Development of sustainable fisheries harvesting practices across Canada and worldwide depends heavily on sound scientific principles and evidence-based knowledge. Fisheries science has advanced towards fulfilling this need, but it has traditionally relied on ecological principles only. Through selectivity, such as size-selective harvesting, fisheries also induce evolutionary changes and these can subsequently elicit ecological change on short time scales (in some cases equal to or exceeding the changes brought on by classical ecological effects). Growing concern has been expressed for more than a decade that selectivity may directly or indirectly affect fisheries persistence and productivity, and ecosystem functioning upon which the fishing industry depends. Remarkably, however, there have been no comprehensive, experimentally-replicated assessments of these claims in nature. Hence, a critical knowledge gap remains for understanding how to enhance harvesting practices whilst maintaining biodiversity and ecosystem services.
We have recently initiated a large scale harvest selection experiment based on experimentally-controlled depletions across a series of closed, natural trout populations. Our project will take advantage of the mandate of Parks Canada to actively restore previously fishless alpine lakes where non-native trout were introduced 80-100 years ago.
Hence it provides an exceptional opportunity to conduct replicated depletion of natural populations of a socio-economically important fish species groups (salmonids) where they will be removed anyways. These depletions will be used to explore several untested hypotheses about the effects of size-selective harvesting on fisheries productivity and ecosystem function.