Earlier migration timing of salmonids: an adaptation to climate change or maladaptation to fishery?

Recent studies reporting shifts in the timing of salmonid migrations have suggested global warming to be a cause. However, the specific mechanisms underlining the evolution of earlier-migration timing in salmonid fishes are unknown. In this paper, I present a hypothesis by which fishery-induced selection works to advance the timing of salmonid migration, given the timing of migration and breeding are genetically controlled heritable traits. Although late-spawning salmon brood lines enter rivers after early spawning brood lines, there is evidence that all brood lines arrive in coastal fishing grounds at similar times. As such, late-spawning brood lines would be fished for longer periods of time, with their increased harvest rate imposing directional selection on earlier-spawning brood lines. Thus, fisheries-induced evolution could favor the earlier timing of river entry to escape coastal fisheries. Should earlier migration timing not be an adaptation to global warmingď žshould it be a maladaptation to fisheries-induced selection insteadď žthen it will have a negative impact on the sustainability of salmonid resources.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author