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Coastal Fish Farms as Fish Aggregation Devices (FADs)

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... Marine finfish species rearing in sea-cages has firstly been capacity to attract pelagic fishes ( Hunter and Mitchell 1967 ;Deudero 2001 ). Sea-cages fish farms may be analogous to large FADs and the floating cages provide structure in the pelagic environment, although the unused portion of feed that falls through the cages probably enhances the attraction effect ( Bjordal and Skar 1992 ;Dempster et al. 2002 ;Sanchez-Jerez et al. 2011 ). The phenomenon is widespread, and the large aggregations of wild fish have been well-known around the sea-cage fish farms throughout the Mediterranean, including Spain ( Dempster et al. 20 02 , 20 04 , 20 05 ;Valle et al. 2007 ;Fernandez-Jover et al. 2008 ;Arechavala-Lopez et al. 2011 ;Bacher et al. 2012 ), Greece ( Machias et al.,20 04 ;20 05 ), Adriatic ( Segvic Bubic et al. 2011 ) and Turkey ( Akyol and Ertosluk 2010 ;Akyol et al. 2020a , b) as well as the Canaries ( Boyra et al. 2004 ;Tuya et al. 2005 ). ...
... Pelagic A. boyeri, the typical FADassociated fish, have smaller sizes than carangids and clupeids. Sea-cages can act as conventional FADs by attracting wild fish, and FAD-associated fish are usually smaller ( < 15 cm) in the Mediterranean ( Dempster et al. 2002 ;Sanchez-Jerez et al. 2011 ). As mentioned above that the farm-aggregated wild fish consume large quantities of pellets lost from cages ( Dempster et al. 2002 ;Fernandez-Jover et al. 2008 ). ...
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Sea-cage fish farms cause wild fish to aggregate nearby. Nevertheless, it is still not clear to what extent the attraction effect around sea-cage fish farms varies according to the type and size of the reared species. We examined this attraction effect in six sea-cage fish farms across the Aegean Sea using an integrated approach combining these variables with seasonal and spatial factors. Six 5-minute rapid visual counts were conducted on each farm complex for comparing the wild fish aggregations around the sea-cages concerning both cultivated species (seabass and seabream) and their sizes (adult and juvenile). We counted a total of 509,061 fishes, representing 36 species and 18 families. While 292,377 fish belonging to 34 species were counted in seabass cages, 216,684 fish belonging to 27 species were counted at seabream cages. In addition, 160,192 fish belonging to 28 species were counted around the juvenile cages, while 348,869 fish belonging to 34 species were counted at adult fish cages. The study shows that wild fish communities are formed around the sea-cages where seabass and seabream are reared in both adult and juvenile sizes in the Aegean Sea. According to our results, the fish species reared in the cages do not have a statistically significant effect on the wild fish community structure around the cages, whereas fish size, which was correlated with cage biomass and a longer history of feeding, had a strong effect. Other factors affecting the wild fish community structure around the cages are the season and the location of the cages.
... The performance of cage fish farms as fish aggregation devices (FAD) is well known in the marine environment (Dempster et al., 2002;Sanchez-Jerez et al., 2011) and is mainly related to the availability of excess feed (Tuya et al., 2006). This same attractive effect of fish farms is reported in several studies in freshwater (Boyra et al., 2004;Brandão et al., 2012;Demétrio et al., 2012;Díaz López, 2017;Nobile et al., 2018), indicating that cage fish farms in inland waters can also act as a FAD. ...
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Cage fish farming in hydroelectric reservoirs has been reported to promote variations in environmental conditions, which directly interfere with the foraging behavior of wild fish. We have hypothesized that the abundance of foods derived from fish farming activities alters the interspecific relationships of wild fish. To test this, we evaluated the diet composition, trophic niche breadth, and trophic niche overlap of the wild fish fauna sampled in two areas (cage farm and control area). Changes in diet composition between areas were observed, resulting in contraction of the trophic niche, and partitioning of food resources in the cage farm area. These results indicate the complexity of the influence of cage fish farms and demonstrate the importance of studies on the wild fish fauna under the influence of these systems. Furthermore, the species evaluated here have economic potential for local fishing, and our results suggest the maintenance of fish stocks in the short term due to the energy supply of the cages.
... For example, a population dynamics and genetics model developed to support the hatchery reform process in the Pacific Northwest of the USA (Mobrand et al. 2005, Mobrand, Jones, andStokes 2006) has been modified to serve as a tool for genetic risk assessment of escapes from offshore aquaculture (Volk et al. 2015). Likewise, artificial reef science has provided a framework for understanding and managing the ecological and fisheries impacts of attraction of wild fish to offshore cages (Sanchez-Jerez et al. 2011). To facilitate such cross-fertilization and cross-discovery of knowledge, we draw attention to the many different terminologies and communities of practice involved in fisheries enhancement and related research. ...
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Fisheries enhancements are management approaches involving the use of aquaculture and habitat technologies (in the broadest sense) to enhance or restore fisheries. The technologies most commonly used include hatchery rearing and release of aquatic animals and provision of artificial structures such as artificial reefs. Both are associated with distinct fields of knowledge and communities of practice. Recent calls to expand and broaden the role of aquaculture and habitat enhancements in marine conservation and an increasingly integrated view of living marine resource management have led to an aspirational broadening of concepts in this area. The 10th William R and Lenore Mote Symposium and 6th International Symposium on Stock Enhancement and Sea Ranching aimed to advance and integrate knowledge across enhancement technologies and practices. Substantial progress was noted in multiple technical areas such as understanding the potential and limitations for rearing organisms fit for release into the wild, and the design of artificial reefs to enhance local fish abundance. Crucial higher-level goals such as effectively enhancing or restoring fish abundance and fisheries at the stock level continue to receive insufficient attention across the enhancement sciences. Integration of enhancement strategies provides opportunities and challenges including a need to recognize, cross-discover, and engage other distinct areas of knowledge and communities of practice. A quick reference guide is provided to facilitate this process.
... Aquaculture is a growing industry throughout many areas of the world (Duarte et al., 2009), with a reported 54.1 million tonnes (t) of finfish farmed in marine and coastal waters in 2016 . The benefits of providing added food security through fish proteins also assists to reduce the pressure of over-harvesting wild fisheries (Tidwell and Allan, 2001), however, these correspond with increasing fish aggregations in the local vicinity from the artificial structure and artificial pellets wastage from unconsumed food (Sanchez-Jerez et al., 2011). In Israel, 100 km 2 of marine space has been allocated for potential offshore development (Ayalon et al., 2015). ...
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