University Of Tasmania

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Ecological consequences of body size decline in harvested fish species: positive feedback loops in trophic interactions amplify human impact

journal contribution
posted on 2023-05-19, 08:52 authored by Asta AudzijonyteAsta Audzijonyte, Kuparinen, A, Gorton, R, Elizabeth FultonElizabeth Fulton
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.


Publication title

Biology Letters



Article number









Institute for Marine and Antarctic Studies


The Royal Society Publishing

Place of publication

United Kingdom

Rights statement

Copyright 2013 The Author(s)

Repository Status

  • Restricted

Socio-economic Objectives

Understanding climate change not elsewhere classified