Antibiotics: An extreme solution best in moderation

The use of antibiotics to control disease in farmed animals, whether on land or at sea, has always been a somewhat controversial practice. Evidence of antibiotic-resistant bacteria in humans is emerging, and many worry that overuse in livestock production will not only breed resistant bacteria in the animals, but also allow bacteria to threaten human health through consumption of the product.

The issue came to a head last summer, when Chile’s National Fisheries and Aquaculture Service produced a report showing that farmed salmon and trout operations in Chile used more than 993,000 pounds of antibiotics in 2013, compared to Norway, which produced more fish but employed only a fraction of the drugs. John Forster, a scientist who has worked in aquaculture for 50 years and has advised the Global Aquaculture Alliance on the group’s certification standards, said the mistake salmon farmers are making is believing the same practices used to treat and prevent disease for land-based livestock will work in salmon farming.

The amounts reported last summer, Forster said, might not be so crazy if farmers were raising chickens or other animals, but “it’s a lot for salmon.”

The main push for their use in Chile, he said, comes from Salmonid Rickettsial Septicaemia (SRS), a disease that threatens some salmon stocks, particularly coho salmon, which is a common species grown in Chile. Antibiotics can curb the disease, Forster said, and are legal to use in Chile.

“They’re not using anything off-label as it were, but the amount is excessive,” he said.

Antibiotics, Forster said, should never be used as a long-term solution to a problem. If the farmers want to fight SRS, he said, they need to find a vaccine for the disease, which researchers in Chile are “intensively” working on right now.

Once that happens, he said, use of antibiotics will drop dramatically there. Elsewhere in the world, he said, there is less pressure to use them, not to mention strict rules about when and how and even who can order their use.

“In most of the countries producing salmon it’s working pretty well,” he said.