Visiting dolphins ‘likely pollution contaminated’
DOLPHINS found around Guernsey are likely to be contaminated with pollutants, after research showed high levels in those from Normandy waters.
The paper published in Scientific Reports found levels of pollutants in bottlenose dolphins, Tursiops truncatus, along the Normandy coast, to be among the highest reported for cetaceans (whales, dolphins and porpoises).
Liz Sweet from the Guernsey DolFin project said dolphins seen in Guernsey could also be affected by the pollution.
‘The dolphins in our waters are coming from somewhere and it is highly possible they are coming from Normandy, but we aren’t far enough in our analysis to state that conclusively yet.
‘The more photos people send in to us, the more comprehensive our ID database can be and the more we can say.’
Ms Sweet said the dolphins could be coming to Guernsey due to high numbers in Normandy or because they are following food.
‘The paper notes the Normandy dolphins are increasingly threatened by pollutants, noise pollution – particularly construction noise – disruption from tourism activity and bycatch. So it’s possible they’re coming to us to escape those threats,’ she said.
The study looked at levels of persistent organic pollutants, POPs, in the blubber, and mercury in the skin of bottlenose dolphins in the Normanno-Breton Gulf.
This area has one of the largest identified populations of bottlenoses in Europe.
Authors said they strongly recommended the gulf be a special area of conservation candidate because it contains the last large European population of bottlenose dolphins.
‘The level of pollutants in the Normandy population is on par with very polluted areas off Brazil.
‘Portuguese dolphins have half the pollution or less and this means they are living in cleaner water.
‘Portugal has done a lot in establishing marine protected areas,’ said Ms Sweet.
She said a special area of conservation would not only benefit dolphins but fish and humans too.
‘Pollutants concentrate as you go up the food chain, so apex predators like dolphins, whales, tuna, sharks and so on will have higher levels of pollutants than animals lower down. This is because you are what you eat.
‘When dolphins eat they are exposed to whatever their food was exposed to in the water.
‘If they are in industrial areas, or areas where pollutants are concentrated, they will be more polluted as a result.’
Ms Sweet said it would be interesting to know if the 82 dolphins sampled by the study were from all three pods along that coast.
She said the wide range of where dolphins were sampled suggested all three Normandy pods were affected.
‘Even if our dolphins are not coming from Normandy they will probably be contaminated with PCBs [polychlorinated biphenyls – industrial chemicals] as they stay in the environment for ages.’
n The DolFin Project advises that islanders can do their bit for dolphins visiting the Bailiwick by keeping a safe distance from them while out at sea. If they come to the boat that is all right but they should not be crowded or followed if they try to swim away.
