Paddlefish
Polyodon spathula (Walbaum, 1792)

member of the Paddlefish Family (Polyodontidae)

Chippewa River near Carryville, Wisconsin 1 September 1998

photos by Konrad Schmidt


Name


Habitat


Size/Age

Food

Predators

Reproduction

Conservation

 

 

 

 

What's In a Name?
Paddlefish a.k.a. Spoonbill: from its snout that looks similar to that of a paddle

Polyodon
:
(Polly´-oh-don) means "many toothed" in Greek
spathula: (spat´-you-lah) from "spatula", referring to the shape of its snout

       

   

Where Do They Live?
Paddlefish currently inhabit the lower St. Croix River and the Mississippi River below the Ford Dam. They used to be much more abundant in these rivers than they are now, and they used to occur in the Minnesota River up to Mankato. Paddlefish prefer large rivers and riverine lakes (places where rivers spread out and become more like lakes--Lake Pepin and Lake St. Croix are examples) that are deep and wide. They often are found with sturgeons, catfishes, carpsuckers, buffaloes, and common carp.

"Cool Fact": The paddlefish is a species of ancient origins. It shares several characteristics with sharks such as a spiral valve in its intestine, gills inside of spiracles on its head, and a lot of cartilage in its skeleton.

       

   

How Big Do They Get?
How Long Do They Live?
Paddlefish may be among the fastest growing fish in North America rivers. Records show them reaching 732 mm (almost 29 in) in one year. In Minnesota, they eventually grow to be 1.2-1.3 m (48-52 in) long and reach 13.6-22.6 kg (30-50 lbs). Many years ago one weighing more than 91 kg (200 lbs) was reported from Lake Okobji in Iowa. Paddlefish are hard to age accurately beyond 9 or 10 years. So, we often do not get age information for large fish. We know they live for at least 20 years and suspect they live much longer than that.

       
    What Do They Eat?
The size of paddlefish suggests that they might be great piscivores (fish-eaters). In reality they are planktivores (eaters of microscopic plants and animals floating in the water). They are the biggest planktiore in Minnesota. A paddlefish uses special sensors in its long, paddle-like snout to detect tiny electrical currents created by groups of plankton (the microscopic plants and animals). It opens its huge mouth and swims forward straining the water through its gill rakers. In this way, it consumes huge amounts of plankton each day and grows to its enormous size.
       
   

What Eats Them?
We do not know much about young paddlefish and so we are not sure what eats them. Because of their great size, adult paddlefish have few predators. Their greatest predator today is the chestnut lamprey. Lampreys do not consume entire paddlefish, (read about the chestnut lamprey) but they can weaken one and in extreme cases may case death. As many as 30 lampreys have been found attached to a single paddlefish. In the late 1800s and early 1900s, humans were by far the greatest predators of this fish. Today, paddlefish are protected from commercial and sport takes in Minnesota.

       
   

How Do They Reproduce?
Female paddlefish do not mature until they are 9-10 years old and do not spawn every year. Males mature at about 7 years old. Spawning starts in the early spring when water temperatures reach about 10° C (50° F) and water levels are on the rise from snowmelt and spring rains. Like sturgeon, paddlefish migrate from lakes and rivers into streams in search of gravel bars in water 3 m (10 ft) or less deep. As far as we know, they make no nests. Instead they swim over the gravel in groups and release their eggs and sperm. Once they are done spawning, the parent fish go back to the lake or river from which they migrated. A single female can lay a huge number of eggs300,000 to 600,000, depending on her size and age. We know nothing about the early life history of this species in the wild, other than we occasionally find larvae drifting in streams in late April and early May.

       
   

Conservation and Management
Like lake sturgeon, paddlefish were very abundant in Minnesota during the late 1800s and early 1900s. They have declined to their low numbers today because of over-fishing and changes to their habitat. At the turn of the previous century, commercial fishers could take over 454 kg (1,000 lbs) of paddlefish from Lake Pepin in a single collection! We think that paddlefish populations continue to decline today because dams and other barriers interfere with their migration, and polluted streams interfere with embryonic and larval development. Also their long life cycle makes it hard for populations to recover quickly.

 

 


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Permission is granted for the non-commercial educational or scientific use of the text and images on this Web document. Please credit the author or authors listed below.

Photographs by Konrad P. Schmidt
Text by Nicole Paulson & Jay T. Hatch in cooperation with
the Minnesota Department of Natural Resources' MinnAqua Aquatic Program

This page developed with funds from the
MinnAqua Program (Minnesota Department of Natural Resources, Division of Fisheries)
and the
Sport Fish Restoration Program (Fish and Wildlife Service, US Department of the Interior)

Maintained by Jay T. Hatch
General College and James Ford Bell Museum of Natural History
University of Minnesota, Minneapolis/St. Paul


Last updated 23 October 2002