Lumpfish could be the solution to controlling sea lice in ocean-based salmon farms.
Steve Eddy, director of University of Maine's Center for Cooperative Aquaculture Research, holds a juvenile lumpfish at the center's Franklin campus on August 25, 2022. Researchers are learning how to raise the native Maine fish, which eat sea lice, to help salmon farmers prevent sea lice outbreaks. Credit: Bill Trotter / BDN

With the help of a docile fish with an unusual name, researchers at the University of Maine are hoping to help salmon farmers address a problem that has plagued them for decades: sea lice.

Sea lice are a type of parasitic crustacean that can infiltrate salmon cages in the ocean. The lice latch onto salmon and harm both the salmon’s appearance and its health, reducing the value of the fish. In 2016, sea lice infestations caused the world’s supply of farmed salmon, estimated to be million of tons each year, to drop by 10 percent, according to UMaine researchers.

Scientists at the university’s Center for Cooperative Aquaculture Research in Franklin believe lumpfish, a species native to the Gulf of Maine, can help salmon growers to prevent sea lice outbreaks, and they are getting an injection of federal funding to help them continue their research.

The National Oceanic and Atmospheric Administration has promised $234,487 over three years to help fund its efforts to establish a reproductive broodstock of lumpfish for use at salmon farms.

Salmon farming has been a multi-million dollar business in Maine since the 1990s, when aquaculture firms started cultivating the popular fish in pens in the ocean for the domestic seafood market. New Brunswick based Cooke Aquaculture grows millions of pounds of salmon each year at two dozen ocean sites in Hancock and Washington counties, and at least three other companies are hoping to establish large salmon farms on land in Belfast and Bucksport, and in the waters off Mount Desert Island.

For many years, salmon farmers used chemical baths to kill the sea lice, which alarmed lobster fishermen and environmentalists, who said that the treatments harm the ocean and can kill lobsters.

The use of chemicals fell out of favor with salmon growers as sea lice developed greater resistance to the treatments. Other management methods for the persistent problem have included giving salmon warm water baths and growing mussels, which filter sea lice from the water, next to salmon cages.

UMaine researchers are now focused on lumpfish as a possible solution.

First, though, they have to figure out how to grow them reliably in captivity. Juvenile lumpfish, which are native to the Gulf of Maine, can live with salmon in the sea cages and remove lice off the other fish before they cause any significant harm.

A relatively sedentary fish that has a suction disk it uses to attach itself to rocks, lumpfish already are used at salmon farms in Norway, Scotland and eastern Canada. In the summer of 2018, CCAR researchers collected more than 150 lumpfish off MDI and since then have collected hundreds more as part of an effort to establish a domestic supply of lumpfish that salmon growers can use as part of their operations.

“Their options are really limited,” Steve Eddy, the director of CCAR and lead investigator on the project, said of the methods for preventing sea lice outbreaks. “Lumpfish will eat sea lice off the salmon.”

Having lumpfish in the salmon pens also reduces the need to handle the salmon, which can cause them stress and result in reduced production volumes, he said.

Eddy said UMaine researchers have been learning to get lumpfish to spawn and then how to grow them relatively quickly. Lumpfish are smaller than a pea when they are young, but they can grow from weighing one gram to weighing two kilograms — roughly the size of a football — in less than two years. 

The University of New Hampshire and the USDA’s National Cold Water Marine Aquaculture Center, located next to the UMaine facility in Franklin, also have been involved in the lumpfish research.

 Federal researchers involved in the project have been trying to breed lumpfish that are more comfortable at slightly warmer water temperatures, which salmon seem to prefer.

The grant from NOAA will help researchers collect wild lumpfish from more places in Maine, which can help broaden the genetic diversity of the brood stock, Eddy said. 

Further research also may help breed lumpfish that are more intent on seeking out sea lice and make them more interested in sea lice as they age. Adult lumpfish often end up eating food intended for the salmon instead of sea lice, he said.

“Some of them seem to eat more sea lice than others,” Eddy said. “They get lazy when they get older.”

If the researchers can establish a commercially viable broodstock of lumpfish in the U.S., it should help make salmon farming more productive and environmentally sustainable, Eddy said.

“We are excited and grateful that NOAA Sea Grant is helping us expand our efforts,” he said.

A news reporter in coastal Maine for more than 20 years, Bill Trotter writes about how the Atlantic Ocean and the state's iconic coastline help to shape the lives of coastal Maine residents and visitors....