American paddlefish

American Paddlefish

American paddlefish in natural habitat

The American paddlefish (Polyodon spathula), also known as the Mississippi paddlefish or spoonbill, is a species of freshwater fish endemic to the Mississippi River Basin in the United States. It is one of the few extant species of paddlefish, a group of ancient fish that have existed for over 300 million years.

Description

The American paddlefish is easily recognizable by its elongated, paddle-shaped snout, which can be up to one-third of its body length. This snout, or rostrum, is covered with electroreceptors that help the fish detect plankton, its primary food source. The body of the paddlefish is smooth and scaleless, with a bluish-gray coloration.

Diagram showing the general morphology of paddlefish

Adult paddlefish can grow to lengths of 1.5 to 2.2 meters (5 to 7 feet) and weigh up to 70 kilograms (154 pounds), although most are smaller. They have a heterocercal tail, similar to that of sharks, which aids in their swimming efficiency.

Habitat and Distribution

American paddlefish are found in large, slow-moving rivers and their tributaries, primarily within the Mississippi River Basin. They prefer waters with abundant plankton, which they filter feed on using their gill rakers.

Feeding

File:American paddlefish filter feeding.webm

Paddlefish are filter feeders, using their gill rakers to strain plankton from the water. They swim with their mouths open, allowing water to flow over their gills where plankton is trapped and consumed. This feeding method is highly efficient and allows paddlefish to thrive in environments where plankton is abundant.

Reproduction

Paddlefish spawn in the spring when water temperatures rise. They migrate upstream to gravel bars where females release eggs and males fertilize them externally. The eggs are adhesive and stick to the substrate until they hatch.

File:Paddlefish transformation from embryo to larval stage of development.webm

Development

After hatching, paddlefish larvae drift downstream to deeper waters where they continue to develop. Juvenile paddlefish grow rapidly, reaching lengths of 30 centimeters (12 inches) within their first year.

American paddlefish fry at 30 days of age

Conservation

The American paddlefish is considered a vulnerable species due to habitat destruction, overfishing, and pollution. Dams and other river modifications have disrupted their natural spawning migrations, leading to declines in population numbers. Conservation efforts are focused on habitat restoration and the regulation of fishing practices to ensure sustainable populations.

Related Pages

• Paddlefish
• Mississippi River
• Filter feeding
• Electroreception