Farmed salmon secretly eat wild fish

Most of the salmon you eat has never actually seen the ocean floor, but it might be responsible for a microscopic massacre happening miles away. Those neat, orange fillets at the grocery store started as residents of massive underwater cages where "natural" is a relative term.

These floating pens turn into biological pressure cookers. Because hundreds of thousands of fish are packed into tight quarters, a tiny parasite called a sea louse finds a feast it could never encounter in the wild. On a lone wild salmon, a few lice are an itch; in a farm, they multiply into a cloud of billions.

This is where the math gets lethal. When wild baby salmon swim past these farms on their way to the ocean, they have to navigate through a literal soup of parasites. A juvenile salmon is often smaller than a credit card, and it only takes two or three lice to eat through its skin and kill it.

It isn't just the lice doing the damage. To keep these fish alive in such crowded conditions, farmers often use chemical baths and antibiotics that don't stay inside the pens. These chemicals drift into the surrounding water, potentially harming or killing local shrimp and lobsters in the area.

If a storm breaks a pen open, the chaos deepens. Thousands of farmed salmon escape and begin breeding with wild survivors. These "domesticated" fish are bred to grow fast and eat pellet food, not to survive a winter or outrun a bear. When they interbreed, they pass on "lazy" genes that strip wild populations of the very instincts they need to stay alive.

The strangest part is the color of the meat itself. Wild salmon get their signature pink hue from eating krill, but farmed salmon would naturally stay a dull, unappetizing gray. To make them look "correct" for the supermarket, farmers add synthetic pigments to their feed.

Without those chemical dyes, your salmon dinner would look more like a piece of wet cardboard. We are essentially painting the fish to match a version of nature that the farms themselves are helping to erase.