Scientific Name: Coregonus sp.
Taxonomy Group: Fishes
Last COSEWIC Assessment: April 1987
Last COSEWIC Designation: Special Concern
SARA Status: Schedule 3, Special Concern - (SARA Schedule 1 provisions do not apply)
Image of Squanga Whitefish
Squanga Whitefish are morphologically extremely similar to Lake Whitefish, but populations of Squanga Whitefish are genetically distinct from sympatric Lake Whitefish in morphology and in proteins. Morphological differences include greater gill raker length, distance between gill rakers, size of the head, and length of the fins relative to the size of the body.
Distribution and Population
The Squanga Whitefish is restricted to Canada. It is known at present from only four lakes in the Yukon Territory: Dezadeash Lake in southwestern Yukon, and Squanga, Little Teslin and Teenah lakes in south-central Yukon. The species also existed in Hanson Lake in central Yukon, but was poisoned along with all other fish species to prepare this lake for Rainbow Trout planting. A fifth extant population may occur in Tatchun Lake in central Yukon. Actual population estimates and trends are not known, but catch per unit effort values over a two year period indicate that the fish is relatively abundant in all four southern Yukon lakes.
The most striking common ecological feature of the four southern Yukon lakes where the fish is known, is the absence of the Least Cisco (Coregonus sardinella). Ciscoes have an otherwise wide distribution in the Yukon, and the Squanga Whitefish apparently is outcompeted from lakes where they occur. With the exception of Hanson Lake, all lakes which support or supported Squanga Whitefish have extensive littoral (shallow) areas. These lakes also have a low abundance of fish species which prey on other fish.
The Squanga Whitefish is an early maturing fish with a relatively short life span. Sexual maturity is attained at 2 to 5 years; spawning is probably annual. The Squanga probably behaves like other whitefish, broadcast spawning with fertilization occurring in the water column, eggs settling to the bottom, and the eggs and fry receiving no parental care. Preferred substrates for these fish are sandy or rocky bottoms. Squanga Whitefish feed mainly on pelagic and surface food items such as zooplankton and chironomid pupae.
The Squanga Whitefish is susceptible to all forms of habitat degradation, such as thermal pollution, severe water level fluctuations, high levels of suspended sediments, and other disturbances which impact on the availability of prey. The fish is apparently unable to coexist with ciscoes, which may be more effective consumers of zooplankton; therefore introduction of ciscoes to a Squanga Whitefish lake would result in the elimination of the whitefish. Similarly, a whitefish population could be significantly reduced by the addition of a piscivorous (fish-eating) fish to its lake. The only documented decline of a Squanga Whitefish population occurred when the Hanson Lakes were poisoned to prepare them for the planting of Rainbow Trout.
Species that were designated at risk by COSEWIC prior to October 1999 must be reassessed against revised criteria before they can be considered for addition to Schedule 1 of the Species at Risk Act (SARA). To find out when re-assessment of this species is anticipated, please consult the COSEWIC web site.
The Federal Fisheries Act prohibits destruction of fish habitat. The presence of the fish was recognized and considered in the proceedings of the Alaska Highway Pipeline Environmental Assessment Panel, which resulted in a routing relocation to protect it.
Provincial and Territorial Protection
PLEASE NOTE: Not all COSEWIC reports are currently available on the SARA Public Registry. Most of the reports not yet available are status reports for species assessed by COSEWIC prior to May 2002. Other COSEWIC reports not yet available may include those species assessed as Extinct, Data Deficient or Not at Risk. In the meantime, they are available on request from the COSEWIC Secretariat.
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