Cultus Pygmy Sculpin
Drawing of coastrange sculpin, Cottus aleuticus, a close relative of Cultus pygmy sculpin.
Illustration by Susan Laurie Bourque, reproduced courtesy of the Canadian Museum of Nature, Ottawa, Canada.
Species at Risk Act
SARA Status: Threatened
Common Names: Cultus pygmy sculpin
Scientific Name: Cottus sp.
COSEWIC Assessment Summary: May 2000
COSEWIC Status: Threatened
COSEWIC Reason for Designation: Endemic to British Columbia, this species is restricted to one small lake, which is in an area subject to industrial and urban development. The species is also preyed on by salmonids co-existing in the lake.
Canadian Occurrence: British Columbia
COSEWIC Status History: Designated Special Concern in April 1997. Status re-examined and designated Threatened in November 2000. Last assessment based on an existing status report.
Brief Description of Cultus Pygmy Sculpin and Its Habitat
The Cultus pygmy sculpin was first identified in 1934 and most of what we know about it comes from a single paper, published by Ricker in 1960. Ricker described this taxon as a dwarf form of the coastrange sculpin, Cottus aleuticus, which has pelagic larvae but adopts a benthic habit after about 32 to 35 days. The Cultus pygmy sculpin shares many physical features of the coastrange sculpin and of sculpins in general, but there are also important differences in morphology and ecology, most importantly small body size, retention of larval features, and a limnetic existence. The Cultus pygmy sculpin retains larval features (suggesting neotenic evolution), and has a number of adaptive traits characteristic of a limnetic existence, rather than the benthic habits typical of sculpins. These features include reduced bone density, enlarged head pores and an increase in subcutaneous lipids. Observed diets of plankton corroborate the findings of limnetic habits.
Cultus pygmy sculpin appear to spend the majority of time in the limnetic zone of the lake where they forage on plankton. The species likely depends on productive plankton resources, but precise habitat requirements are not known. It is assumed that the species uses deep littoral areas for spawning and incubation, but natural spawning has not been observed.
The Cultus pygmy sculpin is an extreme endemic. It is found only in Cultus Lake, British Columbia, which drains via Sweltzer Creek into Vedder River, a tributary of the Lower Fraser River mainstem approximately 112 km upstream of its confluence with the Strait of Georgia. No other populations have been documented in BC although a similar form has been observed in Lake Washington, WA, and is believed to have evolved independently. There has been no systematic search for additional populations similar to those in Cultus and Washington lakes. However, fisheries surveys of lakes have occurred frequently in the past and would likely have detected limnetic coastrange sculpins if they were moderately widespread beyond these locations.
Cannings, S.G. and J. Ptolemy. 1998. Rare freshwater fish of British Columbia. Unpublished report to Ministry of Environment, Lands and Parks, Victoria, BC.
COSEWIC 2003. COSEWIC assessment and status report on the sockeye salmon Oncorhynchus nerka (Cultus Population) in Canada. Committee on the Status of Endangered Species Wildlife in Canada, Ottawa. Ix + 57 pp.
Heard, W.R. 1965. Limnetic cottid larvae and their utilization as food by juvenile sockeye salmon. Transactions of the American Fisheries Society 94: 191-193.
Larson, K.W. and G.W. Brown Jr. 1975. Systematic status of a midwater population of freshwater Sculpin (Cottus) from lake Washington, Seattle, Washington. Journal of the Fisheries Research Board of Canada 32: 21-28.
McLarney, W.O. 1968. Spawning habits and morphological variation in the coastrange sculpin, Cottus aleuticus, and the prickly sculpin, Cottus asper. Transactions of the American Fisheries Society 97: 46-48.
McPhail, J.D., and R. Carveth. 1990. A foundation for conservation : the nature and origin of the freshwater fish fauna of British Columbia. Unpublished report to Fisheries Branch, B.C. Ministry of the Environment, Lands and Parks, Victoria, B.C.
Ricker, W.E. 1960. A population of dwarf Coastrange Sculpins (Cottus aleuticus). Journal of the Fisheries Research Board of Canada 17:929-932.
Schubert, N.D. et al. 2002. Status of Cultus Lake sockeye salmon (Oncorhynchus nerka). PSARC Working Paper.
Taylor, J. 2006. Draft status report on Cultus Pygmy Sculpin [Cottus sp.]. unpublished manuscript.
Recovery Team Documents