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Tori Dulemba's beach near Tahuya on Hood Canal was one place where many of the oysters died during the one-two punch of heat and low tides. // Photo: Tori Dulemba

Can biologists estimate the massive loss of shellfish caused by low tides, high temps?

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The putrid smell of rotting shellfish on some beaches in Puget Sound and elsewhere along the West Coast were a clear sign that large numbers of clams, mussels, oysters and other intertidal creatures were killed from exposure to extreme low tides, record-breaking temperatures and a blazing hot sun.

The total losses of shellfish that perished late last month may be difficult to estimate, but experts are beginning to piece together evidence from shoreline residents, state and tribal biologists, and commercial shellfish growers. Their goal is to describe what took place during the record-breaking temperatures of June 25-29 during some of the lowest tides of the past century.

The recent heatwave killed large numbers of shellfish throughout Puget Sound, including these butter clams in Quartermaster Harbor, Vashon Island. // Photo: Ron Carr

Understanding what happened during that June event might help avoid future shellfish disasters as the climate continues to change with no end in sight, officials say.

“We’ve been getting reports from Puget Sound to Canada, including the outer coast,” said Teri King, a shellfish biologist with Washington Sea Grant. “The effects of the heatwave were not uniform. Some areas got hammered and some seemed to escape (the problems).”

Tori Dulemba, who lives on the North Shore of Hood Canal near Tahuya, owns a south-facing beach with a gradual slope. Those conditions led to a long period of exposure to the hot sun when afternoon tides were the lowest since 2008 and when temperatures soared well above 100 degrees.

“You could easily smell the rotting shellfish,” Tori told me. “We knew immediately what it was. The oysters were cooked. The mussels were still attached, but the shells were empty. It was heart-breaking.”

The odor, she said, was much like the smell of dead salmon in areas where large numbers of fish still return to spawn and die in the streams. After a few days, the smell of dead shellfish dissipated, and it was gone after a week or so, but empty shells remained.

Teri King, who coordinates the Bivalves for Clean Water citizen education and monitoring program, said the first reports she received included descriptions of stressed clams digging themselves out of the ground and opening up on the surface of various beaches.

Based on reports, it seems that sand dollars were the first to succumb, followed by cockles, varnish clams, mussels, littleneck clams and butter clams, she said. There were also reports of dead Olympia oysters and Pacific oysters. Even barnacles turned up dead, while some sea stars and anemones also were killed.

A large number of the big moon snails common to Puget Sound got so hot that they literally uncurled themselves and came out of their shells, lying like balls on the beach, Teri said.

During the recent heatwave, tide levels were among the lowest in the past century. At Union on Hood Canal, shown here, the level was estimated to be at -4.37 feet at noon on June 25. Click to visit NOAA’s website for more specific data. // NOAA Tide Predictions

It seems that some areas were more sheltered from the sun or less affected by low tides because of the slopes of the beaches or the direction they faced. In general, problems were worse in South Puget Sound than in the north, Teri said, probably because the tides are more pronounced the farther south you go, leaving shellfish exposed for longer periods of time.

Teri and other officials are still taking observations and photographs from shoreline observers who were able to note the effects on shellfish caused by the extreme and extended heat. The Washington Department of Fish and Wildlife has provided an online form for observers to fill out, or they can send their information by Email.

Camille Speck, intertidal shellfish manager for WDFW, confirms the hit-and-miss nature of the massive shellfish die-off. While some public beaches were affected, others seem to have gotten by with minimal effects.

“What we saw at Dosewallips was very heartening,” Camille told me. “One-year-old or two-year-old oysters seemed to be doing just fine.”

She was speaking of Dosewallips State Park, a popular beach open to the public for shellfish harvesting. The beach lies on the western shoreline of Hood Canal, which may be better sheltered from the heatwave than the eastern shore or the northern shore around the “bend”.

Camille has yet to survey a number of public beaches, so she can’t say whether recreational shellfish seasons might need to be shortened to ensure future production. In some cases, quotas may be adjusted next year to compensate for losses, depending on the number of recreational harvesters and the amount of shellfish taken the rest of this year.

Photo: Ron Carr, Quartermaster Harbor

It was like a “perfect storm,” having such extreme low tides occurring coincidentally during the record-breaking heat, Camille said. Only two tidal periods in the last 100 years — one in 2008 and the other in 1916 — were lower, she said, and the temperatures climbed to levels never seen before in many places.

In Seattle, for example, the city had experienced 100-degree temperatures only three times in the past 126 years before they reached that level three days in a row, breaking the all-time record with 104 degrees on June 27 and again the next day with 108 degrees.

Meanwhile, some commercial shellfish growers have been gathering information to record their losses and possibly receive disaster relief from the federal government. Recent revisions to a federal program called Emergency Assistance for Livestock, Honey Bees and Farm-raised Fish (ELAP) may provide compensation for growers who can document their losses to the U.S. Department of Agriculture, officials say. For information, contact your county office of the Farm Service Agency.

A major hurdle in coming up with an estimate of actual losses — for commercial or noncommercial shellfish beds — is knowing what shellfish were present before the heatwave killed a portion of the shellfish.

Margaret Pilaro, executive director of Pacific Coast Shellfish Growers Association, said it is her understanding that growers must notify the USDA of potential losses within 30 days of the event. She has been trying to notify all of Washington’s certified shellfish growers of the possibility for financial aid to make sure that they don’t miss the deadline.

Tribal biologists also are out surveying the shellfish die-off, especially in areas where tribes have plans to harvest shellfish, as allowed by treaty. For state and private lands not cultivated for shellfish, the tribes are entitled to half the harvestable amount.

Biologists hope that a rough estimate of the total damage caused by the heat and low tides can be achievable, although such an estimate will be complicated by the patchy nature of the losses as well as the uncertainty about what was present in some areas before the event. For now, the main focus is to gather information from as many beaches as possible throughout Puget Sound.

In the topsy turvy world of climate change, Western Canada to the north experienced a similar but even more punishing heatwave, according to Tom Di Liberto, a meteorologist with CollabraLink Technologies. He says Lytton, British Columbia, reached 116 degrees on June 27, breaking the all-time record for all of Canada. But the oppressive weather was not over, as the temperature rose to 118 degrees the next day and then to 121 degrees on June 29. That is hotter than the desert town of Las Vegas, Nev., has experienced since records were first kept, according to Tom.

Likewise, the shellfish in British Columbia were reported to be cooking on the beach, perhaps even worse than in Puget Sound, as reported by Canadian news outlets.

Chris Harley, a marine biologist at the University of British Columbia, threw out an estimate of a billion shoreline creatures perishing in the Salish Sea as a result of the heat. That number, reported by Alex Migdal of CBC News, was crudely calculated by expanding the findings from a small area. The number subsequently raised a lot of eyebrows among experts on both sides of the border — but who could dispute it?

Commenting on the estimate, Chris Neufeld of Bamfield Marine Sciences Centre on Vancouver Island, said he was not surprised, adding, “It was very disheartening to realize we’re actually in this moment that we’ve been predicting for a long time.”

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