Scientists study the green sturgeon

Scientists study the green sturgeon
Erick Van Dyke, managing fish biologist for the Oregon Department of Fish and Wildlife, handles a green sturgeon netted off the Pacific coast as part of a research project. Scientists are collecting and tagging green sturgeon to gain a better understanding factors key to survival of these fish, which are listed as threatened under the Endangered Species Act.

From the Oregon Department of Fish and Wildlife

Scientists hope to shed new light on an ancient fish in a study taking place at multiple locations along the Pacific coast.

Biologists from the Oregon Department of Fish and Wildlife, in collaboration with their counterparts from Washington, are trying to gain a better understanding of one of the region’s unique and poorly understood fish – green sturgeon.

Green sturgeon, which are listed as “threatened” under the federal Endangered Species Act (ESA), are known to inhabit waters from Northern California to Alaska. Beyond that, scientists don’t know much about what they do through much of their life cycle.

“There’s not a lot of population information about green sturgeon,” said Erick Van Dyke, leader of ODFW’s green sturgeon project.

Funded by a grant from the National Marine Fisheries Service, Van Dyke and his team will spend the next two years tracking sturgeon as they move up and down the Pacific coast and into estuaries along the way. Through their research they hope to gain a better understanding of abundance, distribution, critical habitat needs, spawning activity, and other factors key to the survival of green sturgeon.

For the next two months scientists, aided by commercial fishermen, will collect green sturgeon at the mouths of the Umpqua and Columbia rivers as well as Gray’s Harbor and Willapa Bay. Using commercial fishing boats and 600-foot gillnets, they will catch and tag up to 525 green sturgeon a year. Tags will be implanted using surgical methods and thus will not be visible to plain view. Tagged fish will provide information needed to more effectively estimate population size and to track their movement and use of estuaries along the Pacific coast line. Scientists want to find out when the fish enter the river from the ocean, how far up the river they move, how long they stay there and when they leave. They know that green sturgeon spend time in the brackish water of the river mouths but at some point move upstream to spawn in fresh water.

Scientists already know green sturgeon spawn in the Sacramento, Klamath and Rogue rivers and they suspect the fish may also be using other water bodies, like the Umpqua River, for this purpose.

Ultimately biologists are looking for information that will lead to better management and, ideally, delisting of the species, according to Van Dyke.

Green sturgeon are found only on the Pacific coast of North America. As an ESA-protected species, retention of green sturgeon is not allowed and, if caught, they must be released unharmed. Unlike the more abundant white sturgeon, green sturgeon are less likely to bite traditional fishing baits, which is why researchers are using gillnets to collect their sample populations.