Return of the Lake Sturgeon

Dr. Dawn Dittman, a research ecologist with the U.S. Geological Survey in Cortland, poses with a previously-stocked lake sturgeon recovered from the Seneca River. Photo courtesy U.S. Geological Survey
by John Adamski

The lake sturgeon is the largest – and the oldest – freshwater fish species swimming in New York’s upstate waters. It dates back to the time when dinosaurs roamed the earth. This ancient bottom-feeding giant is covered with a dull gray, smooth and shark-like skin, which is as tough as leather. It is further protected by five rows of bony plates, called scutes, along each of its sides and on top of its back, giving it a definite prehistoric appearance.

According to the U.S. Fish & Wildlife Service, the lake sturgeon inhabits large river and lake systems primarily in the Mississippi River, Hudson Bay and Great Lakes basins, and represents an important biological component of the Great Lakes fish community. In New York, the lake sturgeon is present in the St. Lawrence River, Niagara River, Oswegatchie River, Grasse River, Lake Ontario, Lake Erie, Lake Champlain, Black Lake, and Oneida Lake, as well as in Cayuga Lake and the Seneca-Cayuga Canal in the Finger Lakes Region. But even though it may be the largest freshwater fish species in the state’s inland waters, its conservation status is threatened.

Lake sturgeon can be considered an inshore warmwater species, making it relatively easy to catch. It prefers water temperatures that range from the low 50s to the mid-60 degrees Fahrenheit, and depths between 15 and 30 feet. Using its four catfish-like barbels to feel and locate prey along the bottom and its elongated snout to stir up sediment, the lake sturgeon feeds mostly on small invertebrates such as insect larvae, crayfish, snails, clams and leeches as well as the invasive round goby. Because of its lack of teeth, the lake sturgeon uses its rubbery prehensile lips to pick up food and swallow it whole – using a method of filter-feeding similar to that of whales.

At one time, the once-plentiful lake sturgeon was considered a trash fish and a nuisance because of the damage that it caused to commercial fishing equipment. The trawling nets used for lake trout, Atlantic salmon, blue pike, and walleyes on Lakes Ontario and Erie were no match for a thrashing 5-foot long giant weighing 100 pounds or more. Considered a troublesome “by-catch” by commercial fishermen, lake sturgeon were slaughtered by the thousands and stacked like cordwood to be burned on the beaches in a consolidated effort to get rid of them.

But by 1880, the mild lobster-like flavor of sturgeon meat was finally realized, and sturgeon eggs were becoming prized as caviar. Commercial fishing for lake sturgeon quickly evolved into a major industry and by the end of the 1800s, the Great Lakes sturgeon catch totaled more than 4 million pounds per year. These high catch rates, combined with the fish’s slow rate of reproduction and a number of environmental issues, were the beginnings of a precipitous decline in lake sturgeon population numbers.

By the early 1900s, lake sturgeon populations throughout their range had been significantly reduced and even extirpated in places because of overfishing, habitat destruction, pollution and hydroelectric dam construction that blocked upstream spawning runs. Today, the species is listed as either threatened or endangered in 19 of the 20 states within its original range. This ancient fish, which has existed for 136 million years – since dinosaurs were at the height of their development – was beginning to look like it would soon be doomed to extinction. Would the species ever be able to sustain itself again?

Dr. Dawn Dittman is an aquatic research ecologist with the U.S. Geological Survey (USGS) and is stationed at the Tunison Laboratory of Aquatic Science in Cortland, New York. She is the acclaimed expert on anything to do with lake sturgeon, and has been working on restoring the species since 1999. Without exception, every conservation organization that I contacted for an interview referred me to her.

Dawn also works on American eel and walleye restoration projects, and studies the ecological impacts of invasive mussels and round gobies, a small nonnative fish that sturgeon sometimes feed on. Partner organizations that work with Dawn and the USGS on lake sturgeon restoration programs include the U.S. Fish & Wildlife Service (USFWS), the New York State Department of Environmental Conservation (DEC), and the Seneca Park Zoo in Rochester, located on the banks of the Genesee River near one of the project’s major sturgeon release sites.

I was surprised to learn that lake sturgeon is also native to Cayuga Lake, the only Finger Lake where they exist. Since Cayuga and Seneca Lakes are connected by the Seneca-Cayuga Canal, I asked Dawn why they haven’t migrated into Seneca Lake as well. She explained, “The Cayuga and Seneca Canal has four locks, with lifts of between 7 and 28 feet. The current canal use is almost entirely recreational with the locks opened relatively infrequently. The double lock in Seneca Falls would be very difficult or almost impossible for a lake sturgeon to use to move upstream.”

As part of the ongoing restoration program, young lake sturgeon are being stocked directly into Cayuga Lake on a regular basis as well.

Restoring a lake sturgeon population to a sustainable level is a slow and tedious process because of the fish’s maturity rate. Even though males can live for more than 50 years, they don’t reach sexual maturity until they’re at least 10 years old. Females reach sexual maturity at age 14 and may live to 80 years or more. Females only spawn once in a four- to nine-year period, and males spawn once every two to seven years, making the mating cycle infrequent and interrupted as well. According to the USFWS, only 10 to 20 percent of adult lake sturgeon within a specific population spawns during any given season.

Spawning takes place between late April and June with eggs being scattered loosely in stream rapids and along rocky shores. A mature female will lay anywhere from 100,000 to 800,000 eggs at a time, depending on her age and size, but only a small percentage will survive. The fry hatch within a week and quickly grow into 6- or 8-inch fingerlings before winter sets in. Fingerlings for the stocking programs are reared by the USFWS hatchery in Genoa, Wisconsin, and DEC’s Oneida Fish Hatchery in Constantia. Potential predators like muskellunge and northern pike are not inclined to pursue sturgeon fingerlings because of their bony armor-like protective skin.

One of Dawn’s duties is the scientific monitoring of lake sturgeon through sample netting after they’ve been stocked. Released fish are electronically tagged with an implanted radio chip that can be read with a scanner anytime an individual fish is recovered. In addition, a yellow streamer attached to each fish provides reporting information in the event that they’re caught or otherwise encountered by members of the public. This is a good place to remind fishermen that it’s illegal to intentionally target, catch, or keep any lake sturgeon anywhere in New York State. Any sturgeon incidentally caught must be released unharmed. See the DEC’s website for more specific information.

The biggest sturgeon success story by far is probably that of the Genesee River stocking program. At one time the Genesee ranked as one of the most polluted rivers in the country due to the combined discharges of toxic chemicals, industrial waste, urban storm water runoff, and agricultural runoff from rural areas further upstream. The river originates in Pennsylvania and flows 140 miles northward before emptying into Lake Ontario at Rochester. Along the way, it accumulates agricultural pollutants from eroded soils that contain fertilizers, insecticides, and manure runoff, which start forming a toxic brew many miles upstream even before mixing with industrial and urban contaminants as the river flows closer to the lake.

Dr. Jeff Wyatt is the head of veterinary medicine at Seneca Park Zoo, as well as a professor and the department chair of the University of Rochester’s Division of Comparative Medicine. He was also the very first person who recommended that I interview Dawn. He said, “Seneca Park Zoo veterinary staff has been assisting Dr. Dawn Dittman … with her program reintroducing and monitoring 5,000 hatchery reared sturgeon in the lower Genesee River since 2003. The oldest fish are now over 4 feet long and are expected to spawn near lower falls by 2020. These thriving, repatriated native fishes are excellent bio-indicators of an improved Genesee River health.”

Although the river cleanup efforts that are currently underway still have a long way to go, the Genesee River has already been given the thumbs-up by lake sturgeon themselves. A total of 5,400 fingerlings have been released in the river since the program began. During a recent net sampling, Dawn found that 95 percent of the sturgeon stocked the previous fall were still in the river and were doing well. It looks like they just might be able to sustain themselves after all.