As many as 200 sturgeon were stranded in Sturgeon Lake on Sauvie Island Monday after water levels dropped and left the fish cut off from the main body of water and isolated in a shallow muddy pool, officials said.

A nearby resident first noticed the distinctive fins of the large fish, whose evolutionary characteristics date back more than 200 million years, in a pond that was separated from the rest of the lake by a vast mud flat, said Rick Swart, a spokesman for the Oregon Department of Fish and Wildlife.

The agency rented a pump and began putting water into the pond where the fish were trapped, both to raise the water level to give the animals a means to escape and also to raise the oxygen levels in the water.

“We’re hoping to buy the fish some time,” Swart said.

Hundreds of sturgeon are stuck in a shallow part of Sturgeon Lake on Sauvie Island. Officials say this is likely due to extremely low river levels. It's just a few inches deep here, but the fish have dug themselves a deeper area of water to hang in for the time being. #LiveOnK2 pic.twitter.com/gHo6n7YaVb — Keaton Thomas (@keaton_thomas) March 18, 2019

With high tides overnight Sunday, Swart said officials thought that up to half of the fish might have escaped, but there were still 20-30 visible fins in the water Monday morning, with an unknown number of fish beneath the surface.

“It’s better,” Swart said. “But it’s still not good.”

Swart said the agency was considering all options to try to save the fish — including the use of airboats or physically removing the animals and transporting them to deeper water — but the situation was complicated due to “waist deep” mud that surrounded the pool where the sturgeon were trapped.

Swart called the fish “survivors,” noting their long evolutionary history and the fact that they can go into a torpor-like state to conserve energy when in crisis. He also cautioned the public to stay away from the area as thousands of sensitive migratory birds call the Savie Island natural area home this time of year.

Officials are hoping the pumps will keep the fish alive until the next high tide when they’ll have another chance to escape.

“They need some help,” Swart said. “Whether it’s from mother nature or us, I’m not sure, but they need some help.”

-- Kale Williams

kwilliams@oregonian.com

503-294-4048

@sfkale

Visit subscription.oregonlive.com/newsletters to get Oregonian/OregonLive journalism delivered to your email inbox.