The analysis of Chilean lakes points out important uncertainties that could he reduced by targeted research. We do not know the critical loading level of nutrients that destabilizes lake ecosystems and impairs their use. The lakes can probably tolerate some enrichment, but how does risk rise with loading? What are the implications of human population growth for water quality, and what steps are necessary to maintain nutrient loading below critical levels? So far, aquaculture has reduced fishing pressure on the native piscivore. What are the consequences for populations of the native planktivores and benthos? How will naturalization of exotic salmonids alter the food web and overall fishery productivity? What pressures will increasing human populations place on aquaculture and the fishery?
Rapid and undesirable changes in the lakes could be caused by events that are essentially unpredictable. Political pressures could develop to increase stocking of salmonids. An unforeseen species introduction could dramatically alter the food web, with cascading consequences for biodiversity, water quality and fishery productivity. Disease could decimate the hatchery stock, affecting aquaculture and/or native fish stocks. The only prediction we can make about surprises is that they will occur. Coping with surprise requires the capacity and flexibility to innovate when surprised. Decision-making may be aided by scientific information available at the time of the surprise, and responsive research to understand the new problem may be helpful, but by definition surprises are not anticipated, and management will usually have to respond while new research is barely underway.
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