ECOS Guide to the Ecology of the Northern Rockies

Name: Polyodon spathula - Paddlefish

Family: Polydontidae (Paddlefish)

Order: Acipenseriformes (Sturgeons and Paddlefish)

Class: Osteichthyes (Bony Fishes)

Abundance: Uncommon.

Origin: Native.

Active Season: Year Round

Size:

average: 37 inches
largest: 77 inches

Colors: white-gray.

General Description: Paddlefish, sometimes called "spoonbill cats" are ancient fish. In fact, some paddlefish fossils discovered near the Fort Peck Reservoir in Montana are 60 million years old! They have been reported to weight up to 150 pounds, and can live for 50 years. They have cartilaginous skeletons, a long snout, very few scales, a large plate covering their gills, and a portion of their backbone looks like it extends into their tail fin.

Similar Species: Paddlefish are relatives of sturgeon, but they are very distinctive. No other fish species has a long paddlelike snout and prominent gill covers.

Life History: Typically, female paddlefish become sexually mature when they are about 16 or 17 years and spawn every three years, while males become sexually mature when they are 9 or 10 and spawn every two years. In the late spring and early summer, adults migrate up the Mississippi and Yellowstone rivers and deposit their eggs over gravel bars and fine substrate. When the eggs hatch, the small paddlefish are translucent and form schools. Young paddlefish are paddle-less, but they soon develop a paddle that is half the length of their body. As they grow, however, their paddle grows more slowly than their body.

Distribution: Paddlefish are found in the Mississipi and Missouri river drainages throughout the central United States. In Montana, paddlefish are found in Fort Peck Lake, the Missouri River, and the Yellostone River.

Habitat Description: Paddlefish are found in reservoirs or slow moving rivers and are able to tolerate cloudy water.

Feeding Habits: Adult paddlefish are filter feeders: they swim with their mouths open, and cathch zooplankton, aquatic insects and small fish. Interestingly, their paddle is thought to stabilize them when they are filter feeding, as swimming with an open mouth could drag the fish down. In fact, adult paddlefish that are missing their paddle are not very effective feeders, and often have low body weights. Stabilizing the fish is not the only function of the paddle, though. Both the paddle and the gill covers have tiny sensory pores on them that are thought to detect food. As well, studies have shown that the paddle may also be used to detect low frequency electric currents, which may help them feed in murky waters. Young paddlefish do not immediately start filter-feeding. Instead, they try to "bite" food, and as they grow, begin swimming with their mouths open.

Enemies & Diseases: In their early stages of development, juvenile paddlefish are preyed on by other fish.

Did You Know: Currently, paddlefish are considered to be a "species of special concern" in Montana, and there are only six reproducing paddlefish populations in the United states. However, populations are big enough to allow a fishing, but the age and sex of captured individuals is carefully monitored to ensure that the population is stable. Historically, individual paddlefish were known to travel up to 1200 miles, but now they are restricted to certain areas by dams. Interestingly, the paddlefishes closest relative is the Chinese swordfish.

Glossary:

Cartilaginous: Made of cartilage; a translucent, elastic tissue.
Spawn: to deposit eggs.
Zooplankton: Very small animals that live in the water.

Keywords: threatened

References:

American Fisheries Society, Montana Chapter. Species of Special Concern. http://www.fisheries.org/units/AFSmontana/SSCpages/SSC.htm

Holton, G. D. and H. E. Johnson. 2003. A Field Guide to Montana Fishes, Third Edition. Montana Fish, Wildlife & Parks, Helena, MT.

Montana Fish, Wildlife, and Parks Animal Field Guide. Paddlefish. http://fwp.mt.gov/fieldguide/detail_AFCAB01010.aspx.

Wilkens, L. A., Russel, D. F., Pei, X., and C. Gurgens. 1997. The paddlefish rustrum functions as an electrosensory antenna in plankton feeding. Broceedings: Biological Sciences 264: 1723-1729.

Contributor:

Allison Greene


Home Plant Guide Insect Guide Bird Guide Mammal Guide Geology Guide Fish Guide Fish by Name Fish by Family Fish by Order Glossary of Fish Terms Amphibian Guide Reptile Guide Habitats Descriptions Maps Contributors ECOS Home		Physical Characteristics - General Description - Similar Species - Life History - Distribution - Habitat - Feeding Habits - Did You Know - Glossary - References Name: Polyodon spathula - Paddlefish Family: Polydontidae (Paddlefish) Order: Acipenseriformes (Sturgeons and Paddlefish) Class: Osteichthyes (Bony Fishes) Abundance: Uncommon. Origin: Native. Active Season: Year Round Size: average: 37 inches largest: 77 inches Colors: white-gray. General Description: Paddlefish, sometimes called "spoonbill cats" are ancient fish. In fact, some paddlefish fossils discovered near the Fort Peck Reservoir in Montana are 60 million years old! They have been reported to weight up to 150 pounds, and can live for 50 years. They have cartilaginous skeletons, a long snout, very few scales, a large plate covering their gills, and a portion of their backbone looks like it extends into their tail fin. Similar Species: Paddlefish are relatives of sturgeon, but they are very distinctive. No other fish species has a long paddlelike snout and prominent gill covers. Life History: Typically, female paddlefish become sexually mature when they are about 16 or 17 years and spawn every three years, while males become sexually mature when they are 9 or 10 and spawn every two years. In the late spring and early summer, adults migrate up the Mississippi and Yellowstone rivers and deposit their eggs over gravel bars and fine substrate. When the eggs hatch, the small paddlefish are translucent and form schools. Young paddlefish are paddle-less, but they soon develop a paddle that is half the length of their body. As they grow, however, their paddle grows more slowly than their body. Distribution: Paddlefish are found in the Mississipi and Missouri river drainages throughout the central United States. In Montana, paddlefish are found in Fort Peck Lake, the Missouri River, and the Yellostone River. Habitat Description: Paddlefish are found in reservoirs or slow moving rivers and are able to tolerate cloudy water. Feeding Habits: Adult paddlefish are filter feeders: they swim with their mouths open, and cathch zooplankton, aquatic insects and small fish. Interestingly, their paddle is thought to stabilize them when they are filter feeding, as swimming with an open mouth could drag the fish down. In fact, adult paddlefish that are missing their paddle are not very effective feeders, and often have low body weights. Stabilizing the fish is not the only function of the paddle, though. Both the paddle and the gill covers have tiny sensory pores on them that are thought to detect food. As well, studies have shown that the paddle may also be used to detect low frequency electric currents, which may help them feed in murky waters. Young paddlefish do not immediately start filter-feeding. Instead, they try to "bite" food, and as they grow, begin swimming with their mouths open. Enemies & Diseases: In their early stages of development, juvenile paddlefish are preyed on by other fish. Did You Know: Currently, paddlefish are considered to be a "species of special concern" in Montana, and there are only six reproducing paddlefish populations in the United states. However, populations are big enough to allow a fishing, but the age and sex of captured individuals is carefully monitored to ensure that the population is stable. Historically, individual paddlefish were known to travel up to 1200 miles, but now they are restricted to certain areas by dams. Interestingly, the paddlefishes closest relative is the Chinese swordfish. Glossary: Cartilaginous: Made of cartilage; a translucent, elastic tissue. Spawn: to deposit eggs. Zooplankton: Very small animals that live in the water. Keywords: threatened References: American Fisheries Society, Montana Chapter. Species of Special Concern. http://www.fisheries.org/units/AFSmontana/SSCpages/SSC.htm Holton, G. D. and H. E. Johnson. 2003. A Field Guide to Montana Fishes, Third Edition. Montana Fish, Wildlife & Parks, Helena, MT. Montana Fish, Wildlife, and Parks Animal Field Guide. Paddlefish. http://fwp.mt.gov/fieldguide/detail_AFCAB01010.aspx. Wilkens, L. A., Russel, D. F., Pei, X., and C. Gurgens. 1997. The paddlefish rustrum functions as an electrosensory antenna in plankton feeding. Broceedings: Biological Sciences 264: 1723-1729. Contributor: Allison Greene