American Paddlefish
Encyclopedia
The American paddlefish, Polyodon spathula, also called the Mississippi paddlefish or spoonbill, is a paddlefish
living in slow-flowing waters of the Mississippi River
drainage system. It appears to have been extirpated from Lake Erie
and its tributaries. They are closely related to the sturgeon
s. This large Chondrostean freshwater fish may grow to 220 cm (7 feet) and weigh up to 100 kg (220 pounds). The paddlefish takes its common and scientific names from its distinctive snout, which is greatly elongated and flattened into a paddle shape. The American paddlefish is believed to use sensitive electroreceptors on its paddle to detect prey, as well as to navigate while migrating to spawning sites. The American paddlefish feeds primarily on zooplankton
but also feeds on crustaceans and bivalve
s. Polyodon spathula is one of two living species of Paddlefish
; the other is the possibly extinct Chinese Paddlefish
, Psephurus gladius.
Though the American paddlefish was once common throughout the Midwest, overfishing and habitat changes have caused major population declines; both the meat and roe
of Polyodon spathula are desirable as food. Dams and other barriers can prevent the fish from recolonizing places where they once occurred and can deny them access to important critical habitat
s such as spawning areas. Until about 1900, the species was also found in Lake Erie
and in river systems tributary thereto in the U.S. and Canada
. Invasive species such as zebra mussel
s have reduced the number of zooplankton
in the Great Lakes to such low levels that any hypothetical reintroduction program would seem likely to fail. Recently, paddlefish were spotted in the Danube
river. It has not been determined whether these fished escaped from Romania
n or Bulgaria
n fish farms
during the 2006 European floods
, or whether they were let into the Danube earlier and matured in the river.
and must be caught by snagging. Several states, including Missouri
, have enacted stocking programs for these fish in reservoirs where the resident populations were low or nonexistent, or in areas where historical populations are no longer naturally sustainable. Paddlefish roe is occasionally sold as "American Sevruga Caviar"http://www.affordablecaviar.com/paddlefishcaviar.
Paddlefish
Paddlefish are primitive Chondrostean ray-finned fishes. The paddlefish can be distinguished by its large mouth and its elongated, spatula-like snout, called a rostrum, which is longer than the rest of the head...
living in slow-flowing waters of the Mississippi River
Mississippi River
The Mississippi River is the largest river system in North America. Flowing entirely in the United States, this river rises in western Minnesota and meanders slowly southwards for to the Mississippi River Delta at the Gulf of Mexico. With its many tributaries, the Mississippi's watershed drains...
drainage system. It appears to have been extirpated from Lake Erie
Lake Erie
Lake Erie is the fourth largest lake of the five Great Lakes in North America, and the tenth largest globally. It is the southernmost, shallowest, and smallest by volume of the Great Lakes and therefore also has the shortest average water residence time. It is bounded on the north by the...
and its tributaries. They are closely related to the sturgeon
Sturgeon
Sturgeon is the common name used for some 26 species of fish in the family Acipenseridae, including the genera Acipenser, Huso, Scaphirhynchus and Pseudoscaphirhynchus. The term includes over 20 species commonly referred to as sturgeon and several closely related species that have distinct common...
s. This large Chondrostean freshwater fish may grow to 220 cm (7 feet) and weigh up to 100 kg (220 pounds). The paddlefish takes its common and scientific names from its distinctive snout, which is greatly elongated and flattened into a paddle shape. The American paddlefish is believed to use sensitive electroreceptors on its paddle to detect prey, as well as to navigate while migrating to spawning sites. The American paddlefish feeds primarily on zooplankton
Zooplankton
Zooplankton are heterotrophic plankton. Plankton are organisms drifting in oceans, seas, and bodies of fresh water. The word "zooplankton" is derived from the Greek zoon , meaning "animal", and , meaning "wanderer" or "drifter"...
but also feeds on crustaceans and bivalve
Bivalvia
Bivalvia is a taxonomic class of marine and freshwater molluscs. This class includes clams, oysters, mussels, scallops, and many other families of molluscs that have two hinged shells...
s. Polyodon spathula is one of two living species of Paddlefish
Paddlefish
Paddlefish are primitive Chondrostean ray-finned fishes. The paddlefish can be distinguished by its large mouth and its elongated, spatula-like snout, called a rostrum, which is longer than the rest of the head...
; the other is the possibly extinct Chinese Paddlefish
Chinese Paddlefish
Chinese Paddlefish, Psephurus gladius , also known as Chinese Swordfish, are among the largest freshwater fish. It is one of two extant paddlefish species, the other being the American Paddlefish . It is also called "elephant fish" because its snout resembles an elephant trunk...
, Psephurus gladius.
Population decline
Roe
Roe or hard roe is the fully ripe internal egg masses in the ovaries, or the released external egg masses of fish and certain marine animals, such as shrimp, scallop and sea urchins...
of Polyodon spathula are desirable as food. Dams and other barriers can prevent the fish from recolonizing places where they once occurred and can deny them access to important critical habitat
Habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...
s such as spawning areas. Until about 1900, the species was also found in Lake Erie
Lake Erie
Lake Erie is the fourth largest lake of the five Great Lakes in North America, and the tenth largest globally. It is the southernmost, shallowest, and smallest by volume of the Great Lakes and therefore also has the shortest average water residence time. It is bounded on the north by the...
and in river systems tributary thereto in the U.S. and Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
. Invasive species such as zebra mussel
Zebra mussel
The zebra mussel, Dreissena polymorpha, is a small freshwater mussel. This species was originally native to the lakes of southeast Russia being first described in 1769 by a German zoologist Peter Simon Pallas in the Ural, Volga and Dnieper rivers. They are still found nearby, as Pontic and Caspian...
s have reduced the number of zooplankton
Zooplankton
Zooplankton are heterotrophic plankton. Plankton are organisms drifting in oceans, seas, and bodies of fresh water. The word "zooplankton" is derived from the Greek zoon , meaning "animal", and , meaning "wanderer" or "drifter"...
in the Great Lakes to such low levels that any hypothetical reintroduction program would seem likely to fail. Recently, paddlefish were spotted in the Danube
Danube
The Danube is a river in the Central Europe and the Europe's second longest river after the Volga. It is classified as an international waterway....
river. It has not been determined whether these fished escaped from Romania
Romania
Romania is a country located at the crossroads of Central and Southeastern Europe, on the Lower Danube, within and outside the Carpathian arch, bordering on the Black Sea...
n or Bulgaria
Bulgaria
Bulgaria , officially the Republic of Bulgaria , is a parliamentary democracy within a unitary constitutional republic in Southeast Europe. The country borders Romania to the north, Serbia and Macedonia to the west, Greece and Turkey to the south, as well as the Black Sea to the east...
n fish farms
Fish farming
Fish farming is the principal form of aquaculture, while other methods may fall under mariculture. Fish farming involves raising fish commercially in tanks or enclosures, usually for food. A facility that releases young fish into the wild for recreational fishing or to supplement a species'...
during the 2006 European floods
2006 European floods
From February to April 2006 many rivers across Europe, especially the Elbe and Danube, swelled due to heavy rain and melting snow and rose to record levels...
, or whether they were let into the Danube earlier and matured in the river.
Sport fishing
The American paddlefish remains a popular sport fish in those parts of its range where populations are sufficient to allow harvesting. Since they are filter-feeders, paddlefish will not accept bait or luresFishing lure
A fishing lure is an object attached to the end of a fishing line which is designed to resemble and move like the prey of a fish. The purpose of the lure is to use movement, vibration, and colour to catch the fish's attention so it bites the hook...
and must be caught by snagging. Several states, including Missouri
Missouri
Missouri is a US state located in the Midwestern United States, bordered by Iowa, Illinois, Kentucky, Tennessee, Arkansas, Oklahoma, Kansas and Nebraska. With a 2010 population of 5,988,927, Missouri is the 18th most populous state in the nation and the fifth most populous in the Midwest. It...
, have enacted stocking programs for these fish in reservoirs where the resident populations were low or nonexistent, or in areas where historical populations are no longer naturally sustainable. Paddlefish roe is occasionally sold as "American Sevruga Caviar"http://www.affordablecaviar.com/paddlefishcaviar.