All stories about sea monsters do not come from sailors who saw a
strange beast a long time ago in a distant part of the world. Some start on our very doorstep. Every few years some excited Chicago vacationer babbles about a huge creature that he saw leap, splash, and beat the water into foam right in front of his eyes. This is good news. It means that the lake sturgeon is not yet extinct.
The Sturgeons are primitive fishes whose fossil history can be traced
back for fifty million years. Instead of overlapping scales, they have
five lengthwise rows of heavy bony shields and a head covered with
bony plates. The rest of the skeleton is cartilage or gristle, as in the
sharks. Also like the sharks, the spinal column continues into the upper lobe of the tail. On the underside of the snout are four fleshy barbels or feelers that drag the bottom and locate the snails, clams, crayfish, worms and insect larvae on which it feeds. Behind these is the tube-like mouth which sucks up food like a vacuum cleaner.
The lake Sturgeon is the giant of inland freshwater fishes and one of the oldest living animals in the world. The largest recorded from Lake
Michigan in recent times was killed by a boat propeller near the mouth
of the St. Joseph River in 1943. It was 7 feet, 11 inches long and
weighed 310 pounds. Another with a weight of 215 pounds was 152
years old when it was caught in 1953.
Populations of the Pallid Sturgeon are now so small that the big fish are rarely seen or caught by anglers. The primary reason for their decline is believed to be habitat loss caused by man.
Pallid Sturgeon evolved for millions of years in a natural river system. These waters had meandering, braided channels and backwaters that provided different depths and flow velocities. But today, the Pallid’s habitat is altered by dams that modify flows, reduce turbidity and lower water temperatures. The river habitats of the Missouri and Mississippi also have been altered by various channels and construction of dikes that narrow the rivers and cut-off backwater areas.
Smallest of the Sturgeon species in North America, Shovelnose Sturgeon can tolerate high turbidities and are usually found in the strong currents of main river channels. They are often found over sand and gravel substrates feeding on aquatic insects, mussels, worms, and crustaceans. Spawning normally occurs from April through early July with mature shovelnose migrating upriver to spawn over rocky substrates in flowing water between l9-21 C. Individuals mature after 5 to 7 years of age, at approximately 500 mm and 630 mm (TL) for males and females, respectively.