Methods and summary data for limnology and food web structure in Lake Wenatchee, Washington (2010-2022) / by Donald J. McQueen, Braden Judson, Samantha Pham, Athena D. Ogden, Chelsea Mathieu, Lynnea Wiens. : Fs97-13/1497E-PDF

"The 2010-2022 food web data consistently suggest that Lake Wenatchee provides excellent habitat for juvenile Sockeye Salmon. Although the lake is oligotrophic, a unique mix of physical and biological conditions permits unusually high rates of Sockeye growth and production. These factors include (i) a well oxygenated, cold water hypolimnion, (ii) a ratio of edible to total phytoplankton which is exceptionally high, suggesting that most of the algal species found in Lake Wenatchee have sizes, shapes and digestibility that make them excellent food sources for freshwater zooplankton, and (iii) a zooplankton community that includes two large-bodied species (Daphnia schodleri and Hesperodiaptomus kenai), which provide excellent food sources for Sockeye fry. Through the period 2010-2022, the fall population density for Lake Wenatchee Sockeye fry averaged 2121 ha⁻¹. Age-0 Sockeye fry growth rates were variable, but in all years were higher than expected when compared to similar data from Osoyoos Lake. Years 2017-2019 and 2021-2022 bioenergetics-based production and consumption analysis showed that the percentage of prey production that was consumed per day by Sockeye fry was always much lower than the carrying capacity (i.e. 2017 = average 6.0% of prey production consumed per day, 2018 = 14.1%, 2019 = 14.0%, 2021 = 25.5%, 2022 = 5.1%). In no case was there any indication that consumption by age-0 and age-1 Sockeye Salmon fry was capable of limiting prey availability. We conclude that for the summer-early fall period, Lake Wenatchee has unused zooplankton production capacity that could be consumed by Sockeye fry. We suggest that the lake would be able to support September Sockeye fry population densities of 4000 ha ⁻¹, and that the lake could be managed for that density"--Abstract, page viii.

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