Journal of the Marine Biological Association of the United Kingdom



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


Manuela  Falautano a1c1, Luca  Castriota a1, Maria Grazia  Finoia a2 and Franco  Andaloro a1
a1 ICRAM, Central Institute for Marine Research, via E. Amari 124, 90139 Palermo, Italy
a2 ICRAM, via di Casalotti 300, 00166 Roma, Italy

Article author query
falautano m   [PubMed][Google Scholar] 
castriota l   [PubMed][Google Scholar] 
finoia mg   [PubMed][Google Scholar] 
andaloro   [PubMed][Google Scholar] 

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).

(Published Online July 30 2007)
(Received September 19 2006)
(Accepted May 16 2007)


Correspondence:
c1 Corresponding author, e-mail: mfalau@tin.it