How net pens support sustainable fisheries

Net pens used to release native species of salmon have provided sustainable fisheries in western Washington for decades. An example is the Peale Passage facility in deep South Sound, operated jointly by the Squaxin Island Tribe and the state Department of Fish and Wildlife.

Every winter as many as 1.8 million coho are trucked from state hatcheries around the region and transported by barge to a series of floating net pens. The Squaxin Tribe manages the day-to-day operations of the net pens between Harstine and Squaxin islands.

In addition to providing fisheries, the special nature of net pen facilities allows the tribe to craft fisheries to protect wild spawning coho populations.

“Those fish that we released from the net pens tend to concentrate near Squaxin Island and the surrounding islands when they return, so that’s where we fish,” said Joe Peters, fisheries harvest manager for the Squaxin Island Tribe.

Most salmon return to the stream where they were born, but because net pen fish are released directly into Puget Sound, their homing instincts bring them back to the pens.

The Squaxin Island Tribe fishes for fall coho in deep South Sound, avoiding bays and inlets where wild coho congregate. More than 95 percent of the tribe’s commercial fishery are hatchery fish, according to catch samples.

“The reason we manage our fishery the way we do, avoiding terminal areas, is to protect wild runs of coho while harvesting hatchery fish,” Peters said.

Net pen coho also contribute to sport fisheries in Puget Sound. “Thousands of these fish are caught by sports fishermen each year,” Peters said.

The tribe consistently explores ways to improve management of the coho net pens.

To narrow down where bottlenecks to coho productivity are in Puget Sound, the tribe has experimented with releasing small groups of coho north of the Tacoma Narrows and at the entrance of the Strait of Juan de Fuca.

Tribal hatchery managers also experiment with release timings to see if survival improves. Indicators suggest that predation by marine mammals, particularly harbor seals, adversely affects the survival of both net pen and wild coho.

“Managing operations like these means we have to constantly learn more about how these fish survive and the conditions we’re putting them in,” said Andy Whitener, natural resources director for the tribe. “Once these coho are released, they depend on the same habitat that all other salmon do.”

The Squaxin Island Tribe maintains the day-to-day operations of the net pen facility in deep South Sound. Photo: E. O’Connell.