Influence of Population Density on the Evolution of Morphometric Parameters of Haliotis tuberculata Linnaeus 1758 Under Controlled Culture in Senegal

Abstract

This experiment was carried out in order to know the variation of the morphometric relation between the length and the width of the shell of abalone Haliotis tuberculata as well as the evolution of the factor of condition.Haliotis tuberculata used in the study is a gastropod that belongs to the order Vetigastropoda, and the family Haliotidae. 135 abalones with an average weight of 5.55±1.24 g, an average length and shell width of 3.14±0.23 cm and 2.12±0.18 cm were selected for the experiment.These individuals were divided into three different densities (10, 15, 20 individuals) in nine (9) plastic tanks with a base area of 0.15 m2 of 3 tanks per density. The abalones from each tank were fed 70% of their body weight with available macroalgae such as Ulva lactuca and Dictiopeterus sp. Morphometric relationships that include the relationships between length-width and condition factor were determinedAt the end of 12 months of experimentation, changes in length, width, and annual average weight as a function of density indicate that low stocking densities favor a faster increase in these variables (length, width, and weight). The analysis of these relationships indicates a strong correlation between the length and width of the Haliotis tuberculata shell. However, it is noted the correlation between these two variables decreases inversely with density. The average values of the condition factor are 18.89 ± 0.96, 18.72 ± 1.18 and 18.59 ± 1.14 for densities D10, D15 and D20 respectively. Analysis of the results of this study shows that when population density becomes too high, the growth of H. tuberculata is slowed down both in weight and in size. The condition factor analysis also indicates that the best biological performance is obtained at the lowest density (D10) thus inducing better growth.