The Missing Notes: The Sound of Biodiversity Loss, Hebrides Redacted

Dr Matthew Agarwala is using sound to convey the enormity of biodiversity loss – and help draw attention to what must be done to help species recover.

Hebrides Redacted score with notes scrubbed out to reflect declining Humpback Whale population. Image credit:

In collaboration with composer Dr Ewan Campbell they have linked a piece of classical music: Mendelssohn’s ‘Hebrides Overture’, with the loss of an iconic species: the North Atlantic Humpback Whale.

The 30,000 notes in the original music score approximate to the number of Humpback Whales there were in the sea in 1829, when the piece was written. But then extensive commercial whaling began to cause a dramatic decline in the whale population – and by 1920, two thirds of all Humpback Whales were gone.

Campbell divided Mendelssohn’s score into decades, then scrubbed out notes in proportion to the decline of the whale population as the music – and time – progresses. The resulting piece, ‘Hebrides Redacted’, has proved to be a dramatically simple way for audiences to grasp the enormity of biodiversity loss over time.

A short film about the music, and its impact on live audiences, was released online on Friday 14th October, 2022 as part of the Cambridge Zero Climate Change Festival.

The orchestra performs ‘Hebrides Redacted’ at the 2022 Wilderness Festival, UK Image credit: Tom Besley

The music was performed by the 38-piece Wilderness Orchestra at this year’s August Wilderness Festival in Oxfordshire, conducted by Campbell and narrated by Agarwala. The audience response was overwhelmingly positive – and the piece received a standing ovation.

Dr Ewan Campbell who is Director of Music at Churchill College and Murray Edwards College, Cambridge, commented:

“It really was an uninitiated audience at the Wilderness Festival – people were there for a good time, not to be told that the world is falling apart through the medium of music from the 19th century. But somehow it worked.”

Hebrides Redacted doesn’t just fizzle out at the end. The duo also want to draw attention to the policies that would be needed to help Humpback Whale populations recover – so the last part of the piece looks into the future, allowing an optimistic 8% rise in whale population every decade.

Dr Matthew Agarwala, explained:

“Over the past century we have seen nearly a million species pushed to the brink of extinction – nature is going quiet.

“Researchers – including me – have been sounding the alarm about the consequences of biodiversity loss for a long time, but the message isn’t landing. Music is visceral and emotional, and grabs people’s attention in ways that scientific papers just can’t.

“We can see when the oceans are better managed, whale populations can start to rebound.”

Dr Campbell continued:

“At its nadir, the score is thin and fragmented, with isolated notes reaching for a tune that is only partially present. But even in the face of devastating destruction, nature is resilient and always beautiful, and so even when two-thirds of the music is absent there’s still a delicate beauty, though a pale imitation of its once dramatic glory.

“Redaction is a word normally associated with censorship, and silencing history. I find it really apt for this piece of music – we’re showing how human activities have silenced nature.”

Inspired by his 1829 trip to a sea cave – Fingal’s Cave – in Scotland’s Inner Hebrides, Mendelssohn’s original music captures the beauty, power, and vitality of the sea just before the introduction of mechanised industrial fishing.

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