Kinbasket Sturgeon Recolonization Risk Assessment and Habitat Suitability

Author: Westslope Fisheries Ltd

Habitat:The upper Columbia River has sufficient and prolonged scouring flows (maximum mean daily 1300 cms; 40-60 days mean flows > 500 cms) that approach sturgeon spawning flows in the Nechako (pre-dam) and Kootenai Rivers, providing freshly deposited and/or scoured substrates for incubating eggs and free-embryo hiding habitats. The unique and extensive wetland area between Radium and Donald allows the upper Columbia to be significantly warmer than other large river tributaries in the Kinbasket region and temperatures are optimal for sturgeon egg incubation and rearing (14-16 C). The approximately 40 km of river from Golden (at the Kicking Horse River) downstream to Redgrave had mean depths (2.8-6.45 m), near bottom velocities (0.82 to 2.31 m/s), substrates (gravel/sand/cobble) and turbidities (mean 13-126 NTU) sufficient to support spawning adults and the subsequent early life stages.

Water contaminants Analysis: The upper Columbia River was free of organochlorines (PCB’s), which adversely affect the growth and reproductive physiology of sturgeon. With the exception of the sediment arsenic at Golden, the region also appears free of any metal contaminants that would impede the hatching and early development of White Sturgeon eggs and larvae. In situ egg survival rates at Redgrave (range 36-73%) were comparable to field studies reported elsewhere in the Columbia River. In addition, this region offered suitable food types (crustaceans and Diptera pupae and larvae) and sizes (< 4mm) for the onset of exogenous feeding and subsequent developmental stages. White Sturgeon egg survival: In 2011, survival rates for White Sturgeon eggs placed in situ at four locations in the Upper Columbia River were highest at Redgrave (36-73%) and lowest at Golden (1-5%) (Table 3.5). Food availability : Samples from sites in the upper Columbia indicated the presence of preferred invertebrate species at appropriate sizes for the onset of exogenous feeding (i.e., 125 µm) and subsequent developmental stages (i.e., 125 µm to 4mm; Table 3.4). Diptera spp. (63%) were the most abundant food type throughout the study area and were comprised primarily of Chironomidae, Simulidae, and Ceratopogonidae pupae and larvae (Appendix D). Crustaceans (Cladocera, Daphinidae and copepods) were the second most abundant food type in the samples collected and may be a suitable food type given the dominance of crustaceans in the lower Columbia (i.e., Corophium spp.). With an estimated (all ages) 8.0 to 10.8 million kokanee in Kinbasket reservoir and a spawning escapement to the upper Columbia River of approximately one million (Westover 2003), the region has suitable prey availability at the onset of exogenous feeding and for young of the year and juvenile White Sturgeon.

Habitat:The upper Columbia River has sufficient and prolonged scouring flows (maximum mean daily 1300 cms; 40-60 days mean flows > 500 cms) that approach sturgeon spawning flows in the Nechako (pre-dam) and Kootenai Rivers, providing freshly deposited and/or scoured substrates for incubating eggs and free-embryo hiding habitats. The unique and extensive wetland area between Radium and Donald allows the upper Columbia to be significantly warmer than other large river tributaries in the Kinbasket region and temperatures are optimal for sturgeon egg incubation and rearing (14-16 C). The approximately 40 km of river from Golden (at the Kicking Horse River) downstream to Redgrave had mean depths (2.8-6.45 m), near bottom velocities (0.82 to 2.31 m/s), substrates (gravel/sand/cobble) and turbidities (mean 13-126 NTU) sufficient to support spawning adults and the subsequent early life stages.

Water contaminants Analysis: The upper Columbia River was free of organochlorines (PCB’s), which adversely affect the growth and reproductive physiology of sturgeon. With the exception of the sediment arsenic at Golden, the region also appears free of any metal contaminants that would impede the hatching and early development of White Sturgeon eggs and larvae. In situ egg survival rates at Redgrave (range 36-73%) were comparable to field studies reported elsewhere in the Columbia River. In addition, this region offered suitable food types (crustaceans and Diptera pupae and larvae) and sizes (< 4mm) for the onset of exogenous feeding and subsequent developmental stages. White Sturgeon egg survival: In 2011, survival rates for White Sturgeon eggs placed in situ at four locations in the Upper Columbia River were highest at Redgrave (36-73%) and lowest at Golden (1-5%) (Table 3.5). Food availability : Samples from sites in the upper Columbia indicated the presence of preferred invertebrate species at appropriate sizes for the onset of exogenous feeding (i.e., 125 µm) and subsequent developmental stages (i.e., 125 µm to 4mm; Table 3.4). Diptera spp. (63%) were the most abundant food type throughout the study area and were comprised primarily of Chironomidae, Simulidae, and Ceratopogonidae pupae and larvae (Appendix D). Crustaceans (Cladocera, Daphinidae and copepods) were the second most abundant food type in the samples collected and may be a suitable food type given the dominance of crustaceans in the lower Columbia (i.e., Corophium spp.). With an estimated (all ages) 8.0 to 10.8 million kokanee in Kinbasket reservoir and a spawning escapement to the upper Columbia River of approximately one million (Westover 2003), the region has suitable prey availability at the onset of exogenous feeding and for young of the year and juvenile White Sturgeon.