Four Million Dead Salmon Is Built Into The Model

In 2025, at least four million salmon died prematurely inside Tasmanian fish farms.

Not at slaughter.

Not as part of production.

Before any of that.

Four million individuals bred into captivity simply died in their enclosures as ocean temperatures rose. In December alone, more than 40 tonnes were dying every single day. The water had become too warm, too oxygen-poor, too biologically unstable to keep them alive. Researchers now say that parts of south-eastern Tasmania are no longer fit for salmon farming at all. And still, there has been no regulatory action.

Leave a dog in a hot car and you may face prosecution.

Breed four million fishes into existence and allow them to die en masse inside your production system and the political response is silence. Because this wasn’t a failure of aquaculture. It was aquaculture functioning normally.

Farming Predators Requires Killing The Ocean

Salmon are not herbivores. They are predators.

To farm them at scale, they must be fed other animals. And not occasionally. Systematically. Every day. For their entire lives.

Carnivorous aquaculture depends on fishmeal and fish oil derived from wild-caught forage fishes like anchovies, sardines, herring, and mackerel. These are small, schooling individuals who occupy a foundational role in marine ecosystems, transferring energy from plankton up the food chain to larger fishes, seabirds, and marine mammals.

Remove them in sufficient quantities and entire ecosystems begin to unravel.

This is not theoretical. European aquaculture already focuses heavily on high-value carnivorous species like Atlantic salmon, seabass, and seabream that require nutrient-dense, animal-based feed.

The result is a second, largely invisible kill chain behind every farmed salmon fillet.

Each year, an estimated 500 to 1,100 billion wild fishes are captured and killed to produce feed for farmed aquatic animals .

Reduced into pellets to be fed to other captive animals who are themselves destined for slaughter.

This is not food production.

It is trophic laundering.

The Efficiency Myth

Aquaculture is often presented as the solution to overfishing. A way to reduce pressure on wild populations by farming aquatic animals instead.

But farming carnivores does not reduce extraction. It multiplies it.

In Europe, production of the top carnivorous aquaculture species is projected to increase by 30% by 2040. Meeting this demand will require up to 2.5 million tonnes of wild-caught forage fish every year.

That is equivalent to between 83 and 192 billion individual wild fishes annually.

A 70% increase in animals taken from the ocean not to feed people, but to feed farmed predators.

Meanwhile, mortality inside aquaculture systems remains routine. Farmed fishes are kept in crowded enclosures that restrict movement and elevate stress, disease transmission, and injury. Mortality rates in some commonly farmed species already range from 15% to 80% before slaughter .

The four million salmon who died in Tasmania were not an anomaly.

They were inventory loss.

Climate Change Is Not A Bug In The System

Scientific studies have shown that Atlantic salmon begin to suffer physiological breakdown as water temperatures approach 18°C. Oxygen availability drops. Appetite declines. Disease vulnerability increases. Organ damage follows.

These are not unknown risks. They are predictable outcomes in a warming ocean.

And yet, aquaculture continues to expand into regions increasingly affected by marine heatwaves.

Why?

Because the industry is not optimised for ecological stability. It is optimised for throughput.

Even land-based recirculating aquaculture systems do not resolve this contradiction. These facilities require dramatically higher energy inputs, sometimes emitting between two and thirteen times more carbon dioxide per kilogram of product than conventional sea-pen systems .

Farm them in the ocean and they die from warming seas.

Farm them on land and emissions accelerate the warming.

Either way, the system feeds itself.

Beyond Tasmania

Tasmania is not the exception. It is the preview.

Since 1985, seventy-eight new aquatic species have been introduced into European aquaculture. Around 70% of them depend on animal-based feed.

New proposals now aim to farm even more cognitively complex predators such as octopuses. One planned facility in Spain alone could require up to seven billion wild-caught fishes per year as feed if production expands as projected.

The logic remains unchanged:

Kill small individuals to farm larger ones.

Collapse ecosystems to produce luxury goods.

Scale mortality in the name of efficiency.

Four Million Dead Is A Warning

When four million captive salmon die in a single year because the water is too warm to sustain them, the appropriate response is not to debate fines.

It is to ask why a system that depends on warming oceans, collapsing food webs, and billions of wild animals killed for feed is still being framed as a solution.

Aquaculture does not replace fishing. It industrialises it.

And Tasmania is what happens when the ocean begins to push back.