Monitoring the Mississippi
numbers began to decline in the early 1900's, probably from overharvesting. Since then, habitat in the Mississippi and Missouri rivers has been greatly altered, which may account for the low numbers we see today.
The experimental trawl was originally developed to capture several species of rare big river chubs (minnows). Specifically, these included sturgeon chubs and sicklefin chubs.
Both species live only in big, turbid rivers. In Missouri, they are found only in the Missouri and Mississippi rivers.
Historical data suggests that both species declined in the open Mississippi River and in much of the Missouri River. Both species are candidates for federal listing and remain species of special concern in Missouri becausethe specific habitat they require is rare in our big rivers.
In 1991, Open River field station biologists "rediscovered" a large freshwater prawn thought to have be extinct in the Upper Mississippi River. The prawn, called the Ohio shrimp, grows large enough for humans to eat. They were once so common in the Mississippi River that they supported commercial fisheries in several small towns along the river. Many of these small towns held annual "shrimp fries."
The species began to decline sometime in the late 1930s. The last known collection of Ohio shrimp in the open Mississippi River was near Cairo, Ill., in 1962.
Discoveries like that of the Ohio shrimp suggest a lack of information about invertebrates in the Mississippi River. Furthermore, Open River Field Station biologists recently captured several larval specimens of pseudiron mayfly from a Mississippi River gravel bar. This is the first time this species has been found in Missouri's portion of the Mississippi River. New research is helping develop even better methods of sampling for big river invertebrates.
The Long Term Resource Monitoring and the Open River Field Station programs have caught the attention of river ecologists around the world. In 1993, during the biggest flood in years, scientists from Russia's Institute of Biology of Inland Waters visited the Open River Field Station.
Dr. Arthur Poddubney, head of the Department of Ichthyology, and Gregory Scherbina, from the Laboratory of Aquatic Invertebrate Ecology, toured the facility and flooded areas. During their visit, we exchanged much information about our respective programs on the Mississippi and Volga rivers.
In 1995, Peruvian biologists Enrique Rios Tsern and Norma Flores Arana of the Universidad Nacional de al Amazonia Peruana visited twice. They are responsible for "managing" the Amazon River and were interested in our procedures.
By definition, monitoring