Understanding Relationship between Length and Weight with Otolith Dimension of Tenualosa ilisha from Hooghly River (India)

Abstract

The Indian hilsa shad, Tenualosa ilisha (Hamilton, 1822), is a highly valued fish of the Indo Pacific region. This paper represents the length-weight relationships (LWR), condition factor (K), relative condition factor (K_n), and otolith dimension of hilsa, throughout the Hooghly River (West Bengal) from January to December 2020. The value of exponent “b” in the equation W = cL^b was 2.6 for the species. It suggests the growth rate almost follows the cube law. Most of the population under study complied with the ideal b-value. Regression analysis indicated a high positive correlation between length and weight in the species (R² = 0.76). The K_n shows their general well-being to be good in the river. The relationships between total fish weight and otolith biometry parameters such as long arm (L.A) length, short arm (S.A) length, L.A/S.A, and diameter (D) were examined. Linear regressions have represented fish weight-otolith biometry relationships. Regression analysis indicated a strong positive relationship between body weight and otolith length (R² = 0.848), otolith diameter (R² = 0.803), and short arm length of otolith (R² = 0.678), but no relationship was found between L.A/S.A of otolith and fish weight. This strong relationship between fish weight and otolith length and diameter of T. ilisha, reflects that otolith length and diameter could become the best predictor of fish weight.