Most processes affecting a fish is determined by its body size rather than its age: consumption, mortality, maturation, fecundity, fish gear selectivity, etc. Moreover, measurements of body size are easy, accurate, and abundant, while measurements of age are costly and prone to error. In this work we make a systematic comparison of age- and size-based theory, and analyses strengths and weaknesses of either approach. Because size-based theory is axiomatic it is deeper and provides a unified framework for calculating the fisheries reference points, data-poor stock assessments, and fisheries induced evolution. This “Food for Thought” article in ICES Journal of Marine Science provides an introduction to size-based theory for modern fisheries advice.
K H Andersen (2020) Size-based theory for fisheries advice, ICES Journal of Marine Science.https://doi.org/10.1093/icesjms/fsaa157
The theory is demonstrated in our web-apps: http://oceanlife.dtuaqua.dk/Fish and https://www.stockassessment.org/spectrum