Predators zoom in on lice-infested salmon
Parasite picked up near fish farms may harm wild juveniles in unexpected ways
CHICAGO — Young lice-infested wild salmon not only bear the burden of a parasite load, but they are also more likely to get snapped up by predators than their clean schoolmates, new research shows.
![](https://i0.wp.com/www.sciencenews.org/wp-content/uploads/2009/02/9807.jpg?resize=1024%2C683&ssl=1)
The research, presented February 15 at the meeting of the American Association for the Advancement of Science, adds to a growing body of evidence that aquaculture, which ideally would take pressure off wild fish stocks, may harm some wild populations in unexpected ways. Scientists are still untangling the web of interactions between farmed and wild fish — a web that includes parasites, antibiotics, feed fish and the humans who scarf down more than 9 million metric tons of farmed fish every year.
When juvenile, 1-inch–long pink and chum salmon swim down the rivers of the Pacific Northwest toward the open sea, many pass aquaculture pens that dot coastal inlets. Normally, there is little overlap of adult and juvenile habitats — the young and old fish travel in different circles — and most fish don’t pick up parasites such as sea lice until they are adults. But when the wild juveniles swim through fish farm territory, the sea lice that are prevalent in the close quarters of aquaculture pens can glom onto the juveniles.