BC Conservation Data Centre: Conservation Status Report
Dicamptodon tenebrosus
Coastal Giant Salamander
| Scientific Name: | Dicamptodon tenebrosus |
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| English Name: | Coastal Giant Salamander |
| English Name Synonyms: |
Pacific Giant Salamander
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| Provincial Status Summary | |
| Status: | S2S3 |
| Date Status Assigned: | December 31, 2016 |
| Date Last Reviewed: | January 20, 2022 |
| 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): | 765.79 |
| Range Extent Comments: |
After refining the CDC occurrence mapping for Dicamptodon tenebrosus in 2021, the total range extent was calculated to be 765.79 km2. This is not a significant change from what was known in 2014 (COSEWIC 2014k) and reflects refinement in line work rather than a range extension. This species is found in southwestern B.C., mainly along the Chilliwack River, extending from the west side of Vedder Mountain and Cultus Lake, to the slopes east of Chilliwack Lake, south to the border with the United States and north to Bridal Veil Creek. |
| Area of Occupancy (km2): | E = 26-125 |
| Area of Occupancy Estimate (km2): | 86 |
| Area of Occupancy Comments: | Based on CDC occurrence mapping completed November 2021, the Area of Occupancy is 344 km2 (86 2x2 km grid cells). |
| Occurrences & Population | |
| Number of Occurrences: | C = 21 - 80 |
| Comments: | As of 2021, the BC CDC has 30 Element Occurrences mapped (B.C. CDC 2021). |
| 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: |
There haven't been estimates of adults made since Ferguson and Johnstone (2000) provided 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 (COSEWIC 2014k). This is likely low as there have been new locations and extensions of known inhabitated streams since this time, however still likely below 100,000. 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: | 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: | Decline is largely unstudied and there has been no new information on population sizes or trends since 2000 (COSEWIC 2014k). Based on 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). As of this update, 2021, there has been no further monitoring to determine trends. |
| 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: | AB=Highly to moderately vulnerable. |
| Comments: | Ferguson (1998) and Johnstone (1998) show very low dispersal rates for larvae and terrestrial adults respectively. |
| Environmental Specificity: | B=Narrow. Specialist or community with key requirements common. |
| 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, 2021); L. Gelling (2010, 2016) |
| Date: | September 27, 2016 |
| References | |
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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.
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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.
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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.
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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.
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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.
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Good, D.A. 1989. Hybridization and cryptic species in Dicamptodon (Caudata: Dicamptodontidae). Evolution 43:728-744.
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Govindarajulu, Purnima. Personal communication. Biologist. B.C. Ministry of Environment. Victoria, B.C.
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Green, D.M. 1999. British Columbia Amphibians: A taxonomic catalogue. B.C. Minist. Environ., Lands and Parks, Victoria. Wildl. Bull. No. B-87. 22pp.
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Haycock, R. 1991. Pacific giant salamander, Dicamptodon tenebrosus, status report. B.C. Minist. Environ., Lands and Parks, Wildl. Branch, Victoria. 53pp.
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Hobbs, J. and Goldberg, C. 2015. Pacific Water Shrew and Coastal Giant Salamander inventory and method assessment environmental DNA (eDNA) study.
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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.
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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.
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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.
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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.
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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.
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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.
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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. 2016. Conservation Status Report: Dicamptodon tenebrosus. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Sep 18, 2024).