Larval Lamprey Assessment at the Roza Dam Forebay and Yakima River Delta Region, 2015
Dates
Publication Date
2016-09
Summary
In 2015, Pacific Northwest National Laboratory and staff from the Yakama Nation conducted deep water larval lamprey surveys near the Roza Dam Diversion Fish Screening Facility and at the Yakima River delta region to determine lamprey occurrence and provide a general assessment of substrate composition. Results from surveys indicated that very few larval lamprey are inhabiting regions just upstream of the Roza Diversion facility although suitable substrates are present and abundant. At the Yakima River delta, larval lamprey searches were conducted at three general areas consisting of the main river channel and delta regions to the north of the mouth. Most of the substrates in this region had significant macrophyte growth over soft sand/silt [...]
Summary
In 2015, Pacific Northwest National Laboratory and staff from the Yakama Nation conducted deep water larval lamprey surveys near the Roza Dam Diversion Fish Screening Facility and at the Yakima River delta region to determine lamprey occurrence and provide a general assessment of substrate composition.
Results from surveys indicated that very few larval lamprey are inhabiting regions just upstream of the Roza Diversion facility although suitable substrates are present and abundant. At the Yakima River delta, larval lamprey searches were conducted at three general areas consisting of the main river channel and delta regions to the north of the mouth. Most of the substrates in this region had significant macrophyte growth over soft sand/silt sediments. A total of three larval lamprey were observed in a relatively small region along the north section of the delta region in water depths of approximately 6 m in Type I and II substrates. At the Roza Dam forebay, a total of four larval lamprey were observed in Type I and II substrates. Three of the four lamprey were found near the trash racks upstream from Screening Bay 5 at a water depth of 5.3 m, and the other was found ~515 m upstream from the facility at a water depth of 2.9 m.
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