The use of trophic resources byArgyrosomus regius(Asso, 1801) escaped from Mediterranean offshore fish farms

Abstract

Summary 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.

Assessing the influence of gilthead sea bream escapees in landings of Mediterranean fisheries through a scale‐based methodology

“…2012c; Valero‐Rodríguez et al . ). This will guarantee the sustainability of other uses of the coastal zone.…”

“…Thus, a monitoring programme at landing ports and points of first sale should be implemented to start developing time series of data, and estimate population dynamics separately. In general, management of artisanal fisheries (Izquierdo-G omez & Sanchez-Jerez 2016) to avoid negative interactions of escapees with wild counterparts and/or other species is widely recommended (Toledo-Guedes et al 2009, 2014bArechavala-Lopez et al 2012c;Valero-Rodr ıguez et al 2015). This will guarantee the sustainability of other uses of the coastal zone.…”

“…2012c; Valero‐Rodríguez et al . ). Moreover, reared S. aurata may spawn while in sea cages releasing fertilised eggs to the water column, which together with escaped individuals may enhance the stock recruitment of the wild populations, and confuse the results of stock assessments (Somarakis et al .…”

“…Escape events are critical for the industry, especially for small facilities, which cannot cope with large losses of fish. There are also ecological implications arising from the presence of escapees in the wild, for example reduction of genetic diversity of wild conspecific populations through hybridisation ( Segvi c-Bubi c et al 2011b, 2014 and increased competition for food and habitat with other organisms (Toledo-Guedes et al 2009;Arechavala-Lopez et al 2012c;Valero-Rodr ıguez et al 2015). Moreover, reared S. aurata may spawn while in sea cages releasing fertilised eggs to the water column, which together with escaped individuals may enhance the stock recruitment of the wild populations, and confuse the results of stock assessments (Somarakis et al 2013) and/or depreciate the value of the species in the market (Dimitriou et al 2007).…”

Rapid dispersion of escaped meagre (Argyrosomus regius ) from a coastal Mediterranean fish farm

“…Spain, Turkey, Greece, Italy and France) (Jiménez, Pastor, Grau, Alconchel & Cárdenas ; El‐Shebly, El‐Kady, Hussin & Hossain ; Sadek, Sabry & Asfoor ; Monfort ). However, farmed meagre may escape from coastal floating net pens, interacting with the coastal environment and local fisheries (Dulčić, Bratulovic & Glamuzina ; Sanchez‐Jerez, Izquierdo‐Gomez, Arechavala‐Lopez, Bayle‐Sempere, Fernandez‐Jover, Valero‐Rodriguez & Dempster ; Arechavala‐Lopez, Valero‐Rodriguez, Peñalver‐García, Izquierdo‐Gomez & Sanchez‐Jerez ; Valero‐Rodriguez, Toledo‐Guedes, Arechavala‐Lopez, Izquierdo‐Gomez & Sanchez‐Jerez ). Escaped fish from sea cages represent a considerable economic loss for the farmers and is one of the main environmental problems in aquaculture, perceived as a threat to natural biodiversity in marine waters (Naylor, Hindar, Fleming, Goldburg, Williams, Volpe, Whoriskey, Eagle, Kelso & Mangel ).…”