The local waters of the Clyde are believed to host among the highest densities of porpoises in Europe.
That is the scientific assessment of David Nairn of the Clyde Mammals Group, who believes his investigative findings could change the environmental outlook towards the Clyde in future.
Speaking at a recent Fairlie Community Council meeting, David said: “We have a 40 foot yacht, and been surveying a stretch of some 5000 miles of the Clyde, and what is becoming clear, is that the Clyde has probably the highest density of porpoises in Europe.
“We have used a hydrophone since June which measures the amount of porpoises in the Clyde by listening to them. Porpoises squeak at a very high frequency at 150Khz, away above our hearing range, and it is picked up on the hydrophone with a clicking noise, and with it, we can localise. Up on the surface, if you see two porpoise, and then they are up and away and they are gone. But what we are finding is that you are only seeing 10-15% of what is actually there, and we can localise where the porpoises are and making good scientific counts. We have split the Clyde into different survey blocks for statistical analysis which is recognised by the sea mammal research unit at St Andrew’s University.
“Porpoises are a European protected species, and there are various man made pressures on the Clyde, and we can use these findings as a tool to help improve the environment.”
Hotspot areas include the Tan between Cumbrae and Wee Cumbrae, and Kilbrannan Sound.”
He added that the Clyde Mammal Group was also collecting widespread data on marine wildlife including dolphins, minke whales, fishing materials such as lobster pots, and sea litter, and working closely with the Field Studies Council in Millport.
David explained that through their analysis it could be gauged that there were high aggregates of porpoises in certain areas, and joked: “They seem to be meeting up and having porpoise parties on the Clyde!”
Analysis so far shows that there is an average of 0.65 porpoises per kilometre in the Clyde, in the hydrophone, which David nicknames ‘the porp-o-meter’, but in some high intensity areas having many as 2 porpoises per km. The calving period is in June and July, and David stated that there are more porpoises than anywhere in Scotland, even the Hebrides. “It’s fantastic news,” said David.
The Trust obtained funds from the North Ayrshire Ventures Trust to purchase the state of the art hydrophone equipment from the sea mammal research unit.