Instream Flow Needs Analysis - Okanagan Basin Water Board

FINALOkanagan Basin Instream Flow NeedsTable 2.1.Equations used for predicting optimum flow for salmonid life stages from the mean annual discharge(MAD) of a stream and its latitude and/or longitude coordinates (from Hatfield and Bruce 2000).Adjusted R 2 values reported for regression models in Hatfield and Bruce (2000) were based on aresampling validation (i.e., bootstrapping). We used the species-specific regressions that had beendeveloped for Chinook salmon, rainbow trout, and steelhead trout, and used the “all salmonids pooled”regression for other salmonid species in the Okanagan (e.g., kokanee, sockeye salmon).Species Life stage Equation df Adjusted R 2Chinook Juvenile -0.998 + 0.939 . loge(MAD) 1, 51 0.705salmonSpawning -51.710 + 0.682 . loge(MAD) + 11.042 . loge(longitude) 2, 52 0.735Rainbow Juvenile -15.543 + 0.539 . loge(MAD) + 4.400 . loge(latitude) 2, 96 0.775troutSpawning -12.037 + 0.598 . loge(MAD) + 3.623 . loge(latitude) 2, 71 0.711Steelhead Juvenile -8.482 + 0.593 . loge(MAD) + 2.555 . loge(latitude) 2, 51 0.770troutSpawning -33.064 + 0.618 . loge(MAD) + 7.260 . loge(longitude) 2, 41 0.805All salmonids Juvenile -6.119 + 0.679 . loge(MAD) + 1.771 . loge(latitude) 2, 320 0.653pooled*Spawning -12.392 + 0.660 . loge(MAD) + 1.336 . loge(latitude) + 1.774 . loge(longitude) 3, 308 0.681*The “all salmonids pooled” regression was used for determining the optimal flows for sockeye, kokanee and coho salmon. Coho are notcurrently present within the Okanagan Basin but were evaluated for potential recovery needs.2.4.1 Fish presence/absenceDetermining the fish-bearing status of nodes in the Okanagan Basin area provides the foundation fordeveloping IFN recommended flows. Information on fish species presence at the nodes defined for theOkanagan Basin was extracted by ESSA staff from BC MOE'S Fish Inventory Data Queries(a100.gov.bc.ca/pub/fidq/fissSpeciesSelect.do) and Fish Wizard queries (www.fishwizard.com). Theseinitial results were tabulated and submitted to BC MOE, DFO, and ONA staff biologists for review andadjustment based on local knowledge. Reviews of fish distributions were provided by Jerry Mitchell (BCMOE, Penticton), Margot Stockwell (DFO, Nanaimo) and Carla Davis (ONA).Anadromous fishThree species of anadromous salmon currently exist in the Okanagan Basin: sockeye, steelhead andChinook. The Okanagan River sockeye population is one of only two populations of sockeye salmonremaining in the international Columbia River Basin. Okanagan steelhead have declined so precipitouslyin the U.S. Upper Columbia that they have been declared an endangered species (NOAA 2008 – UpperColumbia River Steelhead DPS) and until very recently little was known about their population size ordistribution within the Canadian portion of the Okanagan (Long et al. 2006). Okanagan Chinook,although once an important part of tribal fisheries in the Okanagan, have now declined to the point thatCanadian Okanagan Chinook have been designated as threatened by COSEWIC (COSEWIC 2006a) andare being considered for listing under SARA (DFO 2008). Coho and chum salmon, as well asanadromous white sturgeon and Pacific lamprey, were also historically indigenous to the OkanaganBasin but these have been extirpated from the Basin.Resident fishThere is a diverse mix of resident fish in the Okanagan Basin. The resident species of primarymanagement concern are kokanee and rainbow trout. Both species utilize many of the lakes and streamsthroughout the Basin. Other resident salmonids in the Basin include hatchery stocked lake trout,westslope cutthroat trout and brook trout, and possibly bull trout (Long 2003). Resident non-game fishESSA Technologies Ltd. & 16Solander Ecological Research