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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: S2S3
Date Status Assigned: December 31, 2016
Date Last Reviewed: December 31, 2016
Reasons: This species has a small, restricted range and fragmented distribution.Threats were assessed as high due to logging that continues to degrade habitats across the species? range and from siltation of breeding streams resulting from erosion and surface run-off associated with roads and forestry activities (COSEWIC 2014k).
 
Range
Range Extent: C = 250-1,000 square km
Range Extent Estimate (km2): 760
Range Extent Comments: This species is found in southwestern B.C., extending from the west side of Vedder Mountain to the slopes east of Chilliwack Lake (COSEWIC 2014k). It is restricted to the Chilliwack River and nearby, smaller watersheds (Haycock 1991; Richardson and Neill 1995). The calculated total range extent is equal to 760 square km. (COSEWIC 2014k). 
 
Area of Occupancy: E = 26-125
Area of Occupancy Estimate: 83
Linear Distance of Occupancy: DE = 21-500
Area of Occupancy Comments: The estimated index of area of occupancy (IAO) is 332 km˛, based on 2 x 2 km grid cells. This value is most likely an underestimate (COSEWIC 2014k).
 
 
Occurrences & Population
Number of Occurrences: C = 21 - 80
Comments: "Based on data compiled in 2010 this species occupies approximately 75 individual streams and tributaries within about 15 stream systems or 4th order watersheds. During 2011 and 2012 surveys, additional sites where the species was present were identified" (COSEWIC 2014k). As of 2013, the Conservation Data Centre has the locations grouped into 26 mapped element occurrences.
Number of Occurrences with Good Viability / Ecological Integrity: Rank Factor not assessed
Number of Occurrences Appropriately Protected & Managed: CD = 4 - 40
Comments: "As of 2010, 25% of the total known occupied stream length is within designated Wildlife Habitat Areas established for the species under the Identified Wildlife Management Strategy and receives a degree of protection through associated General Wildlife Measures" (COSEWIC 2014k).
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). No estimates have been made since (COSEWIC 2014k).
 
Threats (to population, occurrences, or area affected)
Degree of Threat: B = High
Comments: "Main threats to Coastal Giant Salamanders are from logging that continues to degrade habitats across the species? Canadian range and from siltation of breeding streams resulting from erosion and surface run-off associated with roads and forestry activities. Urban development and run-of-river energy projects pose additional threats to local populations. The Coastal Giant Salamander occurs mainly in and around mid- elevation streams, and its occurrence and breeding activity, in particular in main stems at lower elevations, are curtailed by introduced predatory fish. Thus, even if forested stream buffers are left in otherwise deforested terrain, overland dispersal can be expected to be severely restricted, accentuating inter-stream isolation and population fragmentation. More frequent and severe droughts and flooding events are expected to accentuate impacts of human activities on these salamanders" (COSEWIC 2014k). 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 et al. 2013).
 
Trend (in population, range, area occupied, and/or condition of occurrences)
Short-Term Trend: FG = Decline of <30% to relatively stable
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 and there has been no new information on population sizes or trends since 2000 (COSEWIC 2014k). Based on the species? specific habitat requirements, habitat fragmentation, and continuing threats, a declining population trend that may exceed 30% is suspected, unless threats are adequately mitigated (COSEWIC 2014k).


 
Long-Term Trend: U = Unknown
 
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: Rank Factor not assessed
Other Rank Considerations:
 
Information Gaps
Research Needs: In 2015, Environmental DNA (eDNA) studies were successful in detecting the presence of D. tenbrosus at aquatic sites (Hobbs and Goldberg 2016). 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: Compared to some amphibian species, a relatively high number of detailed studies have focused on Coastal Giant Salamander in the Chilliwack Valley; the most recent survey by Dudaniec et al. in 2012 (COSEWIC 2014k). Continued monitoring is needed to establish trends.
 
Stewardship
Protection: This species is listed as Identified Wildlife under the Forest and Range Practices Act.
Management:
 
Version
Author: R. Haycock, S.Cannings, L. Ramsay (2005); L. Gelling (2010, 2016)
Date: September 27, 2016
 
References
COSEWIC. 2014k. COSEWIC assessment and status report on the Coastal Giant Salamander Dicamptodon tenebrosus in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. xii + 53 pp.
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.
Hobbs, J. and Goldberg, C. 2015. Pacific Water Shrew and Coastal Giant Salamander inventory and method assessment environmental DNA (eDNA) study. 
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 Conservation Status Ranks 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. 2017. Conservation Status Report: Dicamptodon tenebrosus. B.C. Minist. of Environment. Available: http://a100.gov.bc.ca/pub/eswp/ (accessed Jun 27, 2017).