Fish Farms at Sea: The Ground Truth from Google Earth
Pablo Trujillo*, Chiara Piroddi, Jennifer Jacquet
Fisheries Centre, University of British Columbia, Vancouver, British Columbia, Canada
In the face of global overfishing of wild-caught seafood, ocean fish farming has augmented the supply of fresh fish to western markets and become one of the fastest growing global industries.
Due to extensive and expanding overfishing of wild-caught seafood [3,4], ocean fish farming has grown to augment the supply of fresh fish to western markets. Indeed, it is one of the fastest growing global industries . The accuracy of available data for farmed fish is important to gauge the magnitude and growth of this industry, its role in feeding global seafood demand, and also for determining the industry’s impact on small pelagic fish because farmed fish currently require large quantities of wild fish for fishmeal and oil .
Ocean fish farming began in the Mediterranean in the early 1980s and is now widespread. Stationary cages speckle the coasts of 16 Mediterranean countries and are visible from satellite imagery available through Google Earth (Figure 1) which we used to estimate the farmed fish production in the Mediterranean Sea, which we compare to data on farmed fish production provided by each Mediterranean country provided to the FAO, the organization mandated to collect data for capture fisheries and farmed fish production, in 2006.
Of the entire Mediterranean coast, Google Earth satellite images were available for 91% of the Mediterranean shores. We identified and counted 248 tuna cages (circular cages > 40 m diameter  and 20,976 other fish cages (Figure 1) within 10 km offshore, the majority of which were off Greece (49%) and Turkey (31%). Around 80% of cages are located within 1 km of shore (Table 1).
Table 1: Number of cages, closest and furthest cage to shore, average area per cage, and the various assumptions used to estimate finfish production for each Mediterranean country. We provide three different estimates of finfish production based on different assumptions about the percentage of cages (50, 75, 100) that are fully operational. The final column provides the reported finfish production to FAO in 2006 by country.
[Download the full paper here]
References (numbering follows the original paper)
3. Roberts, C.M. 2002. Deep impact: the rising toll of fishing in the deep sea. Trends in Ecology & Evolution 17: 242–245.
4. Swartz, W., Sala, E., Tracey, S., Watson, R. & Pauly, D. 2010 The spatial expansion and ecological footprint of fisheries (1950 to present). PloS one 5:e15143.
5. Duarte, C.M., Holmer, M., Olsen ,Y., Soto, D. & Marbà N. 2009. Will the oceans help feed humanity? BioScience 59: 967-976.
6. Naylor, R.L., Goldburg, R.J., Primavera, J,H., Kautsky, N., Beveridge, M.C.M. 2000. Effect of aquaculture on world fish supplies. Nature 405: 1017–1024.
11. Halwart M, Soto D, Arthur JR (2007) Cage aquaculture: regional reviews and global overview: Food and Agriculture Organization of the United Nations.
16. Golomazou, E., Athanassopoulou, F., Vagianou, S., Sabatakou ,O. & Tsantilas, H. 2006. Diseases of white sea bream (Diplodus sargus L.) reared in experimental and commercial conditions in Greece. Turkish Journal of Veterinary and Animal Sciences 30: 389.
17. Machias, A., Giannoulaki, M., Somarakis, S., Maravelias, C. & Neofitou, C. 2006. Fish farming effects on local fisheries landings in oligotrophic seas. Aquaculture 261: 809–816.
18. FAO. 2010. The State of the world fisheries and aquaculture Rome. 197 pp.
20. Kilic, H. 1999. Site selection. The case of Turkey. Option Mediterraneennes -International Centre for Advanced Mediterranean Agronomic Studies. pp 25–33.
21. Sahin, M. 1996. Seabass and Bream in Floating Cages in Turkey. Option Mediterraneennes - International Centre for Advanced Mediterranean Agronomic Studies. pp 57–63.
22. Costanzo, M., Maricchiolo, G, Arigo`, K. & Genovese L. 2006. L’acquacoltura nella provincia di Messina. 50 pp.
23. Šarušić ,G. 2000. Mariculture on Croatian islands. Ribarstvo 58: 111–118.
24. Molina Dominguez, L., Lopez Calero, G., Vergara Martı´n J. & Robaina Robaina, L. 2001. A comparative study of sediments under a marine cage farm at Gran Canaria Island (Spain). Preliminary results. Aquaculture 192: 225–231.
25. Basurco, B. & Larrazabal, G. 2000. Marine fish farming in Spain. Option Mediterraneennes - International Centre for Advanced Mediterranean Agronomic Studies. pp 45–56.
26. Stephanou, D. 2002. Country report: Cyprus. Option Mediterraneennes -International Centre for Advanced Mediterranean Agronomic Studies. pp 35–40.