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Abstract

An extensive literature and debate exist on how and why temperature impacts animal, and especially ectotherm, body sizes. However, there remain considerable discrepancies and misunderstandings in the key definitions and concepts of body size used to describe observed temperature impacts across studies. For fish and other animals that continue growing throughout life, body size can be defined as size-at-maturity, adult size, asymptotic size, maximum observed size, population-averaged length or mass, or average size-at-(arbitrary)-age. These concepts of size are not equivalent, and temperature is likely to affect each in different ways. Some disagreement about temperature impacts on fish body sizes might relate to the different body size and growth metrics used, especially when combined with different biological scales (individual, population, or community) and empirical contexts (laboratory, field). Here, we review six common confusions associated with the measurement of "size" in fish and other water-breathing ectotherms and recommend consistent and accurate use of terms and methodology to ensure that studies of global warming impacts on fish sizes can be compared and interpreted unequivocally.

Keywords

"shrinking" fish; growth coefficient; human impacts; maximum and asymptotic size; temperature-size rule; von Bertalanffy growth curve

Published in

Global Change Biology
2025, volume: 31, number: 6, article number: e70296
Publisher: WILEY

SLU Authors

UKÄ Subject classification

Ecology
Environmental Sciences

Publication identifier

  • DOI: https://doi.org/10.1111/gcb.70296

Permanent link to this page (URI)

https://res.slu.se/id/publ/142723