Opportunistic exploitation: an overlooked pathway to extinction
Branch, TA, Lobo, AS & Purcell, SW 2013, 'Opportunistic exploitation: an overlooked pathway to extinction', Trends in Ecology & Evolution, vol. 28, no.7, pp. 409-413.
Published version available from: http://dx.doi.org/10.1016/j.tree.2013.03.003
- • Opportunistic exploitation of high-value species may occur in multispecies systems.
- • Targeting common species subsidizes continued depletion of high-value species.
- • This pathway appears widespread but underappreciated, with many case studies.
- • Ecological parallels include apparent competition, hyperpredation, and predator pits.
- • Managers should protect high-value species exploited with other species.
How can species be exploited economically to extinction? Past single-species hypotheses examining the economic plausibility of exploiting rare species have argued that the escalating value of rarity allows extinction to be profitable. We describe an alternative pathway toward extinction in multispecies exploitation systems, termed ‘opportunistic exploitation’. In this mode, highly valued species that are targeted first by fishing, hunting, and logging become rare, but their populations can decline further through opportunistic exploitation while more common but less desirable species are targeted. Effectively, expanding exploitation to more species subsidizes the eventual extinction of valuable species at low densities. Managers need to recognize conditions that permit opportunistic depletion and pass regulations to protect highly desirable species when exploitation can expand to other species.