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Subject: Fisheries Resource Management × Author: BHAVANJALI M.R × End date: 2019 × Start date: 2017 × Thesis Type: M.F.Sc ×
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    ThesisItemOpen Access
    TROPHIC INTERACTION IN COMMERCIALLY EXPLOITED DEMERSAL FINFISHES WITH EMPHASIS ON ONTOGENIC DIET SHIFTS
    (KARNATAKA VETERINARY, ANIMAL AND FISHERIES SCIENCES UNIVERSITY, BIDAR, 2018) BHAVANJALI M.R; MRIDULA RAJESH
    Trophic interactions in seven commercially exploited marine demersal finfishes of Karnataka were studied to understand the trophic organization with an emphasis on ontogenic diet shifts and trophic overlap. In total, 4723 stomachs were examined of which 73 prey items were identified. Crustaceans and fishes formed the major prey item. Based on cluster analysis of predator feeding similarities and ontogenic diet shift within each predator, two major trophic guilds were identified. The first guild of ‘crustacean feeders’ included all size groups of Nemipterus japonicus, N. randalli, O. cuvieri and Priacanthus hamrur. The second trophic guild, ‘piscivores’, was mainly made up of larger size groups of all predators and all size groups of Saurida tumbil and S. undosquamis. The mean diet breadth and mean trophic level showed a strong correlation with ontogenic diet shift. TROPH values ranged from 3.4-4.6 for species indicating carnivorous diet pattern of the species. All the species were carnivores and the extent of carnivory increased with ontogeny. It is clear from the present study that most of the species when they were young preferred crustaceans, other invertebrates and smaller fishes but the preference changed for teleosts and other carnivores as they grew in size and age. A seasonal variation in the diet pattern observed was due to variations in prey abundance. Trophic network analysis showed maximum prey in Trophic level III and any alterations due to ecological or anthropogenic activities affecting the prey would result in alterations in community dynamics of the predators.