Hood Canal fish suffocate

Scientists are scrambling to document what appears to be the most widespread fish kill to date in Hood Canal, the deep and poorly flushed waterway that researchers say suffers from oxygen levels at their lowest ebb in at least five decades.

Pollution from septic tanks and possibly other sources is strongly suspected of aggravating the problem.

Reports from area residents started early Tuesday of dead shrimp, Dungeness crab, lingcod, flounder, sand lance and other fish. The kill stretches about six miles along the "Great Bend" of the 60-mile-long, glacier-carved fjord.

Low-oxygen water in the bottom of the canal quickly surged up to overtake fish between midnight and 6 a.m. Tuesday. Scientists were able to measure it because of a major new scientific investigation started after fish kills in 2002, 2003 and 2004.

"What we don't know is why it happened so quickly," said Brad Ack, director of the Puget Sound Action Team, the state agency coordinating the recovery of Puget Sound and Hood Canal. "It focuses our attention again that we have a serious problem in Hood Canal, and just because the last couple of years haven't seen these kinds of fish kills doesn't mean that the problems have gone away."

Greg Bargmann of the state Fish and Wildlife Department said officials had made no estimate of the number of dead fish and may not try to because so many are thought to have died and sunk to the bottom.

But the magnitude of this kill appears similar to that of the 2003 event -- the largest known to date -- and this one covers more of the waterway.

"It appears the (oxygen) levels are getting worse in the sense that they're covering a larger area of the canal and the oxygen levels are getting lower," Bargmann said.

The waterway has been closed to fishing for bottomfish, squid, herring and other fish because of the stress low oxygen levels cause, he said. The only fishing allowed in the canal now is for coho salmon, which are sure to move away from areas where oxygen levels drop, he said.

No firm cause for the fish kill has been established, said Jan Newton, a University of Washington oceanographer heading up a study of the waterway. But it appears two factors could be at work, she said.

First, winds that had come from the north for many weeks shifted in recent days to come from the south -- including the big storm that drenched Seattleites early Tuesday -- just as Hood Canal's oxygen levels were dropping.

The southerly winds are thought to have pushed the water in the upper levels of the canal, which has the most oxygen, to the north. Then, low-oxygen water from the bottom of the canal surged up, catching some slow-moving fish off guard.

The second factor thought to be at work is the natural infiltration of low-oxygen seawater at this time of year, which is related to larger-scale oceanographic events tied to the Pacific Ocean and the Strait of Juan de Fuca, Newton said.

The long stretch of sunny days Western Washington saw in recent months also is at work, Newton said, because that fueled the growth of single-celled plant plankton, which are microscopic algae. Those were subsequently gobbled up by animal plankton and ended up in their waste.

That waste sank to the bottom, where bacteria munched on it. The more waste, the more bacteria -- just like your compost pile. And bacteria, just like humans, consume oxygen.

Scientists are still trying to figure out how much septic tanks and other human-caused pollution feeds that process. But they do know that nutrients in sewage and in the incoming ocean water fuel explosions of the one-celled microscopic algae that drive the whole process.

"I have a strong feeling that it will (turn out to be) a combination of natural and human-caused factors, but what we want to understand is which of the human-caused factors are worse so that we're tipping the balance," Newton said.

Linda Farmer, a spokeswoman for the Puget Sound Action Team, said it's impossible to extrapolate what's happening in Hood Canal to future problems elsewhere, but, "We have been warned that if things continue going in the direction they're going without anybody stepping in, the rest of Puget Sound could start looking like Hood Canal."

P-I reporter Robert McClure can be reached at 206-448-8092 or robertmcclure@seattlepi.com.

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