Fish
Lake Sturgeon
Acipenser fulvescens · also called rock sturgeon, freshwater sturgeon
The lake sturgeon is a fish from before the dinosaurs that is still swimming in the Great Lakes, or what is left of it is. A single fish can be older than the fishery laws written to protect it, and the species is only now, after a century, beginning to climb back.
Overview
Acipenser fulvescens lives in the large lakes and rivers of central and eastern North America. It has the sturgeon’s ancient body plan: a mostly cartilage skeleton, a shark-like upturned tail, and five rows of bony scutes. It is a bottom feeder that vacuums up insect larvae, crayfish, and clams with a tube-like toothless mouth.
Old and slow
Females can live past 100 years and a few reach 150. But males do not spawn until about 15 and females until 20 to 25, and a female then spawns only once every four to nine years — so killing a big sturgeon removes decades from the population.
The collapse
Treated first as a nuisance, then hunted for flesh, caviar, and isinglass (a swim-bladder gelatin used to clarify beer and wine), the lake sturgeon fell by over 99% by about 1900, and dams then cut it off from its spawning rivers.
Status
Globally Least Concern as of 2022 and slowly increasing, but still far below historical numbers and protected as Threatened or Endangered across much of its range.
Lake Sturgeon: common questions
How long do lake sturgeon live?
Longer than almost any other freshwater fish. Females routinely live 50 to 80 years, regularly pass 100, and a small number have been aged beyond 125 by counting growth rings in a cross-section of the leading fin ray. The oldest well-documented lake sturgeon, caught in Lake Huron waters off Ontario, was estimated at around 150 years, meaning it hatched before Canada was a country. Males do not live quite as long as females. This extreme longevity is tied to slow growth, late maturity, and infrequent spawning, and it means the largest fish in a river are often more than a century old.
Why did lake sturgeon nearly disappear?
They were hit from several directions in a short time. In the mid-1800s commercial fishermen on the Great Lakes regarded sturgeon as a pest, killing them by the tonne, burning them for fuel, and even stacking them like logs. Then a market developed for smoked sturgeon, for caviar made from the roe, and for isinglass, a gelatin made from the swim bladder and used to clarify drinks, and the fishery switched to deliberate slaughter. By 1900 the catch had crashed. Dams then blocked the fish from their spawning rivers, and pollution degraded what habitat was left. A fish that needs 20 years to breed could not recover on its own.
Is it legal to catch lake sturgeon?
It depends entirely on where you are. In much of the species' range lake sturgeon are fully protected and must be released unharmed, and in some states and provinces they are listed as threatened or endangered. A few places with healthy populations run tightly controlled seasons, the best known being the winter spear fishery on Lake Winnebago in Wisconsin, where a strict quota, a registration system, and a minimum size have allowed a limited harvest to continue for decades. Anyone fishing where sturgeon occur should know the local rules, because penalties are severe.
What is the difference between a lake sturgeon and a paddlefish?
They are related, both being ancient, mostly cartilaginous fish, but they feed in opposite ways. The lake sturgeon is a bottom feeder that hunts individual prey items by touch and taste with its barbels and sucks them off the riverbed. The American paddlefish swims through open water with its huge mouth held open, filtering tiny zooplankton with fine gill rakers, and uses the long paddle-shaped snout as an antenna to detect swarms of prey. The sturgeon has bony scutes down its body; the paddlefish has smooth, nearly scaleless skin.