Facts and myths about permit to farm steelhead in Puget Sound

In January, the Washington Department of Fish and Wildlife (WDFW) issued a five-year permit to Cooke Aquaculture to farm all-female, triploid (sterile) rainbow trout/steelhead in Puget Sound.

These fish would be raised in Cooke’s existing facilities — where they currently raise non-native Atlantic salmon — including four pens currently operating near Rich Passage and Skagit Bay, but may later extend to three other net pens owned by Cooke.

WDFW issued an extensive justification document explaining the regulations and science behind our decision. We recommend that this document be read to best understand the justification for our decision, but we know there are many questions about the permit, why it was approved, and what it means. We’ve attempted to answer some of those questions below.

What exactly does this permit do?

This permit allows Cooke to transition from raising non-native Atlantic salmon to raising native, all-female triploid (sterile) rainbow trout/steelhead in its existing net pen facilities where the company holds valid aquatic lands leases with the Washington Department of Natural Resources.

Why did WDFW approve this permit?

The short answer: The law allows for the marine farming of native finfish, including steelhead trout. Cooke proposed to transition from farming non-native Atlantic salmon to native sterile steelhead trout. The department determined that the disease, escape, and genetic risks of farming these sterile steelhead were similar to or perhaps lower than the risks associated with farming Atlantic salmon.

The long answer: Following the escape of about 250,000 Atlantic salmon after a Cooke-operated net pen collapsed at Cypress Island in August 2017, the Washington State Legislature passed EHB 2957. This outlawed the farming of non-native species in Washington’s marine waters when the current aquatic land leases end in 2022. It did not ban all finfish net-pen farming in Washington state marine waters, and allowed for the farming of native finfish, including steelhead trout.

As a result of this legislation and the requirement that they transition away from farming non-native Atlantic salmon, Cooke in early 2019 submitted an application to farm steelhead trout.

WDFW was then required to evaluate if Cooke’s proposal to switch from Atlantic salmon to all-female sterile steelhead trout would result in “significant genetic, ecological or fish health risks … [to] naturally occurring fish and wildlife, their habitat or other existing fish rearing programs.

After scientific review, WDFW determined that raising steelhead trout in the existing net-pen facilities would carry similar or less risk than raising Atlantic salmon.

Why doesn’t WDFW just ban these pens? Aren’t net pens banned elsewhere on the West Coast?

Banning marine net pens in Washington state would require legislative action. WDFW has no authority to ban or eliminate these pens in the state. WDFW’s regulation of commercial aquaculture is also constrained by how we regulate our own and other hatcheries and marine net-pens.

Marine net pens are banned or otherwise restricted in Alaska, California, and Oregon. British Columbia has numerous net pens, but the government has announced its intention to move away from marine net pens in B.C. waters in the years ahead. A number of net pens there have recently been decommissioned.

Why did WDFW approve this application for an aquaculture company with a history of issues in the state?

WDFW is committed to maintaining the health of fish and habitat in the state. To ensure that this permit does not compromise native fish populations, WDFW is requiring that Cooke adhere to the contents of their permit proposal and to the 29 mitigating provisions included in their approved permit.

These conditions are broken down into three main categories: Operations, Escape prevention/response/reporting, and disease reporting and biosecurity.

Below is a brief outline of some of the provisions — for the full list, see the justification document.


  • The permit is specific to the rearing of only all-female triploid steelhead trout from embryos originating from Troutlodge in Bonney Lake, Washington.
  • Cooke must mark all fish with a visual indicator that unambiguously identifies commercial aquaculture fish and differentiates them from natural- or hatchery-origin fish.
  • Tissue samples must be provided to WDFW from each lot of fish to be transported to marine net-pen facilities, to conduct genetic testing on those fish.

Escape prevention, response, and reporting

  • Cooke must develop, in consultation with WDFW, DNR, Ecology, and affected treaty tribes, a Fish Escape, Prevention, Response and Report Plan.
  • Inspections of net pens will be conducted every two years by a WDFW-approved marine engineering firm to ensure structural integrity and permit compliance.
  • Any fish (minimum of one fish) observed to have escaped from a net pen must be reported within 24 hours.
  • Cooke must have engineered mooring and anchoring plans and site-specific engineered drawings stamped by a structural engineer for each net-pen facility by Jan. 1, 2021.

Pathogen reporting and biosecurity

  • Net-pen facilities must remain fallow for 42 days after fish are harvested and the last containment net is removed for cleaning and repair.
  • Broodstock (parents) of eggs/fish going to Cooke freshwater rearing facilities will be tested at a certified lab for Washington Regulated Pathogens.
  • Smolts will also be sampled and tested for pathogens prior to transfer from freshwater facilities to marine net pens.
  • Fish carcasses may not be removed from net pens and dumped in open water.
  • All disease outbreaks, unexplained mortality, and regulated, reportable, or exotic pathogen findings must be reported within 24 hours.
  • A fish health inspector must submit an annual fish-health evaluation report summarizing health inspections, tests, and the presence of any pathogens.

I heard that these fish are “mostly sterile.” What does that mean? Will they be able to reproduce with native fish populations?

Triploid (sterile) females are unable to reproduce. Sterile lots of fish are most frequently produced by inducing triploidy — that is, producing fish with three sets of chromosomes rather than the normal two. Cooke’s permit is contingent on raising only all-female, triploid trout.

Triploidy can be induced by shocking newly fertilized eggs with heat or pressure. These methods have a success rate approaching — but not achieving — 100 percent.

Based on WDFW’s analysis, a stock of 1 million triploid fish in a net pen may contain approximately 2,000 fertile fish. In the event of an escape like the one that happened at Cypress Island in 2017, we estimate that between 63 and 316 fertile fish might escape and survive to sexual maturity.

These domesticated fish would then need to migrate into a steelhead spawning river, without homing or cues to enter a specific river, at the correct time of year, dig redds, and attract mates. Given these requirements, the low number of fish, and relative unlikelihood of an escape like the one in 2017, we consider the risk of these farmed fish adversely affecting the genetic structure of wild steelhead in Washington to be low.

Why didn’t WDFW require an Environmental Impact Statement to raise these fish?

We were tasked with determining if Cooke’s proposed action to switch from Atlantic salmon to all-female triploid steelhead was “likely to have a probable significant adverse environmental impact” under the State Environmental Policy Act (SEPA).

In October, WDFW posted a SEPA “mitigated determination of non-significance” (MDNS) analyzing the potential genetic and environmental impacts of Cooke’s proposal to transition from farming Atlantic salmon to farming steelhead in several of the company’s existing facilities.

A determination of non-significance is made when it is determined an action will not have a “significant” adverse environmental impact, or the impact would be less than moderate or average. An MDNS is made when mitigating provisions (like those listed above) are required to minimize any potential environmental impacts. An MDNS does not require an Environmental Impact Statement.

Where can I get more information?

You can find much more information about the application and the permit process at WDFW’s SEPA webpage, where you can find our justification for the MDNS, details about Cooke’s proposed action, and the original 1990 EIS that evaluated environmental impacts of fish farming in Puget Sound, among other materials.



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The Washington Department of Fish and Wildlife

The Washington Department of Fish and Wildlife


The Washington Department of Fish and Wildlife is dedicated to preserving, protecting and perpetuating the state’s fish and wildlife resources.