Search

The population of meagre ( Argyrosomus regius) has increased dramatically around the Western Mediterranean, accompanied by a higher seasonal incidence of the species in fishery landings. Presumably because of escapes, this new predator is gaining ground in marine habitats where it was normally not found. Given the lack of knowledge about the potential impact of this locally absent species on ecosystems and fishery resources, the objective of this study was to analyse the diet and predation behaviour of A. regius in order to evaluate its capability to adapt to a new environment as well as to identify its main prey. Stomach contents of 159 individuals were analysed and the identifiable prey items classified into major groups. Results showed that the diet of meagre was remarkably size-dependent. The commercially important decapod Melicertus kerathurus (Index of Relative Importance IRI: 798.53), and to a lesser extent other crustaceans, were preferred to smaller sizes, while larger individuals gradually shifted to a piscivorous diet, particularly to Platichthys flesus (77.99 IRI). The potential ecological effects on the prey species are discussed, and management measures preventing the establishment of new local populations are suggested in order to harmonize coastal zone management policies with a sustainable production of meagre. [ABSTRACT FROM AUTHOR]

The article presents a study which offers evidence of whether sea bass escapees are short- or long-lived and to assess the feeding habits of externally-tagged sea bass recaptured by local fishermen in the Mediterranean Sea. The application of the tagging method in which the fishermen were provided with the fish information is cited. It is inferred that the presence of particulate organic matters in the stomachs indicate the aggressive feeding behaviour of escaped sea bass.

The present study compares fin damages in gilthead seabream ( Sparus aurata) and European seabass ( Dicentrarchus labrax) according to their wild, escaped or farmed origins. In addition, the potential applicability of fin condition indices (Fin Erosion Index ' FEI' and Fin Splitting Index ' FSI') as identification tools is discussed. Farmed seabream fins evidenced more erosion and splitting ( FEI ± SD: 2.1 ± 0.3; FSI ± SD: 1.9 ± 0.6) than wild seabream fins ( FEI: 0.8 ± 0.6; FSI: 1.2 ± 0.9), a result of farming conditions in open-sea cages. Escaped seabream fin erosion was between that of farmed and wild seabream ( FEI: 1.6 ± 0.4), which could indicate that fins in farmed fish recover over time from farming abrasions once they are in the wild. However, the fins of escaped seabream seem to be weaker than those of the wild fish, and therefore might be more susceptible to suffer other types of erosion such as splitting or nipping ( FSI: 2.3 ± 0.7). No significant differences were found in seabass FEI according to their origins, although wild seabass presented significantly more split caudal fins ( FSI: 3.3 ± 2.8) than the farmed seabass ( FSI: 1.2 ± 1.1) and escapees ( FSI: 2.5 ± 1.6). Therefore, FEI for seabream could be used as tools not only to distinguish between wild and farmed fish, but also to identify recent escapees, improving further assessments on the contribution of seabream escapees in fishery landings. However, the healing potential of damaged fins must be considered for the proper identification of escapees. Use of fin condition indices from both species could be helpful for aquaculture management, to assess fish welfare in fish farms stocks, and improve the knowledge of handling, stock densities and open-sea cage environment conditions. [ABSTRACT FROM AUTHOR]