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The Sturgeons
Nature Bulletin No. 663-A   January 21, 1978
Forest Preserve District of Cook County
George W. Dunne, President
Roland F. Eisenbeis, Supt. of Conservation

THE STURGEONS
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.

The great size and power of the lake sturgeon was one of the causes of its undoing. In early days the commercial fishermen of the Great Lakes destroyed them because they ripped and tore their nets. Later it became valuable and is now the highest-priced freshwater fish on the market. Becoming scarcer and scarcer in spite of many years of legal protection, the present annual catch from the Great Lakes is less than one percent of the amounts taken formerly.

The threatened extinction of the lake sturgeon is due in large part to its late maturity, Females do not spawn for the first time until they are over 20 years old. After that they breed at only 5 or 6-year intervals. Besides, many of the tributary streams in which they formerly spawned have been blocked by dams, choked with silt, or polluted.

That famous delicacy, caviar, is made from sturgeon roe. Those black eggs, each about one-eighth inch in diameter, are freed from the membranes of the ovary and merely treated with salt. A 14-ounce can of genuine imported Russian caviar sells for $175. The domestic product is cheaper. Russia is the world's largest producer and exporter.

In addition to the smoked flesh, several other products come from the sturgeon. The air bladders are dried to produce the isinglass used to clarify wines and beer. Oil is rendered from the fat; the gristly skeleton is made into glue. The skins can be tanned to make a fine grade of ornamental leather.

The sturgeon family of fishes has about twenty living species, all restricted to the northern hemisphere. Seven of these are found in North America: two on the Atlantic Coast; two on the Pacific Coast; and three in the inland lakes and rivers.

The largest of all American fishes is the white sturgeon of the coastal waters and rivers of the Pacific Northwest. A 12-foot female tipped the scales at 1285 pounds and others, in the past may have approached a ton. The largest sturgeon of all was a beluga from the Volga which weighed out at 3221 pounds.


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