REPRODUCTIVE BIOLOGY OF Liza tade FROM THE SOUTHEAST COAST OF BANGLADESH: INSIGHTS FROM GONADOSOMATIC INDEX AND GONADAL HISTOLOGY

Abstract

This study examined the reproductive biology of Liza tade, commonly known as the thin-lipped mullet, in the southeast coastal region of Bangladesh. A total of 979 specimens (467 males and 512 females) were collected from the Chowfaldandi Bridge area of the Maheshkhali channel, Cox’s Bazar, between February 2023 and January 2024. The specimens ranged in total length from 9 to 18.7 cm and in body weight from 11.68 to 63.53 g. The overall sex ratio (male:female = 0.91:1) did not significantly deviate from the expected 1:1 ratio. Length-weight relationships (LWR) revealed negative allometric growth (b < 3) for both sexes, with growth coefficients of 2.098 for males and 2.172 for females and R² values of 0.717 and 0.723, respectively. The relative condition factor (KR) for males ranged from 0.57 to 1.83, and for females from 0.30 to 1.60, while Fulton’s condition factor (KF) varied between 0.73 to 2.73 in males and 0.33 to 2.48 in females. The relative weight (WR) of both sexes showed no significant deviation from 100, suggesting that the species' habitat remains in favourable condition. Sexual maturity was reached at 10.8 cm in males and 11.1 cm in females, with the mean gonado-somatic index (GSI) for females peaking in December and reaching its lowest in June. The highest recorded individual fecundity was 61248 ± 7560 eggs in December. Histological analysis of ovaries showed 80% mature oocytes at various developmental stages in December, indicating peak reproductive activity. Based on GSI, fecundity, and gonadal histology, the breeding season of L. tade extends from November to February. These findings offer valuable insights for enhancing induced breeding practices and for the sustainable management of L. tade populations in this region.