A comparative bioenergetics analysis of seasonal growth of juvenile Sockeye Salmon and their consumption of zooplankton in Great Central Lake and Sproat Lake, British Columbia, during 1999 / K.D. Hyatt... : Fs97-6/3159E-PDF

"Great Central Lake (GCL) and Sproat Lake are important Vancouver Island sockeye salmon nursery lakes. In most years since 1970, GCL has been treated with inorganic fertilizer additions and Sproat Lake has not. Our goal in 1999 was to estimate sockeye fry carrying capacity for both lakes. Our method was to compare consumption of zooplankton by juvenile sockeye with production by all of the zooplankton species observed in their diets. We found that GCL fry consumption averaged 130 g ha-1 d-1 wet weight (ww), which equalled 0.5% d-1 of prey standing stock and 8 to 81% d-1 of prey production. Sproat Lake fry consumed 400 g ha-1 d-1 ww in the spring declining through the summer-fall to < 100 g ha-1 d-1 ww, averaging 1.1% d-1 of prey standing stock and 2 to >100% d-1 of prey production. We conclude that in both lakes there was excess capacity for increased fry densities, and that the fall was the period when consumption by fish was most likely to exceed production by their zooplankton prey"--Abstract.

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