Biologists from the California Department of Fish and Wildlife (CDFW) recently saved a Sacramento River green sturgeon trapped in the Fremont Weir. The five-and-a-half-foot long fish was stranded in the nearly two-mile-long concrete weir when Sacramento River floodwaters receded. Sturgeon in this area are migrating up the Sacramento River to spawn above Red Bluff.
Sacramento River green sturgeon were listed as threatened by the National Oceanic and Atmospheric Administration (NOAA) under the Endangered Species Act in 2006.
“Rescuing adult fish is always important, but because this year’s high flow conditions are optimal for sturgeon, every sturgeon saved is in a good position to spawn,” said CDFW Fisheries Branch Chief Kevin Shaffer. “Every rescue contributes to a brighter future for the species.”
Captured on March 15, the sturgeon was estimated at more than 125 pounds and over 50 years of age. Its large size required biologists to encircle it with a net rigged to poles. It was caught by slipping a hoop net over its head and unraveling a sock-like netting down the length of its body to subdue it. The fish was then placed in a specially-designed cradle for transport back to the main channel of the Sacramento River. Biologists took DNA samples, surgically implanted a sonic tracking tag and measured it prior to releasing it.
Rescuing breeding adults is vitally important to the future of the green sturgeon population. This individual’s opportunity to spawn in the future supports the genetic diversity and integrity of the population. Over the last few years, a number of green sturgeon have been acoustically tagged in the greater Sacramento-San Joaquin River system and are being tracked to better estimate population size, distribution and migration patterns.
Recent efforts to assist green sturgeon appear to be helping, according to NOAA green sturgeon recovery coordinator Joe Heubleib. He recently stated that he is “cautiously optimistic” that production may start to increase with improvements to spawning habitat accessibility.
Under Governor Edmund G. Brown Jr.’s “California Eco Restore” initiative, a $4.5 million construction project to improve Fremont Weir is slated to start this summer. The changes will improve fish passage back to the Sacramento River as bypass flows recede, reducing the risk of stranding for endangered and threatened salmon and sturgeon.
Recent rescue efforts have saved green and white sturgeon, young fall-, winter- and spring-run Chinook salmon, young and adult steelhead, a lamprey, two species of bass and a host of other native fish.