Description mathématique de la croissance de Lesueurigobius friesii (Teleostei, Gobiidae). Essai de synthèse

A population of the burrowing goby Lesueurigobius friesii was studied from 1974 to 1979, at a sampling station located on a Nephrops ground in the northem Bay of Biscay, off the south coast ofBrittany; samples were collected close to a muddy bottom, at depths ranging from 80 to 100 m. Data on demographie structures were obtained by two independent exercises: examination of oto1iths and the analysis of length-frequency distributions. The fish attains a standard length of at !east 71 mm and an age of 6 years. Most growth takes place during the first three years of !ife, and proceeds very slowly thereafter. The state of gonad development was assessed qualitatively by visual inspection of the body cavity of females; spawning occurs in spring, and by July 61 of the 62 females examined were spent. During that month, small fish of the 0 year-class appear in the catches. One objective of the study is to provide a picture of the average growth pattern of the population; accordingly, data from equivalent months over the sampling period were combined, and the Von Bertalanffy growth curve was fitted by !east squares regression techniques involving no transformation of variates. Published data for a Scottish population of Fries'goby were also taken into account and processed in the same manner. The values obtained for the growth parameters (K and L,:J were used as a basis for comparison between the two stocks. In addition, the study proposes a new method for the comparison of growth curves, involving a computer simulation reflecting the variability of standard length considered as a random variable. The metabolic interpretation of the results is discussed, and the limits of the explanatory power of the model are emphasized.