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
U.S. Fish and Wildlife Service Northeast Region 