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This short article from the quarterly Lifewatch magazine published by London Zoo describes the ancient species of American paddlefish.
Around 300 million years ago, long before dinosaurs roamed the earth, paddlefish inhabited the rivers of North America; fossil records from over 130 million years ago show these primitive fish have changed little since prehistoric times. Like their equally primitive relatives, the sturgeons, paddlefish have no scales or bony plates, and a cartilaginous skeleton like the sharks and rays. Another feature they share in common with sturgeon is their place among the largest and longest lived of freshwater fishes. The Chinese paddlefish—there are two species of paddlefish—is even larger than the American species. It is found only in the Yangtze river and can reach 10 feet (3 metres) in length and 175 lbs in weight. However, virtually nothing more is known of its biology.
Rivers in the Mississippi Valley, USA.
Paddlefish are filter feeders, that is, they sieve their food out of the water using gill rakers. When feeding, the lower jaw descends like a vast sack and gapes open as the fish swims, scooping up shoals of crustacea, aquatic insect larvae and other tiny plankton.
- No-one is certain of the purpose of the long paddle-like snout although the following suggestions have been offered:
- a) a stabiliser to balance the head against downward pressure in the huge mouth when feeding; b) an electrical sensory device for detecting swarms of plankton; c) a mud-digger; d) a tool for beating aquatic plants in order to release small organisms.…
- Paddlefish are nocturnal animals resting in the silt at the bottom of deep pools during the day.
- Spawning was only first observed in 1961. As the temperature of the water reaches 10°C, adults are stimulated to move upstream into the shallows.
- Paddlefish are extremely slow growing—it takes 8-12 years to reach maturity.…
None. However, humans threaten the survival of the species by destroying its habitat
All the paddlefish at London Zoo were bred in captivity. As part of the Zoo’s plans to refurbish the Aquarium, these extraordinary fish will be displayed in a circular tank at the entrance to the building which will have as its theme, the evolution and diversity of fish. A round tank is more suitable than one with straight sides as it helps prevent the paddlefish damaging their snouts on the glass.
Paddlefish are most often found in sluggish waters, silted pools, backwaters and the oxbows of large rivers.
Paddlefish were abundant in the Mississippi and its larger tributaries until about 1915. At that time, the construction of dams caused a dramatic loss in numbers by preventing the fish from migrating upstream to their spawning grounds. Subsequent pollution also threatened their survival. Today, improved water quality and a restocking programme involving captive-bred animals and the use of reservoirs for holding stock, are saving these fish from extinction.
Vulnerable.
- Weight—male 90 lbs
- Length—snout to tail up to 7’ (2m)
- Lifespan: up to 30 years
Source: Robinson, Claire. “Animal Focus”. Lifewatch magazine. Zoological Society of London [http://www.weboflife.co.uk]. Spring 1996.
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Paddlefish; Mississippi (river)
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