Comments on the calculation of the specific growth rate in experiments with untagged individuals
Keywords:growth rate, corrections, aquatic organisms, experimental cultures, tagging, mortality
The specific growth rate, G, is widely used in articles dealing with the growth of aquatic organisms under experimental conditions. When individuals are untagged, the arithmetic mean of G for a group of animals must be calculated from weight geometric means, not from arithmetic means. The type of weight mean used in articles to calculate the arithmetic mean of G is usually not reported, and an extended use of weight arithmetic means is common. The arithmetic mean of G so calculated is biased according to the increment in the squared coefficient of variation of body weights. Another potential bias in the calculation of the arithmetic mean of G is size-dependent mortality; this bias cannot be avoided when individuals are untagged, but maximal and minimal values can be obtained. In summary, in view of these analytical results, it seems prudent to calculate the arithmetic mean of G for a group of untagged animals from geometric means of weights, and to estimate the maximal error due to the possibility of size-dependent mortality whenever possible.
How to Cite
Copyright (c) 2015 Consejo Superior de Investigaciones Científicas (CSIC)
This work is licensed under a Creative Commons Attribution 4.0 International License.© CSIC. Manuscripts published in both the printed and online versions of this Journal are the property of Consejo Superior de Investigaciones Científicas, and quoting this source is a requirement for any partial or full reproduction.
All contents of this electronic edition, except where otherwise noted, are distributed under a “Creative Commons Attribution 4.0 International” (CC BY 4.0) License. You may read here the basic information and the legal text of the license. The indication of the CC BY 4.0 License must be expressly stated in this way when necessary.
Self-archiving in repositories, personal webpages or similar, of any version other than the published by the Editor, is not allowed.