Listening for Conservation
Many of us have little comprehension of how noisy the aquatic world is, you’d be forgiven for assuming it’s a peaceful environment…it’s anything but! Our seas and oceans are a cacophony of sound and getting increasingly noisier, as human activity intensifies the soundscape.
Before the Industrial Revolution, sound waves in the marine environment would have been naturally produced; by living creatures and through environmental and geological processes. Fast forward a couple hundred years and the seas are full of man-made, or anthropogenic, noise. From the hum of a boat’s engine to the intense blasts of sound produced by military sonar, human activity has a significant impact on the underwater soundscape and the animals which live in our seas.
THE IMPORTANCE OF SOUND
Sound is a fundamental component of marine life. Whales, dolphins, and porpoises – collectively known as cetaceans – have highly developed auditory abilities. This sense is vital for all aspects of their life: communication, navigation, foraging and social interactions. From the rapid click of a porpoise hunting to the beautiful singing of the humpback whale, cetaceans utilise sound for a range of purposes. They have evolved incredible biological sonar, allowing some species to exploit the most hostile environments on Earth, with deep divers hunting in the pitch black of the midnight zone. The intensifying marine soundscape has an impact on these animals; from inducing stress and creating disturbance to, tragically, causing injury and even death.
ACOUSTIC MONITORING
We have been monitoring the underwater soundscape off the west coast of Scotland for over two decades. During expeditions on board our research vessel, Silurian, underwater sounds are recorded using a towed hydrophone (imagine an underwater microphone). This acoustic monitoring is a unique element of the work citizen scientists undertake during an expedition. HWDT is a pioneer in the field of underwater acoustic monitoring in the UK, with the first acoustic recording collected from Silurian back in 2002. Thanks to everyone who has joined an expedition over the past two decades, a colossal data set of acoustic recordings has been built. The sum of the audio files is more than 9,000 hours; the equivalent of listening to the radio continuously for a year!
The hydrophone coiled on deck, ready to be deployed to gather acoustic recordings
CONSERVATION IMPACTS
Acoustic monitoring provides an accurate and consistent way to monitor cetaceans, which can be tricky to spot in poor sea conditions. If the vocalisation signature of a species is understood, software can be developed to highlight each time a noise with that signature is detected. This method is particularly useful for monitoring the harbour porpoise – the smallest cetacean found in the Hebrides; shy, elusive, and hard to spot in inclement weather. From the acoustic data gathered by you, we were able to evidence that the Hebrides has one the highest densities of harbour porpoise in Europe. This resulted in one the largest Special Area of Conservation (SAC) for the species being designated off Scotland’s west coast.
Acoustic data collection can also preserve our natural history. HWDT hold the only known recordings of the West Coast Community of killer whales, a unique and functionally extinct population found only in UK and Irish waters. Earlier this year, the British Library archived these recordings into their acoustic library of extinct species and lost human languages, preserving these precious recordings for future generations.
HOW CAN I GET INVOLVED?
You can be part of this important work to gather vital acoustic data off Scotland’s west coast, contributing to a long-term monitoring programme which is having a positive impact on the conservation of cetaceans. Anyone can participate in an expedition as full training will be provided by our passionate, approachable and knowledgeable crew. There are a limited number of spaces available on our 2024 expeditions, so book now to join the adventure this field season.