The moustached thryssa Thryssa mystax (Bloch and Schneider, 1801), is an important bycatch landed by trawl nets and mini purse seines at Ratnagiri in Maharashtra. Morphometric characters and length-weight relationship of the moustached thryssa were studied from 876 specimens comprising of 436 males, 407 females and 33 indeterminates, collected from Ratnagiri. The coefficient of correlation of total length against other morphometric characters of T. mystax ranged between 0.3967 (against pre-pelvic length) to 0.9966 (against fork length). All morphometric measures had a high and moderate degree of correlation with total length. The length-weight relationship indicated isometric growth. The coefficient of correlation (r) for the length-weight relationship was estimated at 0.9327, 0.9266, 0.9743 and 0.9379 for the males, females, indeterminants and pooled data, respectively.

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Background The present study assessed the growth and mortality parameters of the white sardine, Escualosa thoracata which is having high local demand. The white sardine gained importance due to its taste, and high demand in domestic markets as compared to the oil sardine necessitated a study on this resource to know the present status of exploitation level along the central west coast of India. Results A total of 3026 individuals of different size groups of E. thoracata were randomly collected from the Burondi fish landing center of the Ratnagiri district of Maharashtra. The asymptotic length (L∞) and growth coefficient (K) were estimated to be 115 mm and 1.9 year−1, respectively, by ELEFAN-I and 135 mm and 1.2 year−1 by the scattergram. The value of t0 by von Bertalanffy plot was estimated to be −0.000012 year. The fish attained a length of 65 mm, 94 mm, and 114 mm at the end of 0.5, 1, and 1.5 years of its life, respectively. The instantaneous rate of total mortality (Z), natural mortality (M), and fishing mortality (F) were estimated to be 8.07 year−1, 2.55 year−1, and 5.52 year−1, respectively. The exploitation rate (U) was calculated as 0.65, and the exploitation ratio (E) was 0.68. Conclusion The growth, mortality, and other population parameters observed in the present study will help to understand the current stock status, which is pointing toward the over-fishing condition (E ˃ 0.50) of the white sardine in the study area. Therefore, the present investigation suggests reducing the fishing pressure on E. thoracata along the central west coast of India for the sustainability of the resource.