingested and cause death".
Other causes of dolphin deaths include "bacteria, viruses, pathogenic fungi or parasite worms. Around 30 per cent of marine mammal deaths are due to bacterial infection," she said.
Investigations continue, meanwhile, into the first sighting of a dead Indo-Pacific bottlenose dolphin, 1.91 metres in length, discovered in the Jebel Ali area on March 15. Tissue, skin and flesh samples were taken by EMEG staff for further DNA analysis.
"The shape and number of teeth allowed us to determine that it was a young common bottlenose dolphin, the most common dolphin species in the UAE. No marks were visible that could indicate the cause of death," Vann Eyre said.
Five days later, an EMEG team on patrol uncovered the second deceased dolphin at Ghantoot and the animal was identified as a 1.90-metre long spinner dolphin, a variety well known "for its acrobatics and aerial displaying behaviours."
Vanneyre said its fins were "already decomposed; it had probably been in the water for a few days before it was washed up on the shore."
Experts with EMEG were surprised yet again two days later when a third dolphin washed up with the spray on the shores of Palm Jumeirah where a hotel manager quickly called in marine experts.
"We identified this as a large specimen — 2.6 metres long — of the Indo-Pacific bottlenose dolphin. No mark of damage caused by a boat collision boat propeller or entanglement was visible, so it was determined that the dolphin had probably died of old age," she said.
To get a better grasp on any future dolphins washed up on shore in Dubai, EMEG staff are seeking a qualified veterinarian to "perform full autopsies… to help identify cause of death when it is not obvious from the body," said Vanneyre.
Given the lack of data on some bottlenosed species of dolphins, the agency said it is now working to establish a database to help fill in some of the blanks.
Vanneyre said EMEG staff members were now "assembling a database of all of the dead stranded marine mammals in the UAE that we are aware of."