While securely nestled within gravel beds, salmon eggs need proper levels of dissolved oxygen (DO) to survive.
As part of monitoring the restored Jimmycomelately Creek, the Jamestown S’Klallam Tribe is testing the DO levels within the streambed’s gravel, where salmon make their egg nests, also called redds.
The tribe is taking water samples from 21 locations within the creek. To get a sample, the tribe engineered a special tube and pump system. A small aquarium air stone is attached to one end of a 68-inch long plastic tube. The stone is buried 7 inches below the streambed surface, mimicking the typical depth of a salmon redd. The remaining 59 inches of tubing floats in the water. When gathering a sample, a special pump is attached to the exposed end, drawing the water up from within the gravel.
Preliminary results show that DO levels are acceptable in the upper stream where the streambed has not been altered. In the lower reach, near where the creek empties into Sequim Bay, results are mixed. Some areas are show sufficient DO levels while others are less than what is needed for egg incubation.
Dissolved oxygen measuring at 8 milligrams per liter or more is considered satisfactory; Samples measuring 3 milligrams per liter or less are considered lethal.
“It’s too early to tell if the inconsistent levels in the lower creek are because the creek is still recovering from past farm practices, restoration efforts or other factors,” said Lori DeLorm, a Jamestown S’Klallam natural resources technician. “With a few more years of data collection, we will get an idea of which sites are meeting the oxygen demands for incubating eggs and emerging fry.”
About 25 acres at the mouth of the creek were restored in 2005 after a century of development altered the habitat. Salmon prefer to lay their eggs in clean, sediment-free gravel, where water is cool and the creek velocity is slow. Hood Canal summer chum salmon, listed as “threatened” under the federal Endangered Species Act, as well as coho and steelhead are among salmon species found in the creek.
The work, which began in August 2010, is funded by a grant from the Environmental Protection Agency.