Fish & Wildlife , Ichthyoplankton and Zooplankton Sample Processing

2026-11-03

Task 1 – Process Bongo Net Tow Samples Process the catch in samples from ichthyoplankton tows made in Lake Roosevelt ( Columbia River , Washington ) using Bongo nets ( 0 . 6 m dia . mouth and either 333 or 500 µm mesh ) each year to : • Identify each fish to the lowest taxonomic level practical ( species for most ); • Enumerate each taxa ; • Measure each individual fish for total length ; and • Preserve each fish individually . Expect as many as 325 samples per year for three consecutive years . All samples will be preserved in 95 % ethanol . Each year ’ s samples will be delivered by July 1 of the sample year . To provide an indication of the level of effort required ; in 2025 there were 309 samples collected and a total of 3 , 843 ichthyplankton observed . The distribution of the catch by sample is provided in Figure 1 . Task 2 – Process Vertical Zooplankton Net Tow Samples Process the catch in 30 m vertical zooplankton tows ( 0 . 5 m dia mouth ; 50 µm mesh ) made in Lake Roosevelt ( Columbia River , Washington ) to : • Identify each zooplankter , including rotifers , to the lowest taxonomic level practical ; • Enumerate each taxon ( see below for sample splitting ); • Measure for length ( see below for subsampling ); and • Estimate biomass for each taxon . Expect as many as 65 samples per year for three consecutive years . All samples will be preserved in 95 % ethanol . Each year ’ s samples will be delivered by July 1 of the sample year . Enumerating all of the zooplankton may not be practical for most , if not all , samples . As such , describe the criteria that will be used for sample splitting , along with the proposed method for splitting and justification for the selection of that method . Similarly , measuring all zooplankton will not be practical for most , if not all , samples . As such , provide proposed sample sizes for zooplankton length measurements . Identify zooplankton species specific length measurements to be completed . Describe the method to be used to estimate the biomass of each taxon .

Washington

2026-05-14