J. Bio. Env. Sci.12(3), 192-200, March 2018
The diet of blue shark, Prionace glauca (Linnaeus, 1758), off the coastal waters of Ivory Coast (west Africa) was studied according to sexes, maturity groups and hydrological seasons from August 2014 to November 2016. Stomach contents of 262 specimens ranging from 195 to 320 cm total length caught by artisanal driftnet fishery were analysed. Of the stomach contents examined, 94 were empty (36%). The large number of empty stomachs may be the result of using hooks, which cause high stress resulting in regurgitation. Diet was described using the Index of Relative Importance (% IRI) combining occurrence, numerical and weight percentages. The overall diet consisted of cephalopods, teleost fishes, cartilaginous fishes, crustaceans and mammals of which cephalopods (84.2%) represented by Haliphron atlanticus (27.7%), Histioteuthis macrohista (22.0%) and Abraliopsis gilchristi (9.8%) were the main preys. The diet did not vary greatly according sexes, maturity groups and seasons. The Morisita-Horn index and the Spearman rank correlation coefficient showed similarity of diet between sexes (Cλ = 0.70, Rs = 0.41, p = 0.0035), maturity groups (Cλ = 0.49, Rs = 0.73, p = 0.00002) and seasons (Cλ = 0.62, Rs = 0.58, p = 0.004) in this area. The low trophic niche breadth associate to a large prey trophic spectrum found in this study indicate that blue shark is an opportunist predator.
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