Comments on the calculation of the specific growth rate in experiments with untagged individuals

Authors

  • Lorenzo Márquez Núcleo de Investigación en Producción Alimentaria, Escuela de Acuicultura, Universidad Católica de Temuco
  • Gabriel A. Morales Departamento de Producción Animal, Universidad de Buenos Aires
  • Miguel Sáenz de Rodrigáñez Grupo de Nutrición y Alimentación Animal, Universidad de Almería
  • Eduardo Almansa Centro Oceanográfico de Canarias, Instituto Español de Oceanografía
  • Francisco J. Moyano Grupo de Nutrición y Alimentación Animal, Universidad de Almería
  • Manuel Díaz Grupo de Nutrición y Alimentación Animal, Universidad de Almería

DOI:

https://doi.org/10.3989/scimar.04303.30A

Keywords:

growth rate, corrections, aquatic organisms, experimental cultures, tagging, mortality

Abstract


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.

Downloads

Download data is not yet available.

Published

2015-12-30

How to Cite

1.
Márquez L, Morales GA, Sáenz de Rodrigáñez M, Almansa E, Moyano FJ, Díaz M. Comments on the calculation of the specific growth rate in experiments with untagged individuals. scimar [Internet]. 2015Dec.30 [cited 2022Aug.17];79(4):505-8. Available from: https://scientiamarina.revistas.csic.es/index.php/scientiamarina/article/view/1610

Issue

Section

News & Comments