For two days last week, geologists, biologists, conservationists, professional fishing guides, political aides, journalists and at least one Alaska Board of Fisheries member gathered inside the Matanuska-Susitna Borough-owned fire hall in Wasilla for a salmon summit.

The hall is located on one end of a park strip where the city’s built a veterans memorial, a skateboard park, a playground, volleyball and basketball courts and a long series of ditches and swales designed, at least partly, to clean street runoff as it seeps into the groundwater.

Presentation at the summit, the second Mat-Su Salmon Science & Conservation Symposium, ran a gamut from descriptions of groundwater studies and habitat restoration to a “how-to” guide for replacing a salmon-impeding culvert with a new, salmon-friendly culvert that opened spawning areas previously blocked. (Tip: make sure the neighbors are involved before you start moving the road and the stream around—it’s called “buy-in.”) One presentation was about the pike invasion on the Alexander Creek, a 40-mile-long stream that runs roughly parallel to the Big Susitna River and enters the Susitna near it’s mouth. Alexander Creek is a short floatplane ride from Anchorage or Wasilla, (30 to 40 miles depending on where you leave from and where you land) and its headwaters are west of the Big Su and mostly untouched. It might as well be 1,000 miles from paved parking lots or aging gas stations or any of dozens of threats that come to mind when people worry about salmon habitat.

Northern pike were introduced to the Susitna drainage sometime in the 1950s and over the last five decades they’ve used the Susitna Valley’s network of rivers as highways, moving lake to lake and setting up in shallow coves and side-channel sloughs where they thrive. There’s no record of who introduced them, but biologist have long suspected sport fishermen because, well, because biologists tend to keep records when they start moving species around.

“They don’t like to hang out in the Big Su, it’s just not the right kind of water for them,” says Alaska State Department of Fish and Game biologist Samuel Ivey, who last spring tested netting for pike control on nine sloughs connected to Alexander Creek. Pike are “lie in wait predators”—they hide among water grasses and wait for their prey to swim by. “When you get into that real vegetated, slack water, that’s what [pike] like, and that’s what silver salmon smolt like,” Ivey says.

The Alexander Creek system once supported king salmon. One slide in Ivey’s presentations showed the king salmon escapement—fish that make it to spawning areas—counted from helicopter flights over the area every year since 1979. The chart shows some really good years, such as 1997, with the escapement peaking above 6,000 fish. It also shows a crash.

Fish and Game biologist have a minimum goal of 2,100 kings to survive and spawn in order to sustain the fishery. The goal hasn’t been met in five of the last seven years. In 2008, only 150 kings were counted.

“There used to be eight lodges (near Alexander Creek) in its heyday. I don’t think that any of them were open this year,” Ivey says. He said the drainage is a “gauntlet” young king salmon must run on their way to the ocean after spending a year in fresh water. The loss of the sport fishery has caused many people to ask Fish and Game managers what can be done.

The 2009 control netting was a feasibility study, set up only to learn what it would take to attack the pike with nets just after break-up when the shallow side-channel sloughs are at their deepest. “We covered about a third of the sloughs with two to three people and some outside support,” Ivey says. “It’s labor intensive, and it would be a full-scale project if it happened. If we incorporated [Alexander lake], it would be much bigger. The lake is completely infested with pike.”

The action took place along Sucker Creek, a tributary that supports most of the salmon-rearing left in the area. The biologist used some federal grant money aimed at eradicating or controlling invasive species for the project. They caught more than 1,100 pike with their nets.

Biologists sometimes use the poison rotenone to control pike, but Ivey says the Alexander drainage isn’t a good place for that. (In Alaska, rotenone is mostly used on landlocked lakes that don’t empty into streams, but there are chemicals designed to neutralize the poison at the downstream end of a treatment in flowing water—a technique sometimes used in the Lower 48.)

The sloughs’ up and down seasonal water level works against a poisoning strategy. Some water drops so much a slough disconnects entirely from Sucker Creek by the end of summer, Ivey says. “It’s a large and complex system—you’d knock them down (with rotenone) but they’d be back within ten years,” he says. And rotenone kills all the fish, not just pike.

Ivey’s study included mapping the sloughs to look for ideal net locations, and dissecting pike to look in their stomach. (The predators were eating salmon smolt, sticklebacks, leaches and frogs.) The study was preliminary work to design a pike-targeting project that might happen, or might not.

Throughout Ivey’s presentation he repeated the word: “feasibility”—biologists were at Alexander Creek this year to figure out how control netting might be applied, and not as the start of a new aggressive program.

In the fire hall meeting room a few hands shot up when Ivey finished his presentation.

Someone asked about funding. Ivey only said the Alexander Creek fishery was important to a lot of people and should have a lot of support. Another question spawned a brief side-discussion about stocking salmon in a pike-infested area (the short answer: it might help, if there’s other pike control methods in place too). Someone else wanted to know if control netting needed to be an annual affair in order to work. Ivey thinks a netting program would need to be perpetual.

“It would be like a band-aid you would never take off,” he said.

scott@anchoragepress.com