Paddlefishes

Paddlefishes are a small group of large freshwater ray-finned fish in the order Acipenseriformes, typically placed in the family Polyodontidae. They are characterized by an elongated, flattened rostrum, or paddle, which they use to detect prey in murky water. The skeleton is largely cartilaginous, and they have a long, streamlined body with a heterocercal tail.

Two living species are recognized: the American paddlefish (Polyodon spathula) in North American rivers, and the Chinese paddlefish (Psephurus gladius) in the Yangtze River system. The Chinese paddlefish is believed extinct, with last confirmed records in the early 2000s.

Ecology and feeding: Paddlefishes are filter feeders; they feed on zooplankton, which they capture as water passes through specialized gill rakers. The rostrum is covered in electroreceptors that help detect prey in turbid waters.

Habitat and reproduction: They inhabit large rivers and lakes and undertake seasonal migrations to spawning grounds in spring. Maturity is reached after several years, and individuals may live for multiple decades in protected waters.

Conservation and human use: The American paddlefish is listed as Vulnerable by the IUCN due to overfishing and habitat modification. The Chinese paddlefish is likely extinct, with dams and overharvesting cited as major threats. Roe is processed into caviar, and the meat is consumed in some regions.