Vertical variability of wild fish assemblages around sea-cage fish farms: implications for management

AbstractThis study aims to determine the relationship between physico-chemical variables on a seasonal basis and wild fish assemblages beneath sea-cage fish farms. Assemblages of wild fish were counted monthly on two separate days at each of six fish farms between August 2015 and July 2017, by six rapid visual counts (RVC) in 5 minutes with scuba by two divers. Seawater samples were simultaneously taken by a Nansen bottle during the RVC from the fish farm barge. SST (°C), salinity (ppm), dissolved oxygen (mg l−1) and pH were measured by YSI multiparameter, while Secchi disk was also used for light transmittance. Wild fish species richness went up with increasing temperature and salinity in the Izmir region, however, this stopped at about 26°C and about 39 ppm. Wild fish richness increased when the DO was at a level of 7 mg l−1 and the pH at about 7.9 in Izmir. Between 10 and 20 m, light transmittance showed greater wild fish species richness in Izmir region. In contrast, the wild fish species richness of the Muğla region fluctuated more. In terms of wild fish species richness, these fluctuations increased with salinity and DO, while they decreased with SST, pH and light transmittance. However, the range of variation of the recorded physico-chemical variables is rather narrow. The results of the correlation matrix indicate that the relationship between wild fish species richness and pH and SST was statistically significant in Izmir region (P < 0.05).

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Seasonal variations in wild fish aggregation near sea-cage fish farms in the Turkish Aegean Sea

Aquaculture Reports ◽

10.1016/j.aqrep.2020.100478 ◽

2020 ◽

Vol 18 ◽

pp. 100478

Author(s):

Okan Akyol ◽

Aytaç Özgül ◽

F. Ozan Düzbastılar ◽

Halil Şen ◽

José M. Ortiz de Urbina ◽

...

Keyword(s):

Seasonal Variations ◽

Aegean Sea ◽

Wild Fish ◽

Fish Farms ◽

Fish Aggregation ◽

Sea Cage ◽

Cage Fish

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Seasonal patterns and diets of wild fish assemblages associated with Mediterranean coastal fish farms

ICES Journal of Marine Science ◽

10.1093/icesjms/fsn091 ◽

2008 ◽

Vol 65 (7) ◽

pp. 1153-1160 ◽

Cited By ~ 65

Author(s):

Damian Fernandez-Jover ◽

Pablo Sanchez-Jerez ◽

Just Tomás Bayle-Sempere ◽

Carlos Valle ◽

Tim Dempster

Keyword(s):

Fish Assemblages ◽

Abundant Species ◽

Stomach Content Analysis ◽

Wild Fish ◽

Seasonal Patterns ◽

Fish Farms ◽

Coastal Fish ◽

Fish Stocks ◽

Floating Structures ◽

Cage Fish

Abstract Fernandez-Jover, D., Sanchez-Jerez, P., Bayle-Sempere, J. T., Valle, C., and Dempster, T. 2008. Seasonal patterns and diets of wild fish assemblages associated with Mediterranean coastal fish farms. – ICES Journal of Marine Science, 65: 1153–1160. Fish are attracted to floating structures, including coastal cage fish farms, sometimes in dense aggregations. To understand better the influence of aquaculture on wild fish stocks, we carried out seasonal visual censuses around three southwestern Mediterranean farms over 2 years to assess the temporal patterns of the aggregated fish assemblage. In addition, we analysed the diet of the five most abundant species. Aggregations around all farms were large throughout the year, although species composition and abundance differed among farms and seasons. Fish farms are attractive habitats for certain species of wild fish in specific seasons. Adult fish of reproductive size dominated the assemblages, and stomach content analysis revealed that 66–89% of fish of the five most abundant taxa had consumed food pellets lost from the cages. We estimated that wild fish consume up to 10% of the pellets used at farms, indicating that food is a key attractant. Regional monitoring of farm-associated wild fish assemblages could aid management of the interaction of aquaculture and wild fish resources, because changes in feeding behaviour may have consequences for fish populations and local fisheries.

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Temporal variability of wild fish assemblages associated with a sea-cage fish farm in the south-western Mediterranean Sea

Estuarine Coastal and Shelf Science ◽

10.1016/j.ecss.2006.10.019 ◽

2007 ◽

Vol 72 (1-2) ◽

pp. 299-307 ◽

Cited By ~ 45

Author(s):

Carlos Valle ◽

Just T. Bayle-Sempere ◽

Tim Dempster ◽

Pablo Sanchez-Jerez ◽

Francisca Giménez-Casalduero

Keyword(s):

Mediterranean Sea ◽

Temporal Variability ◽

Fish Assemblages ◽

Western Mediterranean ◽

Fish Farm ◽

Wild Fish ◽

The South ◽

Western Mediterranean Sea ◽

Sea Cage ◽

Cage Fish

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Extensive Aggregations of Wild Fish at Coastal Sea-Cage Fish Farms

Hydrobiologia ◽

10.1023/b:hydr.0000038870.13985.0f ◽

2004 ◽

Vol 525 (1-3) ◽

pp. 245-248 ◽

Cited By ~ 72

Author(s):

Tim Dempster ◽

Pablo Sanchez-Jerez ◽

Just Bayle- Sempere ◽

Michael Kingsford

Keyword(s):

Wild Fish ◽

Fish Farms ◽

Coastal Sea ◽

Sea Cage ◽

Cage Fish

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Attraction of wild fish to sea-cage fish farms in the south-western Mediterranean Sea: spatial and short-term temporal variability

Marine Ecology Progress Series ◽

10.3354/meps242237 ◽

2002 ◽

Vol 242 ◽

pp. 237-252 ◽

Cited By ~ 146

Author(s):

T Dempster ◽

P Sanchez-Jerez ◽

JT Bayle-Sempere ◽

F Giménez-Casalduero ◽

C Valle

Keyword(s):

Mediterranean Sea ◽

Temporal Variability ◽

Western Mediterranean ◽

Wild Fish ◽

The South ◽

Fish Farms ◽

Short Term ◽

Western Mediterranean Sea ◽

Sea Cage ◽

Cage Fish

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Wild fish diversity around the sea-cage fish farms in the Aegean Sea

Ege Journal of Fisheries and Aquatic Sciences ◽

10.12714/egejfas.2019.36.3.08 ◽

2019 ◽

Vol 36 (3) ◽

pp. 271-283

Author(s):

Okan Akyol ◽

Tevfik Ceyhan ◽

F. Ozan Düzbastılar ◽

Aytaç Özgül ◽

Halil Şen

Keyword(s):

Sparus Aurata ◽

Dicentrarchus Labrax ◽

Aegean Sea ◽

Wild Fish ◽

Fish Diversity ◽

Fish Farms ◽

The Mediterranean ◽

Fish Aggregation ◽

Sea Cage ◽

Cage Fish

Structures, floating on the surface of the ocean attract both juvenile and adult fishes in great numbers and diversity. Natural and artificial Fish Aggregation Devices (FADs) in open seas are widely recognised for their capacity to attract pelagic fishes. It can be assumed that floating sea-cages act as a kind of FAD. Even, fish aggregations beneath the sea-cages increase much more by the influence of feeding. In this study, aggregations of wild fish were counted around six sea-cage fish farms in both northern and southern Aegean Sea. Each fish farm cultivated Sparus aurata and Dicentrarchus labrax and the farms deployed between 720 m and 3 km far from the coast. Between July 2015 and July 2017, assemblages of wild fish were counted bimonthly on two separate days at each of these farms. The Rapid Visual Counts (RVC) in five minutes with SCUBA and covering 11250 m3 were performed for six times within each farm. A total of 40 species, belonging to 22 families were recorded at fish farms, with 3 families, Sparidae (7 species), Carangidae (6 species) and Mugilidae (4 species) being particularly abundant. The results of the study and other studies conducted in other parts of the Mediterranean were merged; it was found that a total of 99 fish species were listed around sea-cage fish farms in the Mediterranean Sea.

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Food composition of whiting Merlangius merlangus, captured around the sea-cage fish farms in Ordu, south-eastern Black Sea

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315419000626 ◽

2019 ◽

Vol 99 (7) ◽

pp. 1651-1659 ◽

Cited By ~ 1

Author(s):

Tuğçe Şensurat-Genç ◽

Okan Akyol ◽

Aytaç Özgül ◽

Uğur Özden

Keyword(s):

Black Sea ◽

Food Composition ◽

Control Site ◽

Fish Farms ◽

South Eastern ◽

First Choice ◽

Significant Difference ◽

Merlangius Merlangus ◽

Sea Cage ◽

Cage Fish

AbstractThe food composition of whiting, Merlangius merlangus, caught around the sea-cage fish farms off the coast of Perşembe, was analysed and compared with the diet of whiting from a control site off the coast of Fatsa (Ordu Province, south-eastern Black Sea). A total of 815 stomach samples were collected during the study, and of these, 195 (23.9%) were empty. According to the percentage of relative importance index (IRI%), pellet food (47.8%) and Annelida (25%) were the main prey groups of whiting in the sea-cage fish farms area, while unidentified teleost (85.3%) and Engraulis encrasicolus (8.2%) were dominant in the control site. The other prey groups in both areas were Crustaceans (Mysidae, Amphipoda, Upogebia sp.), Sprattus sprattus and Gobius spp. Seasonally, pellet food was the most consumed food in all seasons, but Mysidae was the first preference of whiting around the sea-cage fish farms in spring. In the control site, unidentified teleost was the first preference in all seasons, except winter, where E. encrasicolus was the first choice, followed by crustaceans and S. sprattus in winter. Bray–Curtis analysis shows that seasonally, there is no significant difference in the sea-cage fish farms, while there is significant difference in the control site, and two-dimensional nMDS of IRI% revealed a clear separation between both sites. SIMPER analysis revealed that the most contributing factors to the differences between seasons were pellet food in the sea-cage fish farms, and E. encrasicolus in the control site.

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