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Exotic Species

 

A Few Newcomers in the Rideau River

Common carp, Cyprinus carpio.
Common carp, Cyprinus carpio.
Fish
Common carp
The common carp (Cyprinus carpio) is native to Europe and Asia, but it was introduced into Ontario from the United States in 1880. The species quickly spread throughout southern Ontario and has reached as far north as Sturgeon Bay, Ontario. The common carp has been found throughout the Rideau River since the 1930s.

This fish has been blamed for destroying the spawning areas of many aquatic insects, amphibians and fish. Common carp roots in the mud along shorelines, and in doing so it uproots aquatic plants. This activity also increases the turbidity. Other fish will avoid these areas as the suspended particles block their grills. If eggs have already been laid in these areas, the particles will cover them and interfere in their development. [3, 4, 5, 6]

Turtles
Red-eared slider
A red-eared slider (Trachemys scripta elegans) is easily recognized by its black shell with yellow stripes and the bright red patch just behind the eye. These turtles are native to the southern U.S. and are sold throughout North America as pets.


Red-eared slider, Trachemys scripta elegans.
Red-eared slider, Trachemys scripta elegans.

Red-eared sliders have expanded their distribution into the Rideau River because they have been dumped there by pet owners. This species successfully over-winters in the River, but is not likely to reproduce at this latitude since its natural range is in warmer waters further south.

The red-eared slider competes with native turtles for food and basking sites. It can also occupy areas that are favourable nesting sites for native turtles. [3, 4, 5, 6]

Crayfish
Rusty crayfish
The rusty crayfish (Orconectes rusticus) is native to Ohio, Kentucky and Tennessee (in the U.S.), but it has been spread by anglers into northern, non-native waters through careless emptying of bait buckets and livewells.

Rusty crayfish were first captured in 1986 in the Jock River, which is a tributary to the Rideau River. Two years later, this species of crayfish was found in the Rideau River itself.

The rusty crayfish is an aggressive predator that dramatically reduces diversity of both aquatic plants and invertebrate populations, and defeats native crayfish species in competition for food and cover. Rusty crayfish have drastically reduced native crayfish populations in many areas of Ontario. [3, 4, 5, 6]

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 Newcomers
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A Project of the Canadian Museum of Nature
 Images: Canadian Museum of Nature, Smithsonian Institution, NMNH, Division of Fishes