Reporting Fish Growth: A Review of the Basics¹

Abstract

Aquaculturists typically report growth using absolute (g/d), relative (% increase in body weight), and specific growth rates (%d). Less frequently, von Bertalanffy Growth Functions (VBGF) are used. Each of these rates is a numerical representation of growth which assumes a specific relationship between size and time (linear, exponential, or asymptotic). Aquaculturists typically determine size at time throughout their experiments. Unfortunately, the intermediate data points are usually ignored when computing growth rates (except for VBGF) and the appropriateness of the method for calculating growth for a particular data set is not tested. This paper reviews the basis and computation of each of the growth rates in an effort to encourage aquaculturists to use the appropriate growth rates.

A mark-recapture study of hatchery-reared juvenile European lobsters, Homarus gammarus, released at the rocky island of Helgoland (German Bight, North Sea) from 2000 to 2009

“…The absolute growth rates per year (AGR) (carapace length (CL) and weight (W)) for age, sexes and cohorts were used to evaluate growth according to Hopkins (1992).…”

Impaired growth and erythrocyte nuclear lesions of immature Oreochromis niloticus exposed to waterborne crude oil: Persistent responses

“…Growth indices were estimated according to Hopkins (1992), and length growth rate (mm/day) and weight growth rate (g/day) were estimated for intervals between day one and respective sampling time points. Specific growth rates (SGR) of weight and length were calculated for 90-day experimental duration using SGRW = 100 (ln W2-ln W1)/(t2-t1) and SGRL=100 (ln L2-ln L1)/(t2-t1) respectively where 2 and 1 represent final and initial status at times t2 and t1.…”

Utilización de la proteína dietaría por alevinos de la gamitana, Colossoma macropomum, alimentados con dietas isocalóricas

“…El comportamiento productivo de la gamitana se evaluó a través de la ganancia de peso (Hopkins 1992), conversión alimenticia, proteína retenida, energía retenida (Reinitz & Hitzel 1980) y la razón de eficiencia proteica (Hepher 1993).…”