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A close relative of the sturgeon, the paddlefish is native to the Mississippi River system, including its large tributaries such as the Illinois River. The paddlefish has been introduced as a game fish as far away as the lower Danube River in the Balkans and is farm-raised from Montana to Russia. In its native habitat, the paddlefish prefers warm rivers with sluggish currents and deep pools, oxbows, overflow lakes and the lee of islands. Its long life, up to 55 years, and large size, up to 200 pounds, are thought to be evolutionary guards against predation, along with its heavy periodic spawning, a form of predator satiation. These measures have worked quite well, judging from the species’ age. The oldest paddlefish skeleton known was found alongside a 65 million year old dinosaur.
The paddlefish’s most distinctive characteristic is its namesake shovel-shaped snout. Initial explanations theorized that the snout was used for excavating prey, until scientists realized that it is a filter-feeder, filtering plankton from the water through gill rakes. The paddle is now thought to be a sensory organ, used either in locating plankton or judging currents and river bottom topography, perhaps aiding in spawning migration.
The flesh and roe (caviar) of the paddlefish are high quality and actively sought. Though commercially and privately farmed and fished, the primary threats to the species are damming of rivers and degradation of water quality.
Nature picture credits (left to right): Paddlefish © Eric Engbretson, www.underwaterfishphotos.com; Paddlefish © Norbert Wu / Minden Pictures (closeup).
