Northern Sunfish
Lepomis peltastes
Species Description
A small, striking and vibrantly coloured member of the family Centrarchidae (Sunfish and Bass), the Northern Sunfish adds a dash of tropical colour to Ontario waters. This fish can grow to be about 13cm long and has a deep, laterally compressed body with energetic blue markings, a brilliantly bright orange belly, and an olive green back. The operculum, referred to commonly as the “ear flap”, is elongated and upturned supporting a narrow white or red edge that helps distinguish this species from other sunfish.
They are most often found in clear, warm, shallow waters of rivers, lakes, and ponds with abundant aquatic vegetation and low flow. The preference for clear waters and brilliant colouration of males indicates that visual communication is important during spawning.
The territorial males create circular nests in shallow, gravelly areas, often in colonies. The males will also produce grunting sounds during courtship to attract females. Females deposit their eggs in these nests which are fertilized and guarded by the males until they hatch after 3-5 days.
Rather than invest energy in excavating nests, producing bright colour displays and courtship sounds to attract a female, some males of this species adopt an alternative reproductive tactic. Cryptically coloured “sneaker” males will dart into nesting sites and steal fertilizations from more dominant males.
Distribution in the Sydenham
The Northern Sunfish occurs in Ontario and Quebec in Canada and the northern United States. In southern Ontario, it is found in tributaries of Lake Huron, Georgian Bay, Lake St. Clair, Lake Erie, and Lake Ontario.
The first record of the Northern Sunfish in the Sydenham River is from 1936 and, as sampling has increased over time, has been recorded in the Sydenham relatively consistently since the 2000s. Due to the sampling protocols used, population abundance estimates are not available for this species but it is not considered common in Canada.
Threats to the Northern Sunfish
When visual displays play an important role in the life cycle of a fish, cloudy waters can significantly impact that species’ survival.
The largest threats to the Northern Sunfish are turbidity, siltation, and contaminants caused by runoff from agricultural and development activities. Additional threats include the removal of aquatic vegetation, invasive species like the Roundy Goby, collection for the ornamental fish trade, and fisheries bycatch.