More insects mean healthier streams and fish

Hard, lean and strong, an inch-long stone fly lurks in the depths of Woods Creek north of Monroe.

Nearby an unaware mayfly scrapes a meal of algae off a rock.

Suddenly the stone fly scurries across the creek bottom, lunging at its smaller prey, impaling it with long, sharp mandibles.

Tearing into its meal, the stone fly scans the surrounding water. It needs to keep watch for hungry fish looking to make it a snack.

The rivers and streams of Snohomish County are an underwater bug battlefield. Every day is a life-or-death struggle. Oddly, experts say, the more violence among insects, the healthier the stream.

The more stone flies, mayflies and caddis flies there are in streams, the more able they are to support viable fish runs, scientists say.

Because aquatic insects need the same cool, clean and oxygen-rich stream conditions desired by salmon, trout and steelhead, and because the bugs stay put while fish are on the move, insects have emerged as the best way to measure a stream’s health, said Tom Murdoch, executive director of the Everett-based Adopt-A-Stream Foundation.

Snohomish County collects and counts insects from a random selection of the more than 3,000 miles of streams and rivers. Over time, the information will be used to identify which waterways are becoming sterilized by sediment that chokes growing fish eggs, warm temperatures that make it tough for fish to breathe, and pollution that weakens fish.

Already, many urban Snohomish County streams are getting failing grades. That could spell disaster for salmon, steelhead and trout, experts say. For many people, living near streams alive with fish helps define what it means to live in the Northwest.

According to state stream surveys, fish populations in tiny urban streams that drain directly into Puget Sound are the county’s worst off. But all the streams that eventually flow into Lake Washington – such as North and Swamp creeks – aren’t far behind.

And fast-paced growth in north and west Snohomish County is putting pressure on streams from Stanwood to Lake Stevens to Sultan.

Once-abundant populations of stone, caddis and mayflies have all declined just as dramatically in those same streams, Murdoch said.

“These aquatic insects are like canaries in a mineshaft,” he said. “When the canaries croak” the miners aren’t far behind.

Insect lives tell a tale

Cami Apfelbeck sits in the middle of Woods Creek on a warm September afternoon. Her back is to the current, the water parting around her at waist level. She sifts through gravel on the stream bottom, looking for insects one rock at a time. Chest waders and rubber gloves keep her dry.

“Ah, found one,” she says, holding up a tiny rock with an even tinier blue creature clinging to it.

It’s a worm-like caseless caddis fly, about the length of a pencil eraser, but much thinner.

A few inches away Valerie Streeter holds up a small rock.

Come closer, she gestures.

What looks like a bunch of black bumps is really a dozen or so tiny houses built up all over the rock, crafted by a species of caddis fly that glues together tiny gravel shelters.

The head of one caddis fly can be seen peeking out of its front door.

“Sometimes it’s hard to tell the bugs from the crud,” Streeter says.

Insect samples have been taken at a few select streams since 1997, but recently the county decided it needed something more comprehensive, said Kathy Thornburgh, leader of the county’s water quality team.

So, beginning in 2005, her office started randomly sampling streams from across the entire county. The work is done in August and September.

The intent is to use the presence of insect populations surveyed in each stream to gauge how healthy it is for fish, Thornburgh said.

South county was randomly sampled last year. The Snohomish River basin is being sampled this year. It’s the Stillaguamish River basin’s turn next year. Thornburgh said the goal is to sample 30 streams from each basin each fall.

The county will return to the same sites every three years, creating a database that will show which streams are getting worse over time. The program is patterned after the technique King County started using in 2002.

Random samples are needed because there is no way to sample all local streams, which together cover about 3,000 miles.

The research will help fish biologists and decision-makers find better targets for fish recovery efforts, Thornburgh said.

Chinook salmon and bull trout (the sea-going version often known locally as Dolly Varden) are listed as threatened on the federal endangered species list, and steelhead may soon join them there. Biologists believe populations of other salmon species are also shrinking in many Snohomish County rivers and streams.

Restoration can come in many forms, including planting native vegetation along stream banks; tearing out pavement so rain can percolate into aquifers that keep stream flows up; and building storm water retention ponds to keep waves of rainwater from washing into streams and gouging out fish spawning nests.

Back in the field, taking good aquatic insect samples start with finding a nice riffle, where the creek is moving fast over a rocky bottom, Apfelbeck said.

A device called a Surber Sampler – it looks like a large-format camera laid on its side – is placed on the creek bottom, the opening covering exactly one square foot.

Apfelbeck and Streeter sift through all the rocks and gravel covered by the Surber opening, carefully trying to shake loose any hiding insects. A long net trailing behind catches everything that breaks loose.

“We gently encourage them to give up their lives for science,” Apfelbeck said.

Everything caught in the fancy net is packed into a container that sits at the bottom of the net. Just before the container is sealed, alcohol is poured in, preserving (and killing) all the insects so they can be sent to a lab to be identified and counted.

Index at work

Fish move. Whether they swim 50 feet downstream or all the way to the Pacific Ocean, fish never stay still, making it a challenge to measure why salmon and steelhead are struggling in Snohomish County streams and rivers.

Perhaps ocean conditions were bad, or there could have been too much fishing. A plugged culvert could be keeping adults away from a particular stream.

Aquatic insects, though, stay put.

“The bugs live in and around the stream (all) year,” said Jim Karr, a retired University of Washington ecology professor. “So if the invertebrate community is healthy, then the stream is healthy.”

Karr developed the Benthic Index of Biological Integrity, a complicated matrix that uses the trio of insects (and a few others) to measure stream health in the Puget Sound region.

It’s his index that will be used to give Woods Creek a grade once the insects Apfelbeck and Streeter collected are identified and counted.

The presence or lack of certain aquatic insects gives clues about what’s wrong with a stream, Karr said.

Just as wolves and grizzly bears are in mountains, stone flies are the top insect predators in streams.

They are generally bigger and live longer than the insects that make up their diet. They also are more vulnerable to changes that limit their health and food supply, such as drops in oxygen levels, temperature swings and pollution.

By contrast, some mayfly species like it when such nutrients find their way into streams because it means there will be more algae to eat.

If there are no stone, caddis or mayflies hiding in the crevices between rocks, that means the creek has too much sediment, Karr added. That’s another bad omen for salmon, because sediment smothers eggs.

Attributes of each insect species found in area streams are factored into the index, Karr said. The result gives clues about why fish struggle in that section of stream.

“If you were to bring Jim Karr a tray of insects that you gathered from a stream, he could, without going to the site, generally tell you what the health of that stream is,” said Murdoch of the Adopt-a-Stream Foundation.

The foundation uses Karr’s index to teach people how to make streams in urban Snohomish County neighborhoods more friendly to insects, and therefore, better for fish.

Over time, the foundation has found there are fewer insects and less diversity among insect species in most of the streams being monitored, Murdoch said.

“Things aren’t looking too good from a salmon’s perspective in the urbanized parts of Snohomish County,” he said.

There’s hope if people will make their homes and businesses more stream friendly, he said.

“If we can get the community to do its part, we can certainly slow down the decline of the fish runs and in many cases start bringing them back,” he said.

Smaller building sizes are key, as is less pavement, Murdoch said. That will reduce bursts of runoff after storms.

Another key is to keep vegetation growing along the banks of streams, where it can provide protective cover and shade for bugs and fish.

Take care of those problems, and the fish food will rebound. Then the fish will return.

Just look at Pigeon Creek No. 1 in Everett’s Forest Park, he said.

No salmon had been spotted in the creek for more than 30 years when students at Jackson Elementary School decided to adopt the stream in the early 1980s.

Storm water runoff was curtailed, nonnative vegetation was removed and woody debris for young salmon to hide under was dropped into the stream.

A small population of coho salmon has been reestablished in the stream, with a few adults returning every year to spawn a new generation.

“In 1987 the first salmon in over 30 years came back to that creek,” Murdoch said. “Those fish were introduced by the kids at Jackson Elementary School. What would have once been considered a lifeless stream has life again.”

Reporter Lukas Velush: 425-339-3449 or

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