Grass pickerel (Esox americanus vermiculatus) COSEWIC assessment and status report: chapter 2

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Executive summary

Grass Pickerel
Esox Americanus Vermiculatus

Species information

Grass pickerel Esox americanus vermiculatus is a subspecies of Esox americanus redfin pickerel, family Esocidae. A small form, it is usually less than 30 cm in length, otherwise with features typical of the family: subcylindrical body, dorsal and anal fins far back on the body, snout protracted and well-armed with teeth.


Distribution

In Canada, it is limited to extreme southwestern Quebec and southern Ontario. In the United States, it is found in various states west of the Appalachian Mountains from western New York southwest to eastern Texas. 


Habitat

The grass pickerel is characteristic of warm, slow moving streams, isolated pools of such streams, and shallow bays of lakes. It is always associated with extensive submergent and emergent aquatic vegetation characteristic of the fishes in the family.


Biology

Principal spawning time in Canada is spring, shortly after ice has disappeared. Development and growth are fairly rapid. Life expectancy in Canada may be as long as 7 years, but shorter in southern populations. Food of newly hatched individuals is various macroscopic invertebrates, changing gradually to fishes, crayfishes, and the immature stages of aquatic insects, especially dragonflies.


Population sizes and trends

Population numbers fluctuate depending on water conditions. At times, an estimated 100 individuals have been reported in the isolated pools of typical streams. This species appears to leave those parts of streams in which they have been recorded if the condition deteriorates as a result of development, road and bridge building, or increased acidification.


Limiting factors and threats

All conditions resulting in low water levels, loss of aquatic vegetation, decreased water transparency, and lowering of stream temperatures are threats to the grass pickerel.


Special significance of the species

This fish is often the top predator in the communities of which it is characteristic. Early stages of the highly prized muskellunge may be vulnerable to grass pickerel predation.


Existing protection or other status designations

There are no direct protective measures directed at this species, but an extensive number of statutes and acts of the governments of the areas in which it lives provide indirect protection. The conservation status of Esox americanus (of both the subspecies, redfin and grass pickerel) is generally secure throughout its range.

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