The portable dam, which includes traps and augers to lift the fish into holding tanks, is designed to capture every fall chinook salmon that has made it through a gauntlet of fisheries that stretches from Alaska to the river.
Once their migratory journey is halted, tribal crews sort the fish into two distinct groups: fish that were reared in one of the tribe’s two downstream hatcheries and fish that were born to naturally spawning parents upstream.
Life’s journey for the hatchery fish, which are distinguished by their clipped adipose fins, ends at the fish weir. They become food for tribal elders and area food banks.
The goal is to send the naturally spawned fish upstream to spawn, free of interference from hatchery fish, which are considered less productive than their wild counterparts and less capable of warding off predators and disease.
“There’s nothing else like this on a Puget Sound river,” noted David Troutt, natural resources director for the tribe. “It’s a pretty big tool to help us meet harvest goals and recovery goals for Puget Sound fall chinook.”
The weir, a small dam, has the support of the state Department of Fish and Wildlife, which co-manages Puget Sound salmon stocks with the treaty tribes.
“We applaud the tribe for their progressive view of salmon management,” noted Pat Pattillo, policy coordinator for the state Department of Fish and Wildlife. “We’re excited about the weir and want to see it be successful.”
When Puget Sound chinook were listed as threatened under the federal Endangered Species Act in 1999, the state Department of Fish and Wildlife, Puget Sound tribes, conservation groups, anglers and others faced the daunting task of bringing the iconic species back from the brink.
In the Nisqually watershed, the tribe took the lead and essentially had to start from scratch. That’s because native Nisqually River chinook were wiped out in the 1960s by indiscriminate mingling with hatchery fish, hydroelectric dam operations upriver and over-harvest in marine waters and the river.
The weir is part of an updated Nisqually chinook recovery plan that includes a healthy dose of habitat improvements in the watershed.
Since 2000, the tribe and its many watershed partners have protected 74 percent of the river shoreline from development, created more than 900 acres of estuary near the mouth of the river, and restored nearly 7 miles of shoreline along two of the river’s main tributaries – Ohop Creek and the Mashel River.
“Given the history of chinook salmon in the Nisqually, restoring habitat is absolutely necessary before you start worrying about the mix of hatchery and natural origin fish on the spawning grounds,” Troutt said. “To develop a local stock, we need to be sure that only natural origin fish are spawning in the river. That is where the weir comes in.”
The tribe also is experimenting with new ways to harvest chinook salmon in the river, including tangle nets and beach seining nets that allow tribal fishers to pass upstream the naturally spawning fish and keep just the hatchery fish.
More than half of the naturally spawning Nisqually chinook are captured in fisheries all along the West Coast. The goal is to keep reducing that number over time so some 2,000 naturally spawning fish can be passed upstream to spawn while still sustaining a annual harvest in the river of 10,000 to 15,000 chinook, according to the chinook-recovery plan.
The tribe purchased the weir with a $1.6 million grant from a federal hatchery-reform program. It was tested in the river late last summer, but crews had trouble keeping it stationary in the fast-flowing river.
When it was reassembled this year, it was secured by five cement anchors stationed in the woods and a heavy-duty cargo ship chain. A gate at one end of the fence can be lowered to allow boats to pass, and fish can be corralled and sorted on either side of the weir.
The fish are mechanically hoisted into a holding tank on the riverbank, where they are measured and checked for origin and sex. The natural spawners are equipped with a numbered jaw tag for use in spawning ground surveys and a DNA sample is taken for long-term monitoring of fish productivity.
“I think the weir is a good idea,” said Robert Wells, a tribal member and one of six employees who operate the weir.
“It’s going to answer a lot of questions about the fall chinook.”
This year’s weir operation has been complicated by the numbers of returning fish, which appear to be much lower than the 26,000 that were forecast. As of Thursday morning, only nine naturally spawning chinook had been passed upstream and 28 hatchery fish had been intercepted. Typically, this would be the midpoint for the chinook run in the river.
“Everybody’s a little bit on edge,” Pattillo said.
The federal permit for operation of the weir calls for at least 870 fish, regardless of origin, to spawn upstream this year, said Bob Turner, regional administrator of NOAA Fisheries’ salmon-management division.
“I think most of us expect some hatchery fish will be passed upstream this year,” Turner said, adding that the long dry-weather spell could be delaying the salmon run. “The question is, how many?”
Regardless, the weir will be a valuable tool over time, Turner said.
Sometime in October, the tribe’s crew will pull the fence out of the water in 5-foot sections and haul all the equipment away for safekeeping.
“It’s kind of like a huge carnival ride,” said tribal salmon-enhancement manager Bill St. Jean. “We truck it in and assemble it, then tear it down and truck it out.”