Paddlefish

Polyodon spathula

padfishill_jt.jpg

illustration of big, long-nosed fish
Joe Tomelleri
Family

Polyodontidae (paddlefishes) in the order Acipenseriformes (sturgeons and paddlefishes)

Description

Sharklike, with a greatly elongated paddlelike snout. Bluish-gray to blackish on back, grading to white on belly. Snout in small individuals is more 1/3 of the fish’s total length. Mouth is large, lacks teeth (in adults) and is far back beneath the head. Eyes small, just above the front edge of the mouth and directed down and forward instead of to the side. Gill cover has a fleshy, pointed flap. Tail is forked, the upper lobe longer than the lower. No scales, except for a patch on the tail.

Size

Length: to about 7 feet; weight: to 160 pounds or more.

paddlefish_swimming.jpg

Swimming paddlefish
Paddlefish
Paddlefish, also known as spoonbill, have long, paddle-shaped rostrums that are about one-third the length of their bodies.

FG-0032_Paddlefish.mp4

Video of paddlefish.
Habitat and conservation

Paddlefish live mostly in open waters of big rivers, swimming continuously near the surface, and likely don’t have a specific home range. As waters rise in spring, paddlefish move upstream to gravel bars to spawn. Because they need lots of open, free-flowing rivers plus oxbows and backwaters for feeding and gravel bars for spawning, paddlefish numbers have declined with stream channelization, levee construction and drainage of bottomlands. Overharvesting has also contributed to their decline.

Foods

Paddlefish swim slowly through water with their mouths wide open, collecting tiny crustaceans and insects in their elaborate, closely set gill rakers.

image of Paddlefish distribution map
Distribution in Missouri

Historically found in the Mississippi, Missouri and Osage rivers, and other streams; now stocked in impoundments.

Status

Channelization, damming, impoundments and other river modifications have greatly diminished the habitat for this fish. Impoundments hold the highest populations of paddlefish today, but because many of these lack feeder rivers that meet the fish’s exacting spawning needs, these populations are not self-sustaining and must be stocked. The closest relative, the Chinese paddlefish, has recently become extinct.

Life cycle

Spawning occurs in late spring at times of high water; eggs are deposited on silt-free gravel bars where, during regular water levels, they would be exposed to air or are covered by very shallow water. The eggs hatch and the larval fish are swept downstream to deeper pools where they grow to adulthood. Paddlefish can attain a length of 10 to 14 inches their first year, and at age 17 can be 60 inches long. Paddlefish can live to be 30 years old or more.

Human connections

Missouri’s official state aquatic animal, it is highly valued as a sport fish. It is valued for its flesh as well as for its caviar. Because it is one of the most ancestral fish species alive today, it is of considerable interest to biological research.

Ecosystem connections

The constant grazing of these fish on tiny aquatic organisms helps to keep their populations in check; paddlefish and their eggs and fry provide food for other aquatic predators.