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Subject: Fisheries Resource Management × Author: PRAMOD SUVARNA × End date: 2020 × Type: Thesis × Thesis Type: M.F.Sc ×
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    ThesisItemOpen Access
    “STUDIES ON REPRODUCTIVE BIOLOGY OF SPINELESS CUTTLEFISH SEPIELLA INERMIS”
    (KARNATAKA VETERINARY, ANIMAL AND FISHERIES SCIENCES UNIVERSITY, BIDAR, 2019) PRAMOD SUVARNA; S.R.SOMASHEKAR
    Sepiella inermis, also known as the spineless cuttlefish, is an emerging species in the cuttlefish fishery. This species has been attracting international market in the recent years. The present study was undertaken to investigate the reproductive biology of S. inermis off Mangaluru, south-west coast of India. The S. inermis samples were collected from Mangaluru Fisheries Harbour during September 2016 and May 2017. The relationship between dorsal mantle length (DML) and body weight (TW) of Sepiella inermis was mathematically expressed as TW= 0.9873×DML2.0828 (r² = 0.8683) and TW = 0.9725×DML2.1789(r² = 0.8622) for male and female respectively. The species showed allometric growth. Maturity stages were assigned by gross macroscopic examination of the gonad as 1) immature, 2) maturing 3) mature and 4) spent. Apparently, female tend to gain more weight than male for a given length. The female: male ratio ranged between 0.90:1 (September) to 1:1 (April). 50% of the male matured at 50-55 mm and female matured at 60-65 mm. Fecundity varied from 172 to 560. Ova diameter varied between 0.29 to 6.12 mm, individuals in all the 4 maturity stages were found throughout the year. However, maximum proportion of matured male and female were encountered during September-October followed by February-April. Furthermore, the highest Gonadosomatic Index (GSI) for male and female also coincided with spawning season. Nidamental gland Index (NGI) peaked in the month of October. Based on the proportion of each maturity stage, as well as the maturity indices (GSI and NGI), the spawning seasons were inferred to be in the months of October-September and February-April