A Washington State diving team exploring the southern section of Hood Canal in Washington State has found virtually no fish in waters deeper than 20 feet, according to Washington Department of Fish and Wildlife head diver Wayne Palsson.
Overall, divers have counted 15 species of dead fish — including approximately 75 rockfish, which reside normally on the bottom.
Over the past several days, Thousands of dead fish have been reported from Annas Bay to Hoodsport, and experts state that the probable cause is suffocation from a lack of oxygen.
"There are still quite a few fish around," Palsson said, "but they’re crowded around in waters no deeper than 12 feet. From about 20 feet to 70 feet, there are virtually no fish down there."
The levels of dissolved oxygen in Southern Hood Canal have measured to be as low as 1.0 milligrams per liter. A measurement of 5 is considered stressful to marine life, and anything below 2 is considered lethal for some species.
Because of reduced populations of bottom fish, state officials do not intentionally kill fish to figure out their age or to take genetic samples.
Although the fish kill could have serious repercussions for the Hood Canal ecosystem, it does give biologists a chance to collect information that is usually unavailable.
"It appears that the dead fish show no signs of toxic contamination," he said. "What the marine creatures really need now is a lot of wind and rain to stir up the waters."
The low dissolved oxygen levels have been a problem in Hood Canal over the past several years. The problem is related to the increasing levels of plankton, triggered by excess nutrients that are present during sunny weather.