The data on past and present sturgeon habitat, food, and growth patterns is rather limited. The three sturgeon IDFG biologists have caught this year were each over 10 feet long. Now, however, the most recent record (set in 2016) was 117 inches and 500 lbs. They are still the largest fresh water fish in North America. Historically, caught sturgeon often weighed more than 1,000 pounds. If a population of sturgeon has only a 50-percent survival, that translates to just 2 percent being able to spawn, so these recently caught larger, older fish help support a more robust population. Those are the adult sturgeon that are able to spawn. The river is a tough world for the small and young.”īut the good news about sturgeon, and especially these big boys, is, once they get big, their survival rate increases to between 92 and 96 percent. Bass eat smolts up to 8 to 10 inches, and pike minnows eat them, too. “They live on the bottom and gobble up larvae. “Siberian prawns are in the system now,” explains DuPont. And new species are turning up in the slack water, where additional food is plentiful in these quiet waters. The Lower Granite Dam has a 37-mile-long pool behind it. However, in the larval drift stage and up to 15-inch juveniles, they are sitting ducks for predators.” “At this size, predation is basically nonexistent. “Once sturgeon reach 35 inches, they grow a lot, and survival is much better,” adds DuPont. Pre-dam days found sturgeon feasting on dying salmon as well as native lamprey, which were in the tens of thousands. Once a sturgeon reaches 35 inches, growth speeds up and clams and mussels are added to the diet. As they grow larger crayfish become part of the menu. When the fish are small-under 25 inches-they feed on insects that colonize the river bottom or burrow in the mud. Sturgeon in the Snake travel as far as Lower Granite Dam, looking for food and spawning areas. After hatching they begin the larval drift stage of development, and it’s then they are most vulnerable.” Fertilized eggs will stick to rocks, and when they first hatch, will still have a yolk sac attached. They are broadcast spawners, with eggs being released and sperm being showered over them. “Sturgeon spawn in faster water, and dams, by design, slow water in the reservoirs. The life cycle of sturgeon is a bit tricky in the age of dams, says Dupont.
“It’s hard to tell exactly how old these big fish we are catching are now, but they are certainly in the 80- to 100-year span.” “In the early 1970s, we had a moratorium of sturgeon fishing,” explains Joe Dupont, IDFG Fisheries Manager from the Lewiston office. We’re talking sturgeon of course, those amazingly long-lived denizens of the Snake River that were in the system prior to dams being built on the Columbia and Snake. And recently, Idaho Fish and Game biologists have been finding monsters over 10 feet, sizes that haven’t been seen in years. They are remnants of another age and can easily live more than 100 years. Email This article contains affiliate links.
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