Nature Canada

Species Spotlight: Greensided Darter

Get to know some of the species at risk in the Lac Deschenes Ottawa River IBA with the Species Spotlight, aka “Sp-Spot.” Today meet the: Greenside Darter

Scientific Name: Etheostoma blennioides
SARA Status: Special Concern
Taxonomic group: Fishes
Size: 76 mm length, but can reach up to 140 mm

Greenside Darter

Greenside Darter

The Greenside darter has a cylindrical body, the head is wide and triangular, and the snout is rounded and is slightly extended to the mouth. It has two dorsal fins that are very close together, the caudal fin (tail) is slightly forked and pectoral fins (those along the sides) are slightly pointed, large and well-developed. Juveniles have more pointed pelvic fins than adults.  Males are larger and more colorful than females. This fish is olive-green with green V-shaped marks on the sides.

Greenside darters reach sexual maturity after 1 year of hatching and can live up to 3-4 years. Spawning occurs in spring and early summer, and eggs are deposited under rocks cover with filamentous green algae. Spawning occurs in pairs, and both sexes will spawn with different partners during the breeding season. There is no parental care, but males usually guard the territory where eggs were laid, although with time this becomes more difficult because males continue to mate with multiple females over the season.

Because Greenside darters have no swim bladder, an organ which allows many fish to control their buoyancy and thus stay at a particular depth easily in currents, they live at the bottom of rivers, streams and lakes. Species that live at the bottom of a water body are considered benthic. They like to eat immature benthic insects like midge, mayfly and blackfly larvae.

Greenside Darter also prefers to live in clear and moderate to fast flow waters.

Runoffs from farmlands and urban development to rivers and creeks are threats to Greenside darter populations affecting them directly or through their food supply. Habitat loss has been an important factor for this species decline in several places.

Where Else Can You See This Species?
Greenside darters can be found in few river systems in southwestern Ontario, it has been reported on Thames River, Ausable, Sydenham and Big Creek drainages. This species was introduced to the Grand River in early 90’s, but has disappeared in several other locations in the province.

Did you know?
•    Darters communicate mainly through coloration; males use it to intimidate other males or to attract females. And females may change color contrast to communicate with males.
•    They show a defensive behavior known as Freezing and can stop moving for some time when a predator is close by.
•    The Greenside darter plays an important role as a host in the reproductive cycle of several freshwater mussels in their larval stage, providing them with transportation and distribution into other areas.
•    Breeding only occurs when the water temperature is between 11 to 23 degrees.
•    Their predators are smallmouth bass and several kinds of trout.

Check back every week to read about a different species at risk that can be found in Lac Deschênes.
You can report sightings of this and other rare species to the Canadian Wildlife Service at (819) 997-2800 or on the MNR Natural Heritage Information Centre website. A photo and the location of your sighting are also very helpful!

We would like to thank our guest blogger Monica Reyes for this post. Monica is a conservation volunteer for Nature Canada.She is a biologist from Mexico interested in wildlife conservation and environmental education.

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