Adventures in Coho Stream Surveying


Jon Oleyar likens his stream surveying to the television show “CSI: Crime Scene Investigation.” But rather than seeking evidence to solve a crime, the Suquamish Tribe fisheries biologist hikes Kitsap County’s streams for evidence of spawned-out salmon carcasses – particularly for coho.

“I feel like I’m part of a CSI team – Coho Stream Investigator,” he said. “Just finding them is the hard part. You have to think like a fish or a predator – ‘Where would I go to spawn?’ or ‘Where would I go to eat this fish?'”

He finds carcasses in various states, from fully intact to partially eaten. Based on his observations, he can figure out what happened to the latter, as he did on a recent survey.

“This is a perfect specimen,” he said of a discovered intact fish. “It’s still relatively fresh and a critter – probably a river otter – recently attacked and killed this female. By noting the absence of eggs and a worn tail fin, from digging a salmon egg nest in the gravel, I would say she most likely spawned prior to being killed.”

It’s the ideal scenario – the fish gets to spawn, the predator gets what it needs and Oleyar is still able to collect his sample. He measures its length, makes note of the gender and checks the snout for a coded-wire tag. The millimeter-long tag contains information about which hatchery it came from and when it was released. He also notes if the fish’s adipose fin is missing or intact. If it’s missing, it’s a hatchery fish; if it’s intact, it’s most likely a wild fish.

Carcasses play an important role in the wild and in science. The decaying fish are a source of food for animals and provide nutrients for important streamside vegetation that help improve water quality. For biologists, counting dead fish gives them a good idea of how many are coming back to their natal streams. It also helps determine species and stock compositions, habitat changes due to human or natural influence and geographic distributions of the fish from year to year. Oleyar has been conducting spawning surveys for tribe for more than 10 years.

“The intense work the tribe has done to find and count carcasses throughout the Chico watershed has paid off,” Oleyar said. “All this information has been very powerful in helping the tribe monitor the various salmon population trends over the last decade, understand their needs and observe how they react to changes to their environment.”

Since 1998, between the months of October and December, Oleyar has made weekly hikes up and down Kitsap’s numerous salmon-producing creeks, including Dickerson Creek. The stream is a tributary to Chico Creek, one of the most productive salmon streams in Kitsap County, with an average of 30,000 chum returning every fall to spawn.

Coho stock information is highly important to the tribe. Its extensive coho database is one of the strongest in the state and is often consulted by local and state agencies for management and other informational needs.

“In the 10 years we’ve been doing this, we sampled well over 10,000 coho alone,” he said. “Some hatcheries haven’t seen that many come back since they opened their facility.”

Oleyar was surprised when he found more than 100 coho coming back to Dickerson Creek in the 2008 fall season; normally only a handful return. At the same time, heavier-than-usual rain in late November and early December made it difficult for fish to get upstream. It also potentially wiped out salmon egg nests that had been dug by earlier returning salmon.

Still, the tribe’s intense dedication to monitoring these streams is paying off.

“Pacific Salmon Treaty Research Funding is instrumental to supporting this program,” Oleyar said “It’s the only way we can keep a good eye on what’s coming back to our area streams and continue to build on our knowledge of those salmonid populations by collecting key fish and habitat data.”


For more information, contact Jon Oleyar, Suquamish Tribe fishery biologist, at (360) 394-8445 or [email protected]; or Jay Zischke, Suquamish Tribe marine fish program manager, at (360) 394-8444 or [email protected]; or Tiffany Royal, Northwest Indian Fisheries Commission, information officer, at (360) 297-6546 or [email protected].