Secrets of the Lower Great Lakes: The search for lake sturgeon

Catherine Gatenby is a fish biologist with the U.S. Fish and Wildlife Service.

Lake sturgeon nearly disappeared from the Great Lakes 100 years ago. Discovering the secrets of their biology to help recover the species is a group effort. Today, Catherine Gatenby takes us on a journey to the Niagara River, Lake Erie and Lake Ontario with fish biologists who are diving deep into sturgeon waters to find answers we need for helping this ancient species of fish.

Out on Lake Erie in search of lake sturgeon. Photo credit: USFWS

While the quest for lost treasure chests of information about lake sturgeon might not be considered fodder for an Indiana Jones movie, the discoveries may be more valuable than gold to fish biologists. The U.S. Fish and Wildlife Service’s Lower Great Lakes Fish and Wildlife Conservation Office and Northeast Fishery Center along with the New York State Department of Environmental Conservation, the U. S. Geological Services and Shedd Aquarium are working together to recover lake sturgeon.

Their pursuit to uncover the secrets of this ancient fish doesn’t include excursions into dark caverns or midnight camel rides across the desert. However, it does involve dives into the blue waters of the Niagara River and breathtaking adventures on the expansive Great Lakes.  It takes a dedicated team of scientists, engineers, boat captains and barge operators to restore lake sturgeon and its habitat. 

Lower Great Lakes Fish and Wildlife Conservation Office and Northeast Fishery Center lake sturgeon restoration crew out on Lake Ontario. Photo credit: USFWS

Far less is known about the lake sturgeon in lakes Erie and Ontario than in the other Great Lakes. Questions we ask ourselves as we embark on this adventure include: How many sturgeon live here? Where do lake sturgeon spend their lives? Where is the best habitat for spawning and feeding? What do they eat? How many adults are reproducing? And the ultimate question we aim to answer is: How long before we can consider the population healthy and self-sustaining in the Great Lakes? 

“We collect valuable information by tagging wild fish. We learn about their movement, diets, hormone levels and genetic diversity to help us answer these questions,” says Dr. Dimitry Gorsky, of the Lower Great Lakes Fish and Wildlife Conservation Office. 

Fish biologists with the Northeast Fishery Center and the Shedd Aquarium in Chicago, Illinois, implant a tag that will transmit valuable information on migratory behaviors of lake sturgeon. Photo credit: Shedd Aquarium

Biologists are observing an increase in lake sturgeon numbers in many remnant populations across the Great Lakes. “Over the past four years, we have captured and uniquely marked over 600 individual fish. We used to catch between 15 to 20 fish per year just 10 years ago,” reports Dr. Gorsky, “but we are steadily capturing more lake sturgeon, more than 100 fish each year. This summer, we have already captured nearly 200 fish and are on our way to a record year.”  

Northeast Fishery Center biologist releases a wild lake sturgeon after collecting vital information that will help evaluate overall health of the population. Photo credit: USFWS

The age distribution of lake sturgeon are eerily similar among different populations as those observed in the lower Great Lakes; most are less than 25 years old, suggesting that this ongoing recovery is in response to large-scale actions that took place many years ago. The first of which may be the Clean Water Act of 1972, which set the table for preventing and removing pollution from our waters. Also in the 1970s, some U.S. states along with the Province of Ontario, Canada, enacted fishing closures on lake sturgeon to protect what fish were remaining, according to Gorsky.

“For species that delay reproduction, such as the the lake sturgeon which doesn’t reproduce until at least 10 to 15 years of age, it would naturally take decades to see an increase in population growth, assuming the causes for the decline have been abated,” says Dr. John Sweka of the Northeast Fishery Center. 

U.S. Fish and Wildlife Service fisheries biologists study the gentle and ancient lake sturgeon to help with its recovery. Photo credit: USFWS

The combination of setting harvest limits and improvements in water and habitat quality is creating a favorable environment for lake sturgeon recovery. “It’s amazing that actions begun so long ago continue to be linked to improvements in our Great Lakes,” remarked Dr. Gorsky. “Perhaps the greatest secret lake sturgeon may have revealed to us is that recovery takes time.” 

Lake sturgeon in the Niagara River. Photo credit: USFWS

Read more about the U.S. Fish and Wildlife Service’s high-tech tracking of lake sturgeon in the Buffalo Harbor, NY.

Read more about the Lower Great Lakes Fish and Wildlife Conservation Office and the Northeast Fishery Center

Setting the stage for sturgeon

Zy Biesinger is a fisheries biologist for the U.S. Fish and Wildlife Service.

As the sun rises over the Seneca River in western New York, the U.S. Fish and Wildlife Service prepares to build an underwater spawning stage for lake sturgeon. Today we hear from fish biologist, Dr. Zy Biesinger of the Lower Great Lakes Fish and Wildlife Conservation Office about the collaboration on this project to help recover lake sturgeon in the Seneca River.

 

 

Lake sturgeon swimming in its natural habitat. Photo credit: USFWS

Lake sturgeon are one of New York’s largest freshwater fish and nearly disappeared from the region in the early 1900s. Some good news is that we are beginning to see signs that the species is recovering thanks to environmental protections put in place by the state, but sturgeon numbers still remain far below historical levels. One reason for persistently low population size is limited access to suitable spawning reef habitat. Lake sturgeon need fast flowing water over a clean rocky bottom for successful spawning.

Sturgeon must swim around the island to reach spawning habitat. Photo credit: USFWS

Adult lake sturgeon return home to the theatres of their birth to spawn. Like staging a performance, the males congregate together along rocky shoals of fast flowing water in preparation for spawning:  a behavior we call “staging.”  Lake sturgeon swimming up the river must choose which arm, east or west, to continue their upstream migration where the river flows around an island. Instinct tells them to follow the faster flowing water, which they do. Unfortunately that leads to an impassable dam that regulates the river’s flow from Cayuga Lake, restricting their access to suitable spawning habitat.

The dam below Cayuga Lake impedes sturgeon migration to their spawning grounds. Photo credit: USFWS

In a move to try and solve this problem for spawning sturgeon we joined forces with the New York Department of Environmental Conservation, New York State Canals Corp., the U.S. Geological Survey and the Finger Lakes-Lake Ontario Watershed Protection Alliance to create a “stage” for them – a spawning reef – located below the dam in the Seneca River.

A tug boat pushes a barge loaded with rock through the lock. Photo credit: USFWS

And that’s where we come in, actively creating spawning habitat. To choose the best location for constructing the spawning reefs, we mapped three important characteristics of suitable habitat for lake sturgeon. First, we used sidescan sonar to map the river bottom and get pictures of the mix of mud, rubble, and woody debris that can comprise spawning areas. Then we used multibeam sonar to map the changes in river depth. We also mapped water flow using an acoustic doppler current profiler.

Fish biologist Betsy Trometer assesses habitat on the river. Photo credit: USFWS

With all this information in hand we identified three viable sites to sustain sturgeon-spawning activity.  Last fall, we added 1200 tons of stone covering half an acre and built three sturgeon-spawning reefs.

A crane distributes 1200 tons of rock to create spawning reefs in the river. Photo credit: USFWS

Projects like this one are an important tool and strategy for recovering lake sturgeon, which formerly were found in the wide geographical expanse from Canada to Alabama.  Sturgeon spawning habitat enhancement projects have been very successful in other rivers, such as the Detroit and St. Clair Rivers along the Lake Huron-Erie corridor and the Saint Lawrence River.
As expected, lake sturgeon returned to the Seneca River this spring during spawning season. We are hopeful that the lake sturgeon will use the reefs as we anxiously await the fall months when we have completed our evaluation of the number of young larval fish found in the area.

 

More stories on lake sturgeon spawning habitat in the St. Clair and Detroit Rivers.

Learn more about the Lower Great Lakes Fish and Wildlife Conservation Office

Learn more about lake sturgeon