Bull trout help examine the health of the Dungeness River

The Jamestown S’Klallam Tribe and its state co-manager, Washington Department of Fish and Wildlife (WDFW), hope learning about the condition of the Dungeness River bull trout population also will inform them about the health of the river.

While the tribe does not fish for bull trout, it can have a major impact on species the tribe does harvest, as bull trout prey heavily on juvenile salmon and steelhead.

“Bull trout are a unique species and exhibit a number of complex life history strategies,” said Chris Burns, a Jamestown S’Klallam Tribe natural resources technician. “Very little is known about them in the Dungeness, but they’re part of the circle of life in the river. Bull trout depend on cold, clear water for survival, and without it, they don’t exist. They also depend on healthy salmon runs for food.”

“Bull trout are listed as threatened under the Endangered Species Act, and therefore of great interest to co-managers,” said Kathryn Sutton, lead fish biologist for WDFW in the Strait of Juan de Fuca. “A lot of collaborative work has been done in the Dungeness the last couple of years on numerous projects, and these collaborations are integral in making these projects successful.”

The tribe, WDFW, U.S. Fish and Wildlife Service, National Oceanic and Atmospheric Administration, U.S. Forest Service, and a private environmental contractor have been using several tools to gather genetic and population data on the river’s bull trout population. These include in-river netting and angling, and a large-scale snorkel survey that covers all areas that a sea-run fish can access from natural barriers, such as cascades or falls, all the way downstream to the river mouth.

Scientists lavage the stomach of a bull trout to learn more about its diet, which can include juvenile salmon. Photo: Dave Shreffler, Shreffler Environmental

Sampling bull trout during netting and angling surveys involves collecting several types of information. A small part of a fin is clipped for genetic analysis. Most are tagged with FLOY tags—a small colorful tag with a numeric code that can be referenced later should the fish be caught again. Pectoral fin rays are sampled to learn age, home stream and whether the fish uses fresh or salt water. This data is similar to the information biologists learn from scale or otolith samples from salmon and steelhead. Bull trout stomachs also are pumped to study their diets, which can include juvenile salmon.

During the snorkel survey in the late summer, scientists and technicians snorkel the Dungeness and Gray Wolf rivers. The bull trout that were FLOY-tagged during the netting and angling efforts are observed and counted to calculate a population estimate in the Dungeness system, Sutton said.

“There has been quite a bit of interest lately in how salmon and bull trout interact with each other and that is one of the drivers for our work,” Burns said. “The better we understand bull trout, the better we understand the complexities of salmon recovery and river health.”

A bull trout underwater in the Dungeness River. Story: Tiffany Royal; Photo: Dave Shreffler, Shreffler Environmental