Fish that keep salmon clean and healthy are being wiped out
What’s good for farmed salmon may not be for natural ecosystems.
Small fish called wrasse painlessly peck sea lice from the skin of farmed salmon, enabling salmon farmers rely less on powerful pesticides that can harm other marine life. But there’s a catch: the wrasse are fished from the wild, and researchers have now found evidence that the practice may be depleting natural populations, with unforeseeable effects on marine ecosystems.
A team from Norway discovered a decline in wild wrasse populations after comparing catch rates at four marine protected areas – where fishing is banned – and at four regions where fishing is allowed. The sampling sites were all along the Skagerrak coast of southern Norway, a region where wrasse have been caught and shipped to salmon farmers for decades.