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COSEWIC Assessment and Update Status Report on the Nooksack dace in Canada


Global Range

Nooksack dace are restricted to western Washington State and southwestern British Columbia (Figure 2) where they inhabit the drainages of the east shore of Puget Sound, the western side of the Olympic Peninsula and the Fraser River Valley. The historical range is unknown, but unlikely to have been much more extensive as the Columbia-Fraser form of R. cataractae occupy drainages to the west and north with a zone of past or present overlap (see Genetic Description) and other members of the same clade occupy drainages south of the Columbia River (McPhail, pers. comm. 2006).

Figure 2: The Global Range of the Nooksack Dace is Restricted to Northwestern Washington State and the Fraser River Valley in Southwestern British Columbia

Figure 2: The global range of the Nooksack dace is restricted to northwestern WashingtonState and the Fraser River Valley in southwestern British Columbia.

Adapted from McPhail (1997) and Mongillo and Hallock (1997).

Canadian Range

Within Canada Nooksack dace occupy a restricted range consisting of four creeks in two major watersheds of the Fraser Valley (Fig. 3). Three of the creeks flow south into Washington State’s Nooksack River (Bertrand Creek, Pepin Creek and Fishtrap Creek). The fourth population, discovered in 2004, occupies the Brunette River, a tributary of the lower Fraser River. The nearby Coquitlam and Alouette Rivers, also tributary to the Fraser River, contain either sympatric populations or introgressed hybrids of Nooksack dace and Columbia-Fraser R. cataractae (see Genetic Description).

The extent of occurrence in Canada comprises 630 km2, or 4.3 percent of the global extent.  Potential habitat, defined as the total riffle area in reaches containing more than 10 percent riffle by length, totals 7 328 m2 in three of the four Canadian populations (Table 1). Much of this habitat is currently unoccupied due to seasonal drying, compaction with silt or beaver impoundment. Habitat in the fourth occupied watershed, the Brunette River, has yet to be surveyed, but the total riffle area available is 20 155 m2.  This gives a total riffle area (area of occupancy) of 0.03 km2. The area of occupation in Washington State is unknown. Area of occupancy estimated from an overlaid grid of cell size one km2 is in the order of 14 km2.

Table 1: Potential Habitat and Population Sizes for Confirmed Nooksack Dace Populations in Canada
DrainageLength of Riffle (m)Area of Riffle (m2)Maximum PopulationCPUE RatioAdjusted Estimate
Bertrand Creek1 1992 9965 70018.95 700
Pepin Creek1 0502 3004 4002.7800
Fishtrap Creek1 0162 0323 9001300
Brunette River*10 47320 15538 300NANA
Total13 73827 48352 300NANA

*Pearson, Unpublished data
Potential habitat consists of riffle areas in reaches containing more than 10% riffle by length. Maximum population estimates are products of density in high quality habitat (1.9 per m2, Inglis et al., 1994) and available riffle area. A CPUE-based estimate of relative abundance among watersheds (Pearson, 2004) is used to calculate the adjusted estimate. See Population Sizes and Trends for discussion.

The existence of unknown populations in other Fraser River tributaries seems plausible in light of the recent confirmation of the Brunette River population. Searches of occurrence records for R. cataractae in the Fraser Valley using the UBC Fish Museum database and the British Columbia Fisheries Inventory Summary System and the Royal British Columbia Museum records yielded putative records from 36 sites in the Fraser Valley (Table 2). Those from areas not yet genetically characterized are shown in Figure 3.

Within watersheds Nooksack dace distribution is extremely clumped. Pearson (2004) compared catch per unit effort (CPUE; mean number of fish per trap; 24 h sets) in 72 reaches of the Nooksack River tributaries. CPUE was zero in most (41) reaches and high densities (CPUE>0.25 fish per trap) were found in only 8 reaches, 6 of which are contiguous in lower Bertrand Creek. He estimated that this 5 km stretch of channel constituting just 12.5% of mainstem length in the Nooksack River tributaries contained more than 70% of their Nooksack dace.

Historical changes in the Canadian distribution are poorly documented, but a general decline over at least the past half-century seems likely. McPhail (1997) reports that Nooksack dace were extirpated from some headwater tributaries of Bertrand and Fishtrap creeks between the late 1960s and the mid-1990s. Pearson (2004) found them only in the main stems of these creeks, and observed that most of the tributaries run dry in late summer.

Table 2: Records of Rhinichthys cataractae in the Fraser Valley on the UBC Fish Museum Database,1 the British Columbia Fisheries Inventory Summary System (FISS)2 and the Royal British Columbia Museum (RBCM)
SiteDrainageLocationYearEastingNorthingReferenceHaplotypes Present3
1Norrish Creek2.6 km upstream1959  UBC 59-0602CF
2Norrish Creek8 km upstream1959  UBC 59-0600CF
3Alouette River224 ST19985291105453616FISS HQ2030N/CF
4Alouette River232 St1980  UBC 82-0012N/CF
5Alouette RiverAlouette Lake outlet19965371705459510FISS HQ0717N/CF
6Bertrand CreekOtter Road1963  UBC 76-0027N
7Bertrand Creek 19935373715434835FISS HQ0517N
8Brunette RiverStill Creek at Hwy 71956  UBC 56-0122N
9Brunette RiverUnknown1953  UBC55-0009N
10Coquitlam RiverHwy 7 bridge1956  UBC 56-0412N /CF
11Coquitlam RiverUnknown1951  UBC 55-0008N/CF
12Coquitlam River 19965172555465878FISS HQ0498N/CF
13Coquihalla RiverNear mouth1956  UBC 59-0446?
14Fraser RiverDewdney (Nicomen Slough?)1959  UBC 59-0601?
15Fraser RiverKirkland Island19784912155439571FISS HQ0444?
16Fraser RiverMouth of Vedder1959  UBC 59-0608?
17Fraser RiverN of Chilliwack20005727835448220FISS HQ1489?
18Fraser RiverN of Chilliwack20005749385451237FISS HQ1489?
19Fraser RiverN of Chilliwack20005767655450636FISS HQ1489?
20Fraser RiverN of Chilliwack20005765335452159FISS HQ1489?
21Fraser RiverN of Chilliwack20005777675451240FISS HQ1489?
22Fraser RiverN of Chilliwack20005783635453036FISS HQ1489?
23Fraser RiverN of Chilliwack20005804035452854FISS HQ1489?
24Fraser RiverCoquihalla Mouth1956  UBC 59-0002?
25Fraser RiverS of Agassiz20005866175452439FISS HQ1489?
26Fraser RiverS of Agassiz20005905445451894FISS HQ1489?
27Fraser RiverS of Agassiz20005936785453684FISS HQ1489?
28Kanaka CreekLower reaches?  McPhail pers. comm.?
29Pitt RiverMainstem19915280685466523FISS HQ0435?
30Silverdale Creek4 19545471005443000UBC 58-0552?
31Vedder RiverCultus Lake outlet19955743545436388FISS 2FBSRY?
32Fraser RiverAgassiz1987  RBCM 987-00234-003?
33Fraser RiverAgassiz1987  RBCM 987-00235-004?
34Fraser RiverAgassiz1987  RBVM 987-00236-001?
35Fraser RiverHerling Island1992  RBCM 992-00227-002?
36Fraser RiverChilliwack1987  RBCM 987-00233-001?

3 As identified by McPhail:     CF = Columbia-Fraser   N = Nooksack    ?= not tested
4 Mission

Figure 3: In Canada, Nooksack Dace Populations are Confirmed in the Brunette River (A, 2004), Bertrand Creek (B, 2005), Pepin Creek (C, 2004), and Fishtrap Creek (D, 2004)

Figure 3: In Canada, Nooksack dace populations are confirmed in the Brunette River (A, 2004), Bertrand Creek (B, 2005), Pepin Creek (C, 2004), and Fishtrap Creek (D, 2004).

Norrish Creek (G) contains the Columbia-Fraser form of R. cataractae, while the Coquitlam River (E. 2004) and Alouette River (F, 2005) contain either sympatric populations or introgressed hybrids of the two types (J.D. McPhail unpubl. data). Years refer to date of most recent captures (Pearson, unpubl. data). Numbers refer to putative R. cataractae records from other watersheds as detailed in Table 2.