Survey says: Healthy watershed
It's a cold and windy morning near the mouth of Tryon Creek. A few hundred yards upstream, above the culvert running below Highway 43 at the dividing line between Portland and Lake Oswego, thousands of cars and trucks speed past the tiny creek without much thought of what's going on down below.
That's typical for small, urban streams like Tryon Creek. As metropolitans, it's easy for us to overlook these miniscule trickles of water that contribute to the larger, more prominent waterways that define the landscape of our cities and state.
But down here at the mouth of Tryon Creek, the U.S. Fish and Wildlife Service is collecting important data that has wide implications on both the wild habitat of these streams and the urban infrastructure surrounding them.
Today, Brook Silver and Brian Davis of the Columbia River Fish and Wildlife Conservation Office are electrofishing in Tryon Creek. It's a process that allows these fish biologists to stun juvenile fish hiding in the creek so they can easily capture, identify, measure and release the fish without causing them harm.
Silver makes her way up the stream toward the culvert using a large wand-like rod with a sort of lasso attached to it that emits an electric shock. On her back connected to the rod is a pack that carries an electric charge. The pack is a bit clunky and looks like something out of a "Ghostbusters" film.
Directly behind her, Davis holds a net, ready to catch any fish stunned by Silver's shock so it can be placed in a bucket full of river water where they can recover.
It's a slow process, but after about 30 minutes of electrofishing the pair of biologists have caught four fish, three salmonids and one tiny reticulate sculpin.
The mission is to find coastal cutthroat trout, a specific species of trout which they found in upper sections of Tryon Creek earlier in 2017.
Silver, along with a team of colleagues from USFWS, released a study explaining the findings regarding the status, abundance, distribution and habitat preferences of coastal cutthroat trout in Tryon Creek.
The population of coastal cutthroat trout in Tryon Creek exhibits characteristics of an established, viable and sustainable population, according to the report. These characteristics are similar to those found in populations not influenced by urbanization in forested areas. The Tryon Creek population displays multiple size classes, exhibits migratory behavior, is genetically diverse, and free of pathogens. This comparison of parameters to a non-urbanized population suggests an urban stream can support a healthy fish population.
Silver and Davis are able to observe the migratory behavior of cutthroat trout by tagging juvenile fish with passive integrated responders or "PIT tags," an electronic tag measuring 12 millimeters long by 2.1 millimeters in diameter. Pit tags can be coded with one of 35 billion unique codes, so each fish they tag has a unique code attached to it.
A series of gates with electronic signals that read when a tagged fish passes through have been set up at the mouth of Tryon Creek where it meets the Willamette River, and multiple gates means that rather than getting a "yes" or "no" on whether a fish passes through the gate, USFWS can actually identify which direction the tagged fish are heading, whether that's upstream or toward the Willamette.
"I think the detection of fish coming and going from Tryon Creek shows this habitat is connected, and that these fish do have the ability to exit and return," Silver said. "These off-channel habitats are used as refuge for juvenile fish heading to the ocean."
While they didn't find any coastal cutthroat trout on this outing, Silver and Davis were able to catch three salmonids, including two chinook salmon and one coho.
It's a great consolation, considering the coho salmon is listed as "threatened" federally and "endangered" in the state of Oregon. Its presence in Tryon Creek is a good indicator that improvements made to this particular stretch of Tryon Creek by the City of Portland have positively impacted the habitat, and Silver believes the fact these fish are present shows the City that the culvert is in fact used by fish to gain access to other parts of Tryon Creek upstream.
Kaitlin Lovell is manager of the Science Integration Division in the City of Portland's Bureau of Environmental Services. She works with USFWS to gain information about watershed health and fish populations in areas like Tryon Creek, especially as how it pertains to plans to rebuild the culvert below Highway 43.
Pending congressional approval for funding to allow the U.S. Army Corps of Engineers to begin design work, Lovell says the City will use Silver's report and data collected by the PIT tags to guide the project to better allow the free passage of coastal cutthroat trout and other fish through the culvert by making sure these juveniles have slow moving pockets and rest spots to ensure safe passage.
"Fish are knocking at the door of that culvert," Lovell said. "As soon as we open it they will be making their way up the culvert, and this data tells us which species and where in their life stage these fish are that are using this habitat."
The Tryon Creek Watershed Council, along with City of Portland, City of Lake Oswego and Oregon Department of Transportation have put together a thick stack of letters urging Oregon Senators Ron Wyden and Jeff Merkley to push for the funding to be included in Congress's omnibus budget bill later this year, but Lovell believes any extra support from individual citizens would be a huge benefit for the project's future.
For Silver, tromping around Tryon Creek, tagging fish and taking other measurements of the habitat is all in a day's work, but the real task is using that information to improve the Columbia River's watershed as a whole for the continued preservation of all the fish that it is home to.
"It takes work to preserve and maintain large connected spaces like Tryon Creek," Silver said. "If we want to protect sensitive species in urban habitats, it is essential that we promote these urban spaces and engage the community. By increasing preservation and promoting stewardship, we can positively affect not just the cutthroat trout in Tryon Creek, but everything else that lives downstream."