Dolphins could have followed sick leader
By Emmanuelle Landais, Staff Reporter
Published: October 30, 2007, 23:03
Dubai: The mass death of more than 150 Striped Dolphins in southern Iran over the last month could be due to the herd of mammals following a sick dominant male, said a UAE-based marine expert.
In the last month a total of 152 Striped Dolphins, known for their acrobatic skills and often spotted speeding along close to bows of ships, have mysteriously washed up on Iran’s coast near Jask port.
Local media have blamed fishing malpractices and reported that locals tried to put the animals back in the water but they refused to return.
According to Saif Al Ghais, a marine biologist and biology professor at the UAE University in Al Ain, this phenomenon has never occurred in the Gulf before and could be due to a sick dolphin leading the others to mass mortality by beaching.
Pollution ruled out
“Pollution is ruled out as the cause because other marine organisms would also have been affected and as far as we know they haven’t. Whale species are scientifically known to follow a dominant male so this does happen in marine mammals,” said Al Ghais.
“If the herd follows one sick male then they will follow and die together which is why if you try to push them back they won’t go, similar to a social feeling between the animals. Another explanation is if the entire population has been affected by a disease,” he said.
Al Ghais said the dolphins washed up seemingly alive and people tried to push them back, ruling out the possibility that nets have suffocated them and corpses washed up.
Hamed Al Rahoomi, a consultant from the UAE Fishermen’s Association, said if fishing nets had anything to do with the mammals’ deaths they would be marked or have remnants on their bodies.
“If all the dolphins died together at the same time at the same place I think it is because of something they wanted to do and not because of fishing or pollution. Fishing nets would not kill so many dolphins at one time. In GCC countries trawling is illegal but if the method is still used it could have this effect,” said Al Rahoomi.
Environmentalists alarmed by ‘mass dolphin suicide’
Posted Tue Oct 30, 2007 3:16pm AEDT
The mysterious “mass suicide” of 152 dolphins washed up on Iran’s coast over the past month has alarmed environmentalists, with the blame pointed at regional fishing practices.
At the end of September, 79 Striped Dolphins were found washed up off the southern port of Jask in southern Iran, and last week another 73 dolphins were found dead in the same area.
Pictures of rows of dolphin corpses in the sand have been widely featured in Iranian newspapers, which said the dolphins had “committed suicide” – behaviour the animals have exhibited on occasion in the wild.
“The suicide of dolphins on Jask’s coast continues,” the Governmental Iran newspaper wrote on Saturday. “Locals tried to put the animals back in the water but they refused to return.”
The scale of concern over the deaths of the highly intelligent mammals has prompted Iran’s environmental protection authorities to show a dead dolphin corpse to the press to explain the “suicides”.
Mohammad Baqer Nabavi, deputy head of Iran’s environmental protection organisation in charge of marine biology, said the most likely explanation was that the dolphins drowned after becoming entangled in fishing nets rather than because of pollution.
“We did not spot pollution in the tissue of the dead dolphins a month ago,” he told reporters.
“We are basing our hypothesis for the suicide on fishing – either nets left at the bottom of the Persian Gulf or the big fishing nets that ships spread to catch different kinds of fish,” Mr Nabavi added.
“As you know, though, they are marine animals but they need to come up to surface and breathe.”
A striped dolphin, normally found in temperate and tropical waters of the world’s oceans, was frozen and shipped in from southern Iran for display and showed traces of bruising and cuts.
“We did not spot any kind of pollution in their digestive system that could have been caused from eating poisoned fish, and we also have not spotted any viruses or parasites,” he added.
But he also emphasised that the mystery had still not been solved.
He said that a committee comprised of the oil ministry, Tehran University, veterinary and shipping organisations and even the Iranian naval forces had been set up to find the cause of the problem.
Mr Nabavi said that in the next two weeks there would be some preliminary results about the cause of the dolphins’ deaths.
US nuclear-powered naval ships and other sophisticated marine craft have also been operating in the Gulf, using ultrasound tracking devices that sometimes hinder the eco-locations intrinsic in sea mammals such as dolphins.
The striped dolphin’s colour is very conspicuous and makes it relatively easy to distinguish at sea. The underside is white or pink, and one or two dark blue bands run from the bottom of the eye to the flipper.
