Repel Seals with Sound: A New Weapon to Save Endangered Scottish Salmon

Towards the Era of "Speakers from the Riverbed"?

The British tabloid Daily Mail on November 22, 2025, introduced a rather unconventional idea in an article titled "It may sound fishy, but loudspeakers could save the future of Scottish salmon."Muck Rack

The idea involves submerging underwater speakers in Scottish rivers to drive away seals that prey on salmon using sound. The concept is to emit sounds at frequencies and patterns that seals dislike near wild salmon ascending the river, making them feel "uncomfortable" and thus reducing physical collisions and predation.

At first glance, it may seem like a device from a B-grade sci-fi movie, but behind it lies an urgent sense of crisis that "wild salmon might truly disappear if things continue as they are."

How Threatened Are Scotland's Wild Salmon?

Wild Atlantic salmon are now a globally endangered species. According to analyses by UK conservation organizations, the wild salmon population across the UK has decreased by about 70% over the past 40 years, with a similar decline observed in Scotland over the past 25 years.GWCT

The latest assessment by the Scottish Government also shows a long-term decline in the return numbers of adult salmon in many rivers, with significantly fewer salmon returning compared to the past.Scottish Government

Moreover, according to the Scottish salmon industry group, the survival rate at sea, which was about 25% 30 years ago, has now dropped to around 1-5%.Salmon Scotland

There is not just one reason for this.

• Rising sea and river water temperatures due to climate change

• Water quality deterioration due to agriculture and industry

• Disruption of migration routes by dams and weirs

• And the spread of lice (sea lice) and diseases originating from marine aquacultureCitizen Space

These factors combined have made salmon a symbolic creature caught between the "climate crisis" and "industrial structure."

Seals as "Another Pressure"

Adding to this is the predation pressure from seals.

Numerous grey seals and harbor seals inhabit the Scottish coast, and salmon and trout are important food sources for them. Narrow waterways and river mouths where wild salmon return become natural "bottlenecks," making them ideal hunting grounds for seals.

In the past, there have been cases where salmon farmers and fishermen shot seals, but this practice faced strong criticism from an animal welfare perspective, and in 2020, shooting seals at Scottish salmon farms was significantly restricted.The Guardian

At the same time, the use of "Acoustic Deterrent Devices (ADDs)" to drive away seals with sound is also facing stricter regulations due to concerns about negative impacts on marine mammals like whales and dolphins.Scottish Government

In other words, from both humane and ecological conservation perspectives, it is becoming difficult to "shoot" or "drive away with loud sounds." In this context, the idea of "more targeted underwater speakers" has emerged.

"Startle Technology" — Surprising Only the Seals

An approach that has been gaining attention in recent years is called "Targeted Acoustic Startle Technology (TAST)."

This concept involves playing short sounds at random timings tailored to the auditory characteristics of seals, startling them without causing stress, and thus encouraging them to leave the area.Western CEDAR

While traditional ADDs continuously emit loud sounds to keep seals away, TAST employs a style of occasionally startling them at pinpoint moments. This approach aims to reduce the total noise level while avoiding seal habituation ("it's harmless anyway").

In Scotland, attempts to install such devices around salmon farms have already begun, with field tests underway to see if they can reduce seal damage while minimizing impacts on whales and dolphins.St Andrews Research Repository

The "underwater speakers submerged in rivers" reported this time are considered an attempt to apply this technology and concept to the migration routes of wild salmon.

Another "Sound Technology": Fighting Lice Attacking Salmon with AcuLice

Efforts to protect salmon with acoustic technology are not limited to seal countermeasures. The "AcuLice" system from Norway is gaining attention as a technology that weakens lice (salmon lice) parasitizing salmon using sound.NECON

AcuLice reportedly reduces the number of parasites by 40-60% by generating complex sound patterns, including low frequencies, underwater to suppress lice feeding and reproduction.NECON

Furthermore, unlike traditional drug administration or warm water treatment, it is a "zero-emission" solution that does not damage fish bodies or release chemicals, attracting attention from organizations like the Norwegian Food Safety Authority.NECON

In Scotland, tackling diseases like sea lice is a major challenge for wild salmon conservation, and various technological developments, such as early detection systems for lice using AI and 3D holography, are underway.Sustainable Aquaculture

The approach of "protecting salmon with sound" is beginning to be tested in a wide range of scenarios, from predator countermeasures to parasite countermeasures.

Saving with Sound or Pressuring with Sound — Concerns About "Noise Pollution of the Sea"

However, the approach of solving problems with "sound" carries many risks.

First, sound in the sea or river travels much farther than human perception. Marine mammals like whales and dolphins are highly sensitive to sound, relying on it for foraging and communication. Therefore, if acoustic devices are widely used, they could severely impact their behavior.

In fact, Scottish environmental groups and scientists have pointed out that conventional powerful ADDs could cause hearing damage or stress to dolphins and porpoises, calling for legal regulations.The Ferret

Even systems like TAST, which "reduce the number of startles and lower the volume," could raise the overall noise level of the sea if installation sites increase. If efforts to protect wild salmon end up pressuring other creatures, it would be counterproductive.

Additionally, technology that is unpleasant for humans can create friction with local communities. If anglers or kayakers feel "strange sounds when approaching the river," it could diminish its appeal as a tourist resource.

Reactions on Social Media: Welcome, Skepticism, and Self-Deprecating Humor

Reactions to the underwater speaker concept on English and Japanese social media can be broadly categorized into three types.

① "Better Than Guns" Group

"Driving seals away with sound is much more humane than shooting them."
"Even in a 'managed nature' like a zoo, it's a much better option than killing."

These voices reflect a strong aversion to seal shooting and a stance that values "non-killing management."

② "Humans Meddling with Nature Again" Group

"The root problem is climate change and excessive aquaculture, yet they're trying to cover it up with another gadget."
"Why make the sea noisier? Protecting a quiet sea is what's best for salmon, isn't it?"

These comments express a straightforward discomfort with technology-dependent "symptomatic treatment," voicing concerns about increased sea noise and impacts on other creatures.

③ "Taking It with Black Humor" Group

"Next, noise-canceling headphones for salmon?"
"Future Scottish tourist guide: 'Here is the world's first salmon river with 24-hour background music.'"

Such posts, imagining surreal future scenarios, are not hard to envision. The technology itself is interesting but carries a nuance of a "dystopian feel."

These mixed reactions of approval, disapproval, and jokes well reflect the modern dilemma of "how much technology should be introduced into nature conservation."

Reconsidering "What We Want for Wild Salmon"

The seal countermeasure using underwater speakers holds significance beyond being a mere gadget. It serves as a litmus test for how we want to preserve wild salmon.

• Is it acceptable to have a somewhat "managed nature" as long as extinction is avoided?

• Or should human intervention be minimized, leaving it to "natural selection"?

• Alternatively, is proactive human intervention necessary to take responsibility for the pressures placed on salmon by climate change and industrial activities?

In Scotland, large-scale reforestation along rivers and restoration of river shapes are underway as more "subtle" habitat improvement projects. For example, in the Dee River basin, a long-term reforestation and river restoration project has begun to lower water temperatures.The Guardian

While underwater speakers could serve as a "training wheel" for these efforts, they also risk obscuring "what should really be done."

A Hint for Japanese Readers: Look at the "River" Before Technology

In Japan, the decline of migratory fish like salmon, trout, and ayu is also a