ISSN: 2639-216X
Authors: Perez-Hernandez MA, Salgado-Ugarte IH*, Saito-Quezada VM, Pacheco-Marin R and Chirino-Gonzalez A
Background: The study of reproduction and condition are fundamental topics in fisheries science. To this aim, there are several methods including Gonadosomatic index, Condition factors (Fulton, Ricker, relative) and hepatosomatic index. These traditional methods present several drawbacks (ratio indices with variability and distribution problems; assumption of linear relationships and of independence from length, focus on the intercept of linear models, etc.). In this study, we present an application of the multivariate analysis of covariance (MANCOVA) to analyze reproduction and condition of Bairdiella chrysoura from Tampamachoco Lagoon compared with some traditional indexes. Methods: This comparison takes into account the biological data (lengths and weights) collection of 9,505 individuals of B. chrysoura registered during an annual period (May 1990- June 1991) at five localities in the Western side of the Tampamachoco Lagoon, Mexico. We compared Gonadosomatic index, Relative Condition Factor and Hepatosomatic index values to lengthadjusted means of gonad, eviscerated and liver weights from the multivariate analysis of covariance (MANCOVA) of females, males and indeterminate sex individuals. Results: High gonad, low hepatic and condition mean values (adjusted by MANCOVA) indicated the spawning period (February to March). The opposite trend among gonad weight with both, liver and somatic weights appears to indicate the metabolism focusing on gonad development for the onset of the spawning season. The patterns described by the adjusted means from MANCOVA were highly correlated and synchronic to the traditional index values. Conclusions: Therefore, the length-adjusted mean values of gonad, eviscerated body, and liver weights represent a useful alternative to the common ratio based estimators.
Keywords: Gonadosomatic Index; Condition Factor; Covariate Adjusted Means; Silver Perch; Morphometric Indexes
