CDC Logo

BC Conservation Data Centre: Conservation Status Report

Dicamptodon tenebrosus
Coastal Giant Salamander


 
Scientific Name: Dicamptodon tenebrosus
English Name: Coastal Giant Salamander
English Name Synonyms: Pacific Giant Salamander
   
Provincial Status Summary
Status: S2
Date Status Assigned: June 01, 1996
Date Last Reviewed: December 15, 2010
Reasons: Restricted range and fragmented distribution; threatened by logging activities that reduce stream persistence. Populations appear to be stable. Overall threat to this species' habitat has likely lessened with the establishment of 20 Wildlife Habitat Areas (WHA) (2007-2008), however monitoring is necessary to determine the effectiveness of these WHAs.
 
Range
Range Extent: C = 250-1,000 square km
Range Extent Comments: Restricted to the Chilliwack River and nearby, smaller watersheds (Haycock 1991; Richardson and Neill 1995) between and immediately surrounding Cultus and Chilliwack lakes (Matsuda et al. 2006). 2010: Calculated to be 690 km2, using the Alpha Hull method.
Area of Occupancy: E = 26-125
Linear Distance of Occupancy: DE = 21-500
Area of Occupancy Comments: Ferguson and Johnstone (2000) state linear distance of occupancy as 80 km and area of occupancy as 80 square kilometres (assume salamanders occupy 0.5 km of either side of a creek). 2010: calculated to be 328 km2, or 82 4km2 grid cells using the Alpha Hull method.
 
Occurrences & Population
Number of Occurrences: C = 21 - 80
Comments: Known from 60 small streams in the Chilliwack River drainage; the number of occurrences will be fewer as there are streams within the 1 km suitable distance separation distance (Richardson and Neill 1994).
Number of Occurrences with Good Viability / Ecological Integrity: D = 13 - 40
Comments: Estimated based on the assumptions by Farr (1989), Haycock (1991) and Ferguson and Johnstone (2000) that decline, if any, is not apparent.
Number of Occurrences Appropriately Protected & Managed: D = 13 - 40
Comments: Chilliwack Lake Park protects several creeks. This species is listed as Identified Wildlife under the Forest and Range Practices Act. In 2007, 20 Wildlife Habitat Areas (WHA), approximately 770 ha, were established on crown land in the Chilliwack Forest District to protect this species. This protects approximately 63 linear kilometers of occupied habitat in WHAs and another 19 km within parks.
Population Size: F = 10,000 - 100,000 individuals
Comments: Ferguson and Johnstone (2000) provide a gross estimate of 13,400 terrestrial adults and an upward estimate of 9000 neotenic adults for a total estimate of 22,400 sexually mature salamanders. Larval densities in "high density" streams in the Chilliwack drainage ranged from 0.43 to 2.53 larvae per metre of stream (Richardson and Neill 1997).
 
Threats (to population, occurrences, or area affected)
Degree of Threat: Moderate and imminent threat
Comments: The scope of threat has been reduced from high to medium as 20 Wildlife Habitat Areas (WHA) were established in 2007. Logging practices can reduce stream persistence (Richardson and Neill 1997). The establishment of these WHAs should prevent stream damage from logging, however monitoring of these sites is needed to ensure that the WHAs are in fact providing adequate protection. Further, terrestrial adults are potentially threatened by clearcut logging. Road building and hydrological diversion threatens the integrity of streams (Haycock 1991). The severity of the threat is moderate since major loss of habitat and subsequent reductions in population size are possible. The immediacy of the threat is high and may be operational within 1 year for any individual stream. Recolonization of streams is very slow, and only one in every five streams in the Chilliwack drainage is occupied by this salamander (Richardson and Neill 1997) which increases the vulnerbility of this species. In 2008, 27 Pacific Giant Salamanders were tested for the presence of the fungus, Batrachochytrium dendrobatidis (Bd), which causes chytridiomycosis disease; no individuals tested positive (P. Govindarajulu, pers. comm. 2010).
 
Trend (in population, range, area occupied, and/or condition of occurrences)
Short-Term Trend: G = Relatively Stable (<=10% change)
Comments: Ferguson and Johnstone (2000) state decline as 2% which includes the historic losses of Sumas Lake and Vedder River. Note that decline is largely unstudied.
Long-Term Trend: U = Unknown
Comments: Ferguson and Johnstone (2000) state decline as 2% which includes the historic losses of Sumas Lake and Vedder River.
 
Other Factors
Intrinsic Vulnerability: A=Highly vulnerable
Comments: Ferguson (1998) and Johnstone (1998) show very low dispersal rates for larvae and terrestrial adults respectively. Recolonization is assumed to be very low.
Environmental Specificity: B=Narrow. Specialist or community with key requirements common.
Comments: The species has terrestrial and aquatic life forms requiring steeply inclined stream habitat.
Other Rank Considerations: Dispersal is very low and therefore recolonization is compromised, but recovered stream habitat is also very low.
 
Information Gaps
Research Needs: Further investigation into dispersal rates of larvae and terrestrial and aquatic adults may provide insights into the effectiveness of rescue efforts for the species. Rescue efforts may be required at unprotected streams that have been compromised by logging and where the size of the population said stream has been eliminated or significantly reduced. Continued research on the effects of timber harvest needed.
Inventory Needs: Detailed inventory undertaken by University of British Columbia researchers, 1994-96 (Richardson and Neill 1994). Continued monitoring needed to establish trends.
 
Stewardship
Protection: This species is listed as Identified Wildlife under the Forest and Range Practices Act.
Management: Ensure that logging practices do not damage stream integrity. Some entire, small watersheds should be protected.
 
Version
Author: R. Haycock, L. Ramsay and L. Westereng
Date: February 11, 2008
 
References
Daugherty, C.H., F.W. Allendorf, W.W. Dunlap and K.L. Knudsen. 1983. Systematic implications of geographic patterns of genetic variation in the genus Dicamptodon. Copeia 1983:679-691.
Farr, A.C.M. 1989. Status report on the Pacific giant salamander, Diacamptodon ensatus, in Canada., Unpubl. rep. submitted to the Comm. on the Status of Endangered Wildl. in Can., Ottawa, ON.
Ferguson, H.M. 1998. Demography, dispersal and colonisation of larvae of Pacific Giant Salamanders (Dicamptodon tenebrosus, Good) at the northern extent of their range. M.Sc. Thesis, University of British Columbia, Vancouver, BC. 131 pp.
Ferguson, H.M. and B.E. Johnston. 2000. In Press. Update COSEWIC status report on the Coastal giant salamander Dicamptodon tenebrosus in COSEWIC assessment and update status report on the Coastal giant salamander Dicamptodon tenebrosus in Canada . Committee on the Status of Endangered Wildlife in Canada. Ottawa. 1-37pp.
Good, D.A. 1989. Hybridization and cryptic species in Dicamptodon (Caudata: Dicamptodontidae). Evolution 43:728-744.
Govindarajulu, Purnima. Personal communication. Biologist. B.C. Ministry of Environment. Victoria, B.C.
Green, D.M. 1999. British Columbia Amphibians: A taxonomic catalogue. B.C. Minist. Environ., Lands and Parks, Victoria. Wildl. Bull. No. B-87. 22pp.
Haycock, R. 1991. Pacific giant salamander, Dicamptodon tenebrosus, status report. B.C. Minist. Environ., Lands and Parks, Wildl. Branch, Victoria. 53pp.
Johnston, B. 1998. Terrestrial Pacific Giant Salamanders (Dicamptodon tenebrosus Good): Natural history and their response to forest practices. M.Sc. Thesis, University of British Columbia, Vancouver, BC. 98 pp.
Matsuda, B.M., D.M. Green and P.T. Gregory. 2006. Royal BC Museum handbook amphibians and reptiles of British Columbia. Royal B.C. Mus., Victoria, BC. 266pp.
Richardson, J.S. and W.E. Neill. 1995. Biodiversity of stream invertebrates in streams used by Pacific Giant Salamanders. Unpublished report, FRBC Project OPS.EN-128.
Richardson, J.S. and W.E. Neill. 1998. Headwater amphibians and forestry in British Columbia: Pacific Giant Salamanders and Tailed Frogs. Northwest Science 72:122-123.
Richardson, J.S., and W.E. Neill. 1994. Distribution patterns of two montane stream amphibians and the effects of forest harvest: the Pacific Giant Salamander and Tailed Frog in southwestern British Columbia. Unpubl. rep., Westwater Res. Cent., Univ. B.C. 42pp.
Richardson, J.S., and W.E. Neill. 1997. Population persistence of the Pacific Giant Salamander in the face of land-use alterations. Unpubl. rep. submitted to the Habitat Conservation Trust Fund, Victoria, 14pp.
 

Please visit the website http://www.env.gov.bc.ca/cdc/Reports/status_data_fields_08.htm for information on how the CDC determines conservation status ranks. For global conservation status reports and ranks, please visit the NatureServe website http://www.natureserve.org/.

Suggested Citation:

B.C. Conservation Data Centre. 2016. Conservation Status Report: Dicamptodon tenebrosus. B.C. Minist. of Environment. Available: http://a100.gov.bc.ca/pub/eswp/ (accessed Jul 25, 2016).