Following the Cape Farewell Expedition, MCR scientists, Anna C and Olly join the boat in Stornaway, Isle of Lewis, to complete the last few days of ship noise measurements, which were started in the English Channel in July. With four days remaining to collect as many ship noise measurements as possible, the Minch (the channel between the Isle of Lewis / Skye and the Scottish mainland) was selected as our location. The Minch is a much quieter shipping location than the Channel and the hope is that this would play to our advantage getting fewer but higher quality measurements, without the excess of background shipping noise confusing the recordings.
The field work goes very well, with perfect weather (mostly calm seas, little wind) and a slow but steady drift of vessels. Additionally, due to the great sighting conditions while waiting for the vessels to enter the study site, we were treated to copious harbour porpoise and common dolphin groups, common and grey seals, puffins, guillemots, jellyfish and even a few Minke whales. In fact, here the problem is not with excess background shipping noise, but with dolphin whistles clouding our recordings!
We obtain several good recordings of cargo and tanker vessels during close passes over the first three days of work. Additionally, we are fortunate to collaborate with the local ferry company, Caledonian Macbrayne, to get repeat recordings of some of their vessels, measuring both the port and starboard side and in variable sea conditions (as the weather deterioriates). These measurements will allow an assessment of the quality of our recordings, to quantify any differences in sound propagated from each side of a vessel and to see the effect weather has on the accuracy of our measurements – all essential for properly assessing our methodology.
Overall we have obtained over 20 useful measurements of cargo and tanker vessels in the Minch and the Channel combined. The analysis of the ship noise profiles will continue with the aim of providing data and results to the next IMO Marine Environmental Protection Committee meetings in the coming months.
