Juvenile salmon in Grasser’s Lagoon got a check-up, of sorts, early Wednesday morning.

Researchers from the Skagit River System Cooperative spent several hours catching and releasing salmon and running tests on the water quality of the pocket estuary.

It is the second year researchers have monitored Grasser’s Lagoon, which the cooperative classifies as a pocket estuary.

Rich Henderson, a fisheries biologist with the cooperative, said research on Whidbey Island and in Skagit Bay generally begins in February and runs through October.

Eric Beamer, research director for the Skagit River System Cooperative, said the standard research period of February to October covers the period when juvenile chinook salmon will be in costal waters.

“We’re mainly trying to establish when are juvenile salmon in that lagoon habitat and when are they not in that lagoon habitat,” Beamer said.

In Grasser’s Lagoon, he said, most of the juvenile chinook have left by the end of June and there are virtually none present by October. That absence of fish also correlates to the time of the year when water temperatures rise near shore.

“It varies a lot,” Beamer said of the number of salmon researchers find. “The 2004 data for chinook were really poor.”

Those poor numbers were due in part to flooding which washed many of the salmon eggs out of the gravel beds before they could hatch.

During peak catches of other salmon, like chum, Beamer said up to 200 juveniles could be caught and released.

While they aren’t testing for diseases among the fish, researchers are looking at the size and weight of the juveniles to determine their health.

The data researchers gather over the years allows them to create a life history model of the salmon that could be used in the future for habitat preservation or restoration. Costal lagoons have been among the hardest-hit in recent years, Beamer added.

The Skagit River System Cooperative, based in La Conner, conducts fisheries and environmental services for the Swinomish and Sauk-Suiattle Indian tribes. The cooperative monitors 14 sites throughout the Skagit Bay area, including 10 beaches and four pocket estuaries.

It began researching Chinook salmon in 1995, and an expanded program was started at Grasser’s Lagoon in 2004.

On Feb. 4, the Island County Beachwatchers will host a class on the importance of pocket estuaries to juvenile fish, and explain some of the research the cooperative has been conducting.