Grass Pickerel

Description
Habitat
Threats
Scientific Information
Further Information

Description

Esox americanus vermiculatus

© J.R. Tomelleri

The Grass Pickerel (Esox americanus vermiculatus) is a subspecies of the Redfin Pickerel and a small member of the Pike family (Esocidae). In addition to the distinguishing family features (large mouth; many teeth; forked tail; and posterior dorsal and anal fins), the Grass Pickerel has the following characteristics:

• Long, relatively shallow body that is cylindrical in shape;
• Colouration is variable but usually green to brown with 12 to 24 irregular, vertical, narrow, dark bars, and a mid-dorsal brown stripe;
• Juveniles have a prominent pale lateral band that disappears with maturation;
• Dusty yellow-green lower fins;
• Protracted snout, concave in profile;
• Fully scaled cheeks and opercula (hard bony flap protecting the gills); and
• Usually less than 300 mm in total length; maximum total length and weight are 381 mm and 500 g respectively.

Habitat
Predominantly located in the U.S., the Grass Pickerel is largely restricted to the west of the Appalachian Mountains, in the Great Lakes and the Mississippi River basin. In Canada, its range is disjunct and is represented by several populations in southwestern Quebec and southern Ontario. It has been found in the St. Lawrence River, as well as in shallow bays and tributaries of eastern and southwestern Lake Ontario, inland watercourses of the Niagara region, and along the north shore of Lake Erie. Populations occur in Lake St. Clair and some of its tributaries. It is also found in several tributaries and waterbodies in the lower Lake Huron watershed. There have been no confirmed reports of the species in Quebec for the past 20 years. According to some historical observations, the Grass Pickerel was found in three separate areas separated by natural and man-made obstacles ((i.e. rapids, dams and weirs): in Lake Saint François; 2) in the main channel of the St. Lawrence River near Coteau-du-Lac; and 3) in Lake St. Louis and its tributaries.

The habitat of the Grass Pickerel is characterized by warm, slow-moving streams, ponds and shallow bays of larger lakes, with clear to tea-coloured water, and abundant aquatic vegetation. Bottom substrate is usually mud, but it has also been found over rock and gravel. Adults reach sexual maturity by two years of age. Associated with overland flooding, spawning occurs in the spring in water temperatures of 4° to 12°C; however, there is evidence of late summer to winter spawning as well. Eggs are dispersed and adhere to aquatic vegetation. No nest is built and neither eggs nor young are provided parental care. Adult lifespan is seven years or less.

Threats
Grass Pickerel in Canada is at the northern extent of its range. Principal threats to its future survival in Canada are habitat destruction and degradation. Grass Pickerel appear to have specific habitat requirements, and their long-term viability may be threatened by continued development and human encroachment at some locations. Of particular concern has been the loss of wetland habitat through rural land use practices, including agricultural and other development activities. Additional potential threats identified for populations in Ontario and Quebec include drainage, damage/destruction of riparian or aquatic vegetation, sediment and nutrient loading, contaminants input, exotic species, interspecific interactions, climate change, fishing pressure, water level fluctuations (beyond natural seasonal variability), disease and barriers to movement.

Further Information:
A management plan for the Grass Pickerel was published in 2012. It provides a summary of current knowledge, identifies threats to the species and its habitat and recommends measures to maintain and improve Grass Pickerel populations.

The Grass Pickerel hasn’t been recorded in Quebec in over 20 years. If you accidentally capture a Grass Pickerel in Quebec, it is very important to advise the Centre de données sur le patrimoine naturel du Québec of your catch, and to release the fish back into the water in a manner that maximizes its chances of survival. 

Scientific Information:

Scientific Name:  Esox americanus vermiculatus
SARA Status: Special Concern (September 2006)
COSEWIC Status: Special Concern (May 2005)