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Deciphering the Dynamics of Reproduction and Diet for Bigeye Ilisha (Ilisha megaloptera) from the Saurashtra Coast, Northeastern Arabian Sea

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Relation http://eprints.cmfri.org.in/16311/
https://bioone.org/journals/journal-of-coastal-research/volume-38/issue-5/JCOASTRES-D-22-00007.1/Deciphering-the-Dynamics-of-Reproduction-and-Diet-for-Bigeye-Ilisha/10.2112/JCOASTRES-D-22-00007.1.short
https://doi.org/10.2112/JCOASTRES-D-22-00007.1
 
Title Deciphering the Dynamics of Reproduction and Diet for Bigeye Ilisha (Ilisha megaloptera) from the Saurashtra Coast, Northeastern Arabian Sea
 
Creator Ghosh, Shubhadeep
Vase, Vinay Kumar
 
Subject Tropical fish
Fish breeding
Food and Feeding
 
Description With no exhaustive information available for Ilisha megaloptera, the present study aimed at elucidating the
reproductive and feeding dynamics from 764 individuals landed by gillnetters at Veraval, India, in the northeastern
Arabian Sea. Standard length ranged from 18.4 cm to 35.2 cm. Growth was isometric in males and negatively
allometric in females. Sex ratio (F:M) was 1.22, with significant dominance of females at most size classes. Maturity
sizes for females and males were 24.21 cm and 24.92 cm. Observation showed that Ilisha megaloptera spawned
throughout the year with major and minor peaks occurring from February to May and November to December,
respectively. The monthly percentage contribution of spawning females and males ranged from 16.0 to 72.22 and 22.22
to 73.68, and the gonadosomatic index for females varied between 3.59 and 7.68. Absolute fecundity ranged from
22,875 eggs to 121,013 eggs. Asynchronous ovarian development with three distinct modes in egg distribution
indicated multiple spawning events. Feeding intensity was low, with 26.05% exhibiting part-full stomachs and 7.20%
full stomachs. Feeding activity was lowest during spawning peaks and highest in fishes measuring 26.0–29.9 cm.
Below 22.0 cm, feeding was solely on zooplankton, dominated by copepods. Feeding henceforth was mostly on nekton:
crustaceans (39.35%) and teleost juveniles (38.72%). Ontogenetic shifts and seasonal variations in prey signified
optimal foraging. Precipitation and salinity significantly impacted the monthly gonadosomatic index and predator–
prey weight ratio. The present study provides a detailed report on bionomics for Ilisha megaloptera and could
contribute to the management of Ilisha spp. stocks in the Indian Ocean, considering the paucity of information
available for other species in this genus.
 
Publisher BioOne
 
Date 2022
 
Type Article
PeerReviewed
 
Format text
 
Language en
 
Identifier http://eprints.cmfri.org.in/16311/1/JCR_2022_Shubhadeep%20Ghosh.pdf
Ghosh, Shubhadeep and Vase, Vinay Kumar (2022) Deciphering the Dynamics of Reproduction and Diet for Bigeye Ilisha (Ilisha megaloptera) from the Saurashtra Coast, Northeastern Arabian Sea. Journal of Coastal Research, 38. pp. 1050-1060. ISSN 1551-5036