Ecological role of bluefin tuna (Thunnus thynnus) fish farms for associated wild fish assemblages in the Mediterranean Sea

Morphological and ecophysiological adaptations of wild gilthead seabream Sparus aurata associated with tuna farms

“…It seems that the observed farms share similar environmental conditions, primarily in terms of trophic resources, which are re sponsible for triggering similar morphological adaptive responses in FA populations. Tuna farms are highly attractive habitats for surrounding wild fish whose aggregations of juvenile and adult stages persist year-round in large numbers, including gilthead seabreams (Šegvić-Bubić et al 2011c, Stagličić et al 2017. In addition to the fact that sea cages at fish farms add structure to the water column, analogous to large fish attraction devices (Dempster et al 2011, the attraction of fish is also driven by large amounts of feed available at fish farms (Tuya et al 2006, Fernandez-Jover et al 2008.…”

“…The allocation of surplus energy to male functions beyond a certain point carries little reproductive return, since females have grown to a size at which they have sufficient reproductive success even at lower length classes. Furthermore, observed increased population density of gilthead seabream in farm-impacted areas (Šegvić-Bubić et al 2011c, Stagličić et al 2017) could also have further fostered sex change, since gender transition in hermaphrodites can occur in concert with changes in particular social/mating systems, habitat and population density (Munday et al 2006, Avise 2011, Erisman et al 2013. Thus, the plasticity of gonadal development and sex allocation, as a function of size/age, can be altered by the habitat and behavioural conditions in which gilthead seabream populations dwell.…”

“…The attraction effect of fish farms on wild fish populations (Dempster et al 2005, Šegvić-Bubić et al 2011c, Stagličić et al 2017 and the ecological and genetic impacts of escapees on wild counterparts (Rogdakis et al 2011, Šegvić-Bubić et al 2011a, Arechavala-Lopez et al 2013, Toledo-Guedes et al 2014a have been widely studied and provide the basis for recommendations to manage escape scenarios (Are cha vala-Lopez et al 2013, 2018a,b, Dempster et al 2018. External characteristics (e.g.…”

“…Research on the ecological impacts of inshore and coastal finfish farms on the surrounding environment and biota is well documented, whereas there is limited information for semi-offshore locations where tuna are farmed. Differences in the surrounding wild fish assemblages around tuna and other finfish farms are mainly associated with the type of feed used and the environmental conditions at the locations of these facilities (Šegvić-Bubić et al 2011c, Stagličić et al 2017. Tuna farms require excessive quantities of feed in the form of fresh or defrosted baitfish, which greatly differ from pellets that are used at seabream and seabass farms, in terms of proximate composition, leachability, dimensions and settling velocities (Vita et al 2004, Aguado-Giménez & García-García 2005, Vassallo et al 2006, Fernandes et al 2007, Šegvić-Bubić et al 2011c, forming high-quality habitats that enhance the fitness of coastal fish assemblages (Stagličić et al 2017).…”

“…The Sparidae are one of the most abundant families found year-round in wild fish assemblages aggregating around tuna sea cages in Croatia (Šegvić-Bubić et al 2011c, Stagličić et al 2017. They are also exploited and farmed commercially for human consumption, and fished recreationally (Basurco et al 2011).…”