Critters of North Idaho: White Sturgeon
If you explore the rivers of the Idaho Panhandle, chances are that you might spy a trout, catfish, or maybe even a northern pike. You might have an encounter with a lamprey. But if you’re really fortunate, you might come across the largest and one of the oldest residents of Idaho’s waterways: the white sturgeon.
The white sturgeon (Acipenser transmontanus) is a monster among freshwater fishes. At full size, measurements of 12 to nearly 20 feet in length are common, and they can weigh as much as 1,388 pounds! Little wonder then that these are the largest freshwater fish in North America, the seventh largest in the world.
Interestingly, it is its cousin, the beluga sturgeon of the Caspian and Black Sea, that takes the prize for largest freshwater fish of all; it rivals even the great white shark in size, maxing out at over 3,400 pounds in weight! The white sturgeon’s long, cylindrical body is pale gray on top with an even paler underside. It does not possess scales. Instead, it has five rows of scutes running down its body that protect it from predators. Not that it has many! Its size alone keeps it safe from most would-be attackers.
But how do white sturgeon reach such massive sizes? The answer has to do with their incredibly long lifespan. These fish commonly live 80 years or so, but they often exceed this at up to 100 years. They never stop growing throughout their long lives, turning them into true river monsters.
But don’t worry; sturgeon do not attack people, and they prefer to eat smaller fish, like anchovies, shad, salmon, and lamprey. Not only do these fish live for a long time, but their lineage is quite long as well. Sister species of the white sturgeon have been found as fossils alongside dinosaurs such as Tyrannosaurus and Triceratops. It is little wonder then that some people refer to sturgeons as “living fossils.”
White sturgeon don’t start out as giants, though. Their life begins in inland rivers, after their parents congregate upstream in order to reproduce. A pregnant female sturgeon will release thousands of eggs into the water, which the males fertilize. Unlike salmon, white sturgeon do not die once the breeding season has ended, and while they may choose to migrate back to nearshore ocean waters, many remain in freshwater until it is time to breed again. These long-lived fish can afford to live a very relaxed lifestyle!
Even though white sturgeon as a whole are very common, some populations are under threat and classified as endangered. Even after closing operation in 1975, Libby Dam has had a negative effect on white sturgeon populations of the Kootenai River.
The dam’s presence has forced the fish to spawn in areas with a sandier river bottom than they are used to. This is problematic because white sturgeon eggs are adhesive. This is usually a helpful adaptation that keeps the eggs stuck to a suitable place on the bottom of the river.
But the sand in the Kootenai River’s white sturgeon spawning grounds doesn’t stay in one place, meaning that the sticky eggs get covered in sand grain and float off downriver, where they perish. Habitat loss, land and water pollution, and overharvesting of the fish and their eggs also post a threat to the fish’s survival.
Thankfully, work is currently being done by the Kootenai Tribe of Idaho to manage the rate of water flow coming from Libby Dam to ensure that the fish have suitable, less sandy places to reproduce.
We can also help by not littering Idaho’s waterways with debris and toxins, giving the sturgeon a healthy habitat in which to live. If you like to fish, be sure to follow the state’s fishing guidelines and only to fish in areas sanctioned to do so. If we all do our part, we can help sturgeons continue their ancient lineage into the future.
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