Juvenile salmon are using the new habitat at zis a ba in the Stillaguamish estuary, where the Stillaguamish Tribe restored tidal flow in October 2017.
Formerly part of the tidal marshes connected to Port Susan and south Skagit Bay, zis a ba had been isolated from the river and tides by a dike built more than 100 years ago to protect a homestead from flooding. The tribe purchased the property in 2012 with the intention of setting back the dikes to create more rearing habitat for juvenile salmon, especially chinook. It was named zis a ba for a former tribal chief.
“When the fish come out from their spawning areas in North and South Fork Stillaguamish in the spring, they need places to grow larger before they head offshore, and these tidal wetlands are an important stop on that journey to the ocean,” said Jason Griffith, Stillaguamish fisheries biologist. “This is an area that fish historically used to use, but they have been cut off from it for a very long time.”
Tribal natural resources staff along with staff from the Skagit River System Cooperative (SRSC) are monitoring the area to see if the restoration project is working as designed. This work includes collecting genetic information from juvenile salmon to measure the benefit of the project beyond the Stillaguamish River.
Biologists use seines to collect fish in several sites on a biweekly basis. When they find juvenile chinook, they take a small fin clip for DNA testing before returning them to the estuary.
“The DNA will tell us what river system they came from,” Griffith said. “This area is kind of a mixing ground for the Whidbey basin.”
“Even though the project is intended to improve Stillaguamish River stocks, Skagit River chinook have access and use this estuary as well,” said Mike LeMoine, a biologist with SRSC, which is the natural resources extension of the Swinomish and Sauk-Suiattle tribes.
Research in other river systems, including the Skagit and Snohomish, has shown that increasing tidal wetlands leads to fewer fish dying before they reach adulthood, and therefore larger numbers of chinook returning to spawn, Griffith said.
“These projects are pretty important for chinook recovery, for orca recovery, and for ensuring that the tribes and non-treaty fishers have lots of opportunities,” he said.