Energy density of fish within an aquaculture experiment

Abstract

Understanding how small-bodied fish are affected by aquaculture is important to help complete the picture on how aquaculture affects all levels of the ecosystem. I analysed the energy density for small-bodied fish in the presence of aquaculture. The experiment was done in a whole lake ecosystem within the boreal shield. This study focused specifically on finescale dace within two similar lakes; Lake 375 had aquaculture operating for 5 years and Lake 373 was monitored as a reference lake. Aquaculture likely had a positive impact on the energy density of finescale dace as they had access to an increased food source. While the energy density of minnows was higher in Lake 375 than Lake 373, there was a higher overwinter mortality rate in Lake 375. Based on findings presented here and from information reported elsewhere, I conclude that previously reported minnow overwinter mortality was largely due to an increase of predation of minnows from lake trout, rather than due to energetic deficits. While aquaculture appears to benefit the minnows where they displayed increased energy density and population densities, overwinter mortality may cause the minnow population densities to become unpredictable and volatile with an aquaculture operation.