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Feeding ecology of little tunny Euthynnus alletteratus in the central Mediterranean Sea

Published online by Cambridge University Press:  30 July 2007

Manuela Falautano
Affiliation:
ICRAM, Central Institute for Marine Research, via E. Amari 124, 90139 Palermo, Italy
Luca Castriota
Affiliation:
ICRAM, Central Institute for Marine Research, via E. Amari 124, 90139 Palermo, Italy
Maria Grazia Finoia
Affiliation:
ICRAM, via di Casalotti 300, 00166 Roma, Italy
Franco Andaloro
Affiliation:
ICRAM, Central Institute for Marine Research, via E. Amari 124, 90139 Palermo, Italy

Abstract

The feeding habits of Euthynnus alletteratus and its variations compared to predator size in the central Mediterranean Sea were investigated. The stomach contents of 187 specimens were analysed, ranging from 26.8 to 50.3 cm total length, caught by authorized experimental drift-nets. The difference in food items found in the stomachs was evaluated by occurrence of prey frequency, prey weight, and prey abundance; these criteria were used to calculate an index of relative importance. Fish were the dominant food detected according to all numerical indicators examined and were mainly represented by Maurolicus muelleri and larval stages of teleosts. Hyperiid amphipods, dominated by Anchylomera blossevillei and Phrosina semilunata, were well represented in terms of frequency of occurrence. Variations in the diet composition compared to fish size were observed. Comparative analysis performed on prey abundance highlighted a trend of increasing predator size-classes among prey items. The specimens of the smallest sizes ate mainly adult clupeiforms and larvae or other juvenile teleosts. As fish grew, there were increased amounts of adult teleosts, crustaceans (hyperiids and isopods) and cephalopods. Maurolicus muelleri was the most important prey for the largest specimens analysed. Significant differences among size-classes, both in prey abundance and in prey weight, were confirmed by non-parametric multivariate analysis of variance (NP-MANOVA).

Type
Research Article
Copyright
2007 Marine Biological Association of the United Kingdom

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