Understanding the Factors Affecting Variation in Length-Weight Relationship in Gangetic hairfin anchovy, Setipinna phasa (Hamilton, 1822) from Estuarine and Riverine Ecosystems of Ganga Basin using Generalized Linear Model

Length-weight relationship is an important tool in fish biology that provides insights into growth patterns of the fish and environmental conditions in its habitat. In the current study, the variability of the length-weight relationship of the Gangetic hairfin anchovy, Setipinna phasa (Hamilton, 1822) was correlated with the prevailing environmental factors. A total of n = 341 individuals of S. phasa (Engraulidae) were collected from the Ganga River and the Hooghly estuary. The changes in their growth in relation to their ecosystem type, developmental stages, and gender were studied. The fish living in estuarine waters showed an isometric growth pattern, characterized by smaller and plumper fish than those found in riverine waters, where a negative allometric growth pattern was observed. This change may be attributed to the variations in the diverse ecosystems. The b-values were found to be higher for juveniles and female individuals. The results of the Generalized Linear Model (GLM) analysis showed that the b-values were significantly influenced by the ecosystem type, environmental variables, developmental stages and gender. The results have significant implications for managing, conserving, and prioritizing fish populations for sustainable utilization in their respective habitats.