Empirical Links Between Demography, Life History, and Recovery in Fishes
November 2, 2017
Jeffrey Hutchings
Studies on small and declining populations dominate research in conservation biology. This emphasis reflects two overarching frameworks: the small-population paradigm focuses on correlates of increased extinction probability; the declining-population paradigm directs attention to the causes and consequences of depletion. Neither, however, particularly informs research on the determinants, rate, or uncertainty of population increase. Compounding this deficiency is the problem that most meta-analyses used to detect Allee effects (declining per capita productivity with declining population size) have been fraught with theoretical and methodological limitations.
I adopt Jeffrey Hutchingsan alternative approach, examining the correlates of observed, rather than predicted, abundance trajectories for populations that have and have not recovered from depletion, despite threat mitigation. Based on these empirically based analyses, two key conclusions emerge for fishes that are inconsistent with prevailing scientific beliefs and perceptions.
Firstly, the greater the reduction in population size, the greater the likelihood that Allee effects impair recovery. Secondly, in contrast to multiple studies, life-history traits appear to be poor predictors of recovery when considered singly. In combination, however, a subset of traits provides compelling evidence for the hypothesis that rate of natural mortality (M), or a metric thereof, provides an empirically tractable and theoretically defensible predictor of recovery potential.
Bio
After obtaining a PhD at Memorial University of Newfoundland, Jeffrey Hutchings worked at Edinburgh University (Scotland) and Fisheries & Oceans Canada (St. John’s) before accepting a position at Dalhousie University, where he was recently (2016) appointed Dalhousie’s Killam Chair in Fish, Fisheries and Oceans. Since 2010, he has also held three academic positions in Norway. His work on fish ecology, evolution, and population dynamics has been published in more than 210 peer-reviewed scientific articles. He has chaired four national committees, including Canada’s science advisory body on species at risk (COSEWIC; 2006-2010). Since 1997, Hutchings has been invited to appear before 11 parliamentary Standing Committees. Co-founder and Past-President of the Canadian Society for Ecology and Evolution, he chaired the Royal Society of Canada Expert Panel (2012) on the effects of climate change, fisheries, and aquaculture on Canadian marine biodiversity. He was elected Fellow of the Royal Society of Canada (Academy of Science) in 2015.
