This is one in an ongoing series of posts by artist Elizabeth Conner, artist in residence on the Tolt River. Elizabeth is working with scientists who are monitoring the river in the aftermath of a recent restoration project near Carnation. She will be formulating ways to share that information with the public.
April 25, 2011, 8:15 p.m.
I meet Hans Berge, and fellow King County ecologists Dan Lantz and Laura Hartema, on the north bank of the Tolt River. Hans and his colleagues will sample fish and their habitats at flow levels comparable to those existing when they did similar work two years ago, prior to completion of the floodplain restoration project. Project designers begin with certain assumptions. In this case, according to Josh Latterell, “We think the fish prefer certain slow-water habitats, but we need to find out if they actually tend to select one type of habitat over another.”
Hans has tracked the flow gage on the Tolt, in order to schedule this evening’s activity. One of the three previous “fish counts” was conducted at 760 cubic feet per second (cfs), a measure of the volume of water passing by a point on the river. When we arrive at the site, the rate of flow is 756 and rising, which is “close to perfect,” according to Hans.
As we wait for 9 p.m. and darkness, Hans explains: “We will seine bank, bar, backwater, and side channel habitats, to measure density of juvenile salmon and steelhead.” These relatively shallow areas, with low-velocity flows, are good for juvenile salmon, especially Chinook. Fish counts take place at night, when salmon do not need to hide from predacious birds or other fishes, but are actively feeding and therefore susceptible to being caught, temporarily, by the monitoring team.
Hans outlines some of the newly-visible benefits of the restoration project. During the day, smaller fish can hide in the woody debris accumulating in the floodplain. At night, they seek habitats “in the lee of the wood,” low-velocity, shallow water, sheltered areas formed behind wood that obstructs flow. As the fish mature, increase in size, and gain swimming ability, they are less vulnerable to predators, and move further into deeper, swifter waters for feeding.
Laura, Dan and Hans call out directions, ask questions, argue, banter, and share surprises while setting and pulling nets, or “seines.” I appreciate the flow of their conversation, as I attempt to take notes on the fly. At one point, I hear “Do it on the down,” which sounds intriguing. This means setting the net heading downstream and then hauling it upstream to close it around the catch. My job is to time each haul, from the moment the team begins to move the net in a wide circle in the water, to the time they pull the haul onto the shore.
It is a beautiful night: warm and not raining, a sweet and rare interlude in one of the coldest and wettest recorded winter and spring seasons in the Pacific Northwest. Once I figure out how to juggle camera, flashlight, stopwatch, pencil, paper, and my inevitable clumsiness in chest waders, I watch three people engage in a slow specific dance, deploying a large net across flowing water. Their actions, the net and the water are illuminated, intermittently and rhythmically, by the miner’s lamps on their heads. Each haul takes about a minute, but the experience of watching this mesmerizing, illuminated watery dance in the dark was, and remains, mysteriously “outside of time.”
The fish caught in each haul are carefully transferred from the net into large plastic buckets. I record the Haul # and elapsed time on a slip of waterproof “Rite in the Rain” paper, and drop it into a designated bucket. It floats among the fish and some “bycatch,” mostly cottonwood seeds, which I initially confuse with the tiny juveniles.
The team gathers on a gravel bar, at a folding camp table illuminated by a battery-operated lamp. Laura removes each fish from the bucket with a small net, placing it in a plastic container of water dosed with a sedative, to make the fish easier to handle and prevent injury. Hans says, “I prefer to dose them really light – it’s easier for them to recover.”
Hans measures each fish, from its nose to the fork in its tail. “To measure them, you have to head them upstream,” he says, referring to the device he created: a very effective assemblage of a transparent ruler and a length of PVC pipe, capped at one end to hold water. The species of fish, its weight, and the “nose to fork” measurement, are recorded on the data sheet for each haul. The length of the fish provides information about how long it has been out of the gravel and at what rate it is growing. Weight is also important, as the biomass of fish per unit stream area is another measure of habitat productivity. Once data is recorded, each fish is transferred back to the bucket, and then returned to the river.
Fish from hauls 1, 2 and 3, in side channel habitat, include some of the following, with measurements in millimeters, called out by Hans, and recorded by Dan:
Shorthead Sculpin – 64; Chinook – 39; Chinook – 53; Torrent Sculpin – 48; Riffle Sculpin– 45; LND (Long-Nosed Dace) – 56; “Little” Coho – 36; Riffle Sculpin – 63; Chinook – 48 mm, a “fry.”
The term “fry” refers to a life stage that begins after fish emerge from the gravel, and prior to their migration to salt water. As they get closer to making the journey to salt water, they go through a transformation to become smolts. At some point during Haul #2, excitement erupts: A river lamprey – 113 mm. The team tells me this is a very ancient creature. It looks like a very large worm.
Work continues for several hours: a total of five hauls. I appreciate the simple question driving fish counts: “What do the fish want?” Interconnected and nuanced answers will help ecologists prioritize and balance habitat-related changes to be set in motion through the design of future projects. I wonder if urban planners engage in similarly sensitive monitoring of new projects, to explore “What do the people want?”
Vegetation, gravel and wood surveys are scheduled for July.
Photos by Elizabeth Conner
