40 Fun Facts About Paddlefish

An adult American paddlefish can top 100 pounds while feeding almost entirely on which food, strained from the water?

Zooplankton is nearly all an adult American paddlefish eats: water fleas, copepods and other specks. Because it never bites at bait, anglers cannot tempt one with a lure.

The long paddle of an American paddlefish is covered in thousands of receptors that detect what from its prey?

Electric fields are what the paddle reads, picking up the faint signals that living animals give off. The sense is fine enough to register the leg movements of individual prey animals.

Polyodon, the genus name a French naturalist gave the American paddlefish, is Greek for which trait?

Many teeth is the meaning, yet adults have none at all. The name is thought to nod to the fine comb-like filters that strain the fish's food.

Which label is often given to the American paddlefish, the last surviving member of an ancient family?

Living fossils fits because the family goes back at least 120 million years, about as far as flowering plants. Only one species of it is left on Earth.

The American paddlefish, last survivor of its family, is native to the basin of which North American river?

Mississippi country is home, though the fish have vanished from the edges of their old range, including the Great Lakes and New York.

The American paddlefish is also known by which nickname, shared with a pink wading bird?

Spoonbill, or spoon-billed cat, is a common name for the fish along its home rivers. The paddle behind the name makes up about a third of the animal's length.

The skeleton of an American paddlefish, which has very few true bones, is made almost entirely of what?

Cartilage forms nearly the whole frame, a trait kept from the animal's earliest ancestors. It is one reason the species is described as a primitive fish.

The Chinese paddlefish, the only other paddlefish to reach modern times, was last seen in 2003 in which river?

Yangtze fishermen caught the last known one in January 2003. Surveys of the whole basin in 2017 and 2018 found none, and the species was formally declared extinct in 2022.

Which structures cut American paddlefish off from upstream spawning grounds, so many populations must be restocked?

Dams wall the fish off from the shoals where they breed. One that began operating in China in 1981 did the same to the Chinese paddlefish, which later went extinct.

Which ancient fish, also heavily poached for their roe, are the closest living relatives of the paddlefish?

Sturgeons and paddlefish split from a shared ancestor well over 100 million years ago. They remain alike enough that a lab cross between the two produced living young in 2019.

The paddlefish family dates back roughly 125 million years, to the early part of which geological period?

Cretaceous rocks in China hold the oldest known member of the family, a fish under three feet long. Its descendants went on to outlive the dinosaurs.

Because American paddlefish ignore bait and lures, sport anglers must catch them using which method?

Snagging means sweeping a large treble hook through the water on a stout rod and heavy line until it catches in the fish. A filter feeder has no reason to bite at bait.

Which US state, a pioneer of paddlefish hatcheries in the 1960s, made the fish its official aquatic animal?

Missouri honours the paddlefish as its state aquatic animal. Its conservation department took up artificial breeding mainly to keep a popular sport fishery alive.

Which invasive shellfish harm American paddlefish by competing with them for food in rivers and lakes?

Zebra mussels multiply explosively and strain so much drifting food from the water that less is left for paddlefish and for native mussels.

Unlike its American cousin's broad paddle, the Chinese paddlefish's narrow snout was shaped like which weapon?

A sword is the usual comparison, and the species was even known as the Chinese swordfish. It was a hunter, too, chasing down smaller fish rather than filtering.

The famous claim that Chinese paddlefish grew 23 feet long is thought to rest on which kind of mistake?

A translation error is the likely culprit: the figure reached English in 1943 from a Chinese paper of 1931. The last one ever caught, among the largest reliably measured, was just under 12 feet.

Before the paddle was shown to be a sense organ, scientists thought American paddlefish used it for which task?

Digging up the bottom was the old guess, along with keeping balance. Yet paddlefish that lose part of the paddle go on feeding and stay healthy, so it is no shovel.

Biologists age an American paddlefish by counting yearly growth rings, as in a tree, in which body part?

Jawbone slices show one ring per year, and they suggest some paddlefish live for 50 years or more. Females tend to outlive and outgrow the males.

Which term do biologists use for the long paddle of a paddlefish, a skull extension that is missing at hatching?

Rostrum is the anatomical term. Hatchlings start life without one, then grow a paddle that ends up about a third of their body length.

Which comb-like structures inside an American paddlefish's mouth strain food from the water as the fish swims forward?

Gill rakers work as a sieve of long, fine filaments. The extinct Chinese paddlefish had fewer, thicker ones and hunted fish instead.

In which country did scientists accidentally cross the American paddlefish with another ancient fish in 2019?

Hungary is where a routine control test put paddlefish sperm with another species' eggs. To the team's surprise, hundreds of hybrids hatched, and about 100 lived a full year.

In the 1970s, five thousand American paddlefish larvae were sent abroad to start fish farms in which country?

The Soviet Union received them through a science exchange between the two rivals' wildlife agencies. Descendants of those larvae have since been farmed from Germany to Bulgaria.

A 1980s US trade embargo on which country cut off its prized fish eggs and turned buyers toward paddlefish roe?

Iran's beluga from the Caspian Sea was the most prized and expensive of all. With imports restricted and Caspian stocks overfished, dealers and poachers turned to American rivers.

Which sense do American paddlefish barely use, relying instead on their sensitive paddles to find prey?

Vision matters so little that the fish hardly react to shadows passing overhead or to changes in light. Their eyes are small and poorly developed.

American paddlefish swim upstream in spring to shed their eggs over which river feature, flooded only at high water?

Gravel bars free of silt give the sticky eggs something clean to cling to. In a dry spring with no flood to cover them, the fish simply skip breeding.

Besides warming water and a rising river, which third cue must American paddlefish sense before they will spawn?

Longer days in spring switch on the breeding urge, but all three cues must line up. In the wild they once coincided only about one year in every four or five.

The largest American paddlefish on record, more than seven feet long, was speared in 1916 in a lake in which state?

Iowa's Okoboji Lake gave up the giant, which had a girth of nearly four feet and reportedly weighed over 198 pounds.

Which state began restocking American paddlefish in 1991, after they had died out in its Ohio and Allegheny rivers?

Pennsylvania released hatchery-reared fish hoping for a self-sustaining population. Adults were later netted there, a first step back for a species lost from the state.

Paddlefish are among the few animals to keep which flexible rod, normally lost before birth, as a lifelong spine?

Notochord is the term for the rod, which in paddlefish never gives way to a bony backbone. Their bodies contain very few bones of any kind.

Crossopholis, a fish-eating paddlefish that lived 52 million years ago, is known from which North American rock beds?

Green River Formation beds preserve it alongside the small schooling fish it ate. It is so rare there, under 0.02% of finds, that it probably spent most of its life in nearby rivers.

International trade in American paddlefish and their roe has been restricted since 1992 under which wildlife treaty?

The CITES convention lists the species in Appendix II, so cross-border trade in the fish, its parts and its eggs is regulated. Roe traffickers in America have been fined and jailed.

Which status did the IUCN Red List give the American paddlefish in 2004 and confirm again in 2022?

Vulnerable was the verdict both times, with overfishing and lost habitat the main causes. The 2022 review warned numbers could fall by at least 30% within three generations.

Some Chinese common names for the Chinese paddlefish compared its long snout to which animal feature?

An elephant's trunk was the comparison, apt for a fish whose snout made up as much as a third of its length. Fishermen in Sichuan also had a saying about its great size.

A ninth-century Tang dynasty book claimed that killing a Chinese paddlefish could bring on which kind of weather?

Rain was said to follow, a belief recorded in Miscellaneous Morsels from Youyang. An older text claimed the fish was drawn to the sound of musical instruments.

American paddlefish exported from China are farmed for their roe in which Caribbean country?

Cuba raises them for roe, a long way from their home rivers. China itself began with eggs sent from American hatcheries in 1988 and has imported millions a year since.

Which temporary feature do male American paddlefish grow on their heads and backs during the spring spawning season?

Sandpapery bumps, known as breeding tubercles, appear on the males each spring. The same spring run is when Oklahoma anglers go after the species.

How do young American paddlefish fingerlings feed during their first summer, before they become filter feeders?

Picking prey one by one, a fingerling must spot and intercept each tiny animal. The effort pays off: fry can grow about an inch a week in their first months.

Unlike the river-bound American species, young Chinese paddlefish spent part of their lives in which habitat?

Coastal seawater was their nursery: hatchlings drifted some 1,700 miles downriver to the estuary near Shanghai, then headed back upriver as they neared adulthood.

The 144-pound paddlefish that held the rod-and-reel world record from 2004 to 2020 was caught in which unlikely water?

A five-acre pond in Atchison County, Kansas, produced the giant for angler Clinton Boldridge. Two bigger fish from a single Oklahoma lake then beat it within a month of each other.

American paddlefish, far from home, were caught by fishermen in 2006 in the Serbian stretch of which river?

Danube fishermen near Prahovo netted several of different sizes. The species had been stocked in European rivers and fish farms since the 1970s.