The U.S. Army Corps of Engineers team rescued a 6-foot white sturgeon during the annual maintenance pump out at the Ballard Locks earlier this month.
Each year, Corps natural resource and maintenance staff, fish biologists, scientists and volunteers go on a fish-rescue mission when the locks are drained.
Although de-watering is done during low tide, some fish and other marine life are sometimes captured in the chamber when the lock gates are closed.
To ensure Endangered Species Act listed fish are safe, the team must capture, haul them out of the 50-foot-deep chamber and release them. The team doesn’t limit its efforts to ESA listed species and this year the rescue included an estimated 100-pound sturgeon.
“Sturgeon have been observed infrequently in Lake Washington over the years,” said Corps fish biologist Dr. Fred Goetz. “Most likely the fish would have passed through the Locks to get to the lake.”
According to Goetz, as a group, coastal white sturgeon do not migrate through marine waters as widely as green sturgeon, which are ESA listed.
Upon finding the fish, the team immediately called on NOAA Fisheries sturgeon ecology expert Dr. Mary Moser. She went to the locks, verified it was a white versus green sturgeon and provided tips to the team on “successfully capturing and releasing the beast.
It took the team about an hour to capture and release the sturgeon.
“The Corps’ team did a great job putting together such a quick and successful rescue,” Moser said.
A scan did not find a Passive Integrated Transponder, or PIT tag, but the team took a DNA sample. Moser will run a test from the sample to identify if this sturgeon originates from the Columbia or Fraser River.
There is no white sturgeon season in Lake Washington but they are found in greater abundance in the Skagit, Stillaguamish and Snohomish Rivers where they can be caught, said Goetz.
Sturgeon date back to prehistoric times and are the world’s largest freshwater fish, growing up to 20 feet long and weighing more than 1,000 pounds. An 8-foot-long specimen was found dead in Lake Washington in 2013 and another 5 1/2-foot-long sturgeon was inadvertently netted and released by a University of Washington research team in 2005.
A 1987 photo also exists online of an 11-foot, 900-pound, female white sturgeon that had lived in Lake Washington before she died of what researchers said were natural causes. They estimated she could have been between 80 to 100 years old.
In addition to the usual flounder, crab, anemone and starfish, the team has also rescued river otter and seals in the past.
The most unusual rescue? A wedding ring found and returned to the original owner who dropped it while tending lines on the couple’s boat locking through.
Photo courtesy of the U.S. Army Corps of Engineers.