Between where the Missouri River joins the Mississippi at Saint Louis, Missouri, and Cairo, Illinois, the depth averages 30 feet (9 m). Below Cairo, where the Ohio River joins, the depth averages 50–100 feet (15–30 m) deep. The deepest part of the river is in New Orleans, where it reaches 200 feet (61 m) deep.
St. Paul — The Mississippi River remains a healthy, clean stream for much of the way down to about St. Cloud, the river's most pristine stretch on its 2,320-mile journey to the Gulf of Mexico.
While there have been past “sightings,” most have turned out to be pranks or misidentifications. The reality is that the largest of the Great Lakes (Lake Superior and Michigan) are extremely deep lakes that are too cold for sharks.
Researchers have documented at least two bull shark sightings in the Mississippi River. Female bull sharks can reach up to 11 feet long and weigh 500 pounds.
Unlike most sharks, bull sharks can survive in freshwater for long periods of time. They have even been found in the Mississippi and Amazon Rivers. They prefer shallow coastal water, which means they can often come into contact with humans.
Lake Nicaragua is one of the largest freshwater lakes in the Americas and bull sharks travel up the San Juan River and through a series of eight rapids in a similar manner to salmon to reach the lake, where they may stay for several years.
But Heithaus said it would not be possible for a bull shark to reach the Great Lakes on their own because most don't travel very far upstream. If one did reach the lakes, it would not be able to survive due to the cold water temperature.
Many popular kinds of fish including bass, bream, crappie, freshwater drum, and small catfish (less that22 inches in length) are SAFE to eat. Farm-raised catfish are SAFE to eat.