Humans are changing marine ecosystems worldwide, both directly through fishing and indirectly through climate change. One of the little explored outcomes of human-induced change involves the decreasing body sizes of fishes. We use a marine ecosystem model to explore how a slow (less than 0.1% per year) decrease in the length of five harvested species could affect species interactions, biomasses and yields.We find that even small decreases in fish sizes are amplified by positive feedback loops in the ecosystem and can lead to major changes in natural mortality. For some species, a total of 4 per cent decrease in length-at-age over 50 years resulted in 50 per cent increase in predation mortality. However, the magnitude and direction in predation mortality changes differed among species and one shrinking species even experienced reduced predation pressure. Nevertheless, 50 years of gradual decrease in body size resulted in 1-35% decrease in biomasses and catches of all shrinking species. Therefore, fisheries management practices that ignore contemporary life-history changes are likely to overestimate long-term yields and can lead to overfishing.

Item Type:	Refereed Article
Keywords:	climate change, contemporary evolution, ecosystem, harvesting, life-history, predator-prey interactions
Research Division:	Environmental Sciences
Research Group:	Ecological Applications
Research Field:	Ecological Impacts of Climate Change
Objective Division:	Environment
Objective Group:	Climate and Climate Change
Objective Field:	Climate and Climate Change not elsewhere classified
UTAS Author:	Audzijonyte, A (Dr Asta Audzijonyte)
UTAS Author:	Fulton, EA (Dr Elizabeth Fulton)
ID Code:	119518
Year Published:	2013
Web of Science® Times Cited:	55
Deposited By:	Ecology and Biodiversity
Deposited On:	2017-08-02
Last Modified:	2017-09-15
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