Why dead fish are washing up on the Sandy River's banks

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TROUTDALE, Ore. —

Thousand Acres Park just outside of Troutdale is a popular destination for dog walkers. Bordered by the Sandy and Columbia rivers, the park offers wide open spaces, forested paths and access to both rivers.

But the riverbanks in the park have a somewhat grisly new inhabitant: hundreds, possibly thousands, of dead smelt.

Sierra Schertz comes to the park once a week, and her first concern after seeing the fish was for her dog.

"We didn't really know why they were here," Schertz said. "We didn't know if there was something wrong with the fish so we’re just keeping (the dog) away from the fish."

But wildlife officials said there is no reason to worry. Smelt are anadromous, meaning they hatch in freshwater rivers, spend much of their adult life in the ocean, then return to the same rivers to spawn before they die.

What's showing up on the riverbanks outside of Portland is the natural end to the species’ life cycle.

"They spawn in the water, but then after that they start to die and then they don't last very long," said Tucker Jones with the Oregon Department of Fish and Wildlife

Jones noted that smelt typically only live for two or three days after laying their eggs. Still, he acknowledged that seeing so many dead fish can be disconcerting.

"When they do start to spawn and die, you can see a lot of them dead at once."

In 2015, scores of the fish came ashore in and around Kelly Point Park in Portland. Jones said they tend to show up every three to five years.

Smelt were listed as threatened under the Endangered Species Act in 2010 due to changes in habitat and climate, but their numbers have increased since then. While they are still a listed species, they have rebounded enough that the state occasionally opens recreational fishing for smelt.

And Jones added that smelt play an important role in the ecosystem, gathering up nutrients while out at sea and then depositing them along the rivers after they die.

"It's completely natural and normal," said Jones. "It happens and has happened for a very long time."