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Consultation on adding two species to SARA : “Eastslope” sculpin & Grass pickerel

Part 2:  Information about the species
“Eastslope” sculpin (St. Mary and Milk river populations)

Status:  Threatened

Last Examination by COSEWIC:  May 2005

Biology

The “Eastslope” sculpin (St. Mary and Milk river populations) is a small freshwater sculpin with a large head and heavy body that tapers from head to tail are characteristics of this family of fish.

Diet consists mainly of aquatic insect larvae but mollusks, fish and sculpin eggs are also ingested.

Life history information for this sculpin is extremely limited and most of it is based on one study of Cottus species (that includes the “Eastslope” sculpin (St. Mary and Milk river populations)) in Alberta. Spawning occurs in late spring when the water temperature is between 7.5ºC and 15ºC. Fecundity generally ranges from 100-250 eggs. Eggs hatch within 2 to 3 weeks depending on the temperature. Young of the year measure 30-40 mm in total length by the end of their first summer and yearlings achieve a length of at least 50 mm. Both sexes are sexually mature by 23 months of age. Maximum fork length is 114 mm.

Where is this fish found?

The “Eastslope” sculpin (St. Mary and Milk river populations) is found in the St. Mary and Milk rivers in Alberta and Montana. In Alberta, it has an extremely limited distribution, being present in the St. Mary River above the St. Mary reservoir, the North Milk River and main stem of the Milk River.

It prefers cooler water temperatures and clean rocky substrates. Fish are found predominately in shallow runs and riffles, as well as run/boulder gardens.

How many fish are there?

No studies have been conducted to estimate the population size of this sculpin in Alberta. However, surveys were conducted in 2000 and 2001 to measure its relative abundance. Highest abundance values were observed in the North Milk River. Abundance decreased downstream to where they were absent in the lowest section of the Milk River mainstem. In contrast, they were evenly distributed throughout the St. Mary River.

Threats to the population

Water removal, diversions and reservoirs associated with irrigation, in combination with the frequent droughts of southern Alberta, have likely had the greatest impact on population size and distribution over time and will continue to be the greatest threats to its existence.

COSEWIC Reason for Designation:

This species has a very restricted area of occurrence in the St. Mary and Milk rivers in Canada, where it has been impacted by habitat loss and degradation from water diversion, conditions that have been exacerbated in recent years by drought.

What will happen if this population is added to the SARA List?

  • If listed, general prohibitions under SARA would come into effect making it unlawful to kill, harm, harass, capture or take the species  
  • Under SARA, a recovery strategy must be developed within two years of listing for the “Eastslope” sculpin (St. Mary and Milk river populations). Preliminary work on a recovery strategy has already been initiated by Fisheries & Oceans Canada in co-operation with Alberta Sustainable Resource Development in connection with the Milk River Fish Species Recovery Team.  This initial work will be expanded to include the St. Mary River populations upon listing

Grass pickerel

Status:  Special Concern

Last Examination by COSEWIC:  May 2005

Biology

The grass pickerel resembles a small northern pike; it, however, can be distinguished from northern pike and muskellunge by its small adult size (less than 30 cm in length), more cylindrical body shape and the presence of three dark bars below the eyes. The body of the grass pickerel is green to brownish in colour with 12 to 24 irregular, more or less vertical, narrow, dark bars and a mid-dorsal brownish stripe and fins that lack strong colour or markings.

Diet of newly hatched individuals consists of various large aquatic insects, changing gradually to include fishes and crayfishes as the grass pickerel matures.

Spawning occurs mainly in spring in, or at the edge of aquatic vegetation. Eggs are slightly adhesive and adhere to vegetation that is at or near the bottom of the water. In Ontario, spawning takes place in water temperatures approximately 8-12ºC, eggs hatch in 11-15 days at temperatures of 7.8-8.9ºC and the time period between spawning and the start of feeding by young is 2-5 weeks depending on water temperature. In Ontario adults reach sexual maturity at two years of age. Maximum recorded size in Canada is 328 mm total length and 204 g.

Where is this fish found?

In Canada, the grass pickerel is limited to extreme southwestern Québec and southern Ontario. In Québec, it is known from three sections of the St. Lawrence River. In Ontario, it is present in the St. Lawrence River and its tributaries; Lake Ontario and its tributaries (including Upper Niagara and Welland rivers); north shore of Lake Erie; the upper portion of, and drainage tributaries to, Lake St. Clair; Lake Huron watershed.

The grass pickerel prefers warm, slow moving streams, and shallow bays of lakes. It is always associated with extensive submergent and floating aquatic vegetation.

How many fish are there?

Population numbers fluctuate depending on water conditions. An estimate of 100 individuals has been reported in isolated pools of typical streams.

Threats to the population

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.

COSEWIC Reason for Designation:

It is a subspecies known from 10 locations between Lake St. Louis, Quebec and Lake Huron, Ontario. Its usual habitat is shallow water with abundance of aquatic vegetation. An overall decline of approximately 22% in the area of occupancy has been observed. This decline appears to be related to degradation and loss of habitat due to channelization and dredging operations in wetland habitats where this species occurs.

What will happen if this population is added to the SARA List?

  • Under SARA, a management plan must be developed within three years of the grass pickerel being listed
  • The grass pickerel is included in the Essex-Erie Fishes Recovery Strategy which is in development