Research Papers: Ocean Space Utilization

Flow Fields Inside Stocked Fish Cages and the Near Environment

[+] Author and Article Information
Lars C. Gansel

Norwegian University of Science
and Technology,
Trondheim 7010, Norway
e-mail: Lars.Gansel@sintef.no

Siri Rackebrandt

Carl v. Ossietzky University Oldenburg,
Oldenburg 26129, Germany
e-mail: Siri.Rackebrandt@uni-oldenburg.de

Frode Oppedal

Institute of Marine Research,
Matredal 5984, Norway
e-mail: FrodeO@imr.no

Thomas A. McClimans

SINTEF Fisheries and Aquaculture,
Trondheim 7010, Norway
e-mail: Thomas.A.McClimans@sintef.no

Contributed by the Ocean, Offshore, and Arctic Engineering Division of ASME for publication in the JOURNAL OF OFFSHORE MECHANICS AND ARCTIC ENGINEERING. Manuscript received July 7, 2011; final manuscript received May 20, 2014; published online June 12, 2014. Assoc. Editor: Hideyuki Suzuki.

J. Offshore Mech. Arct. Eng 136(3), 031201 (Jun 12, 2014) (8 pages) Paper No: OMAE-11-1059; doi: 10.1115/1.4027746 History: Received July 07, 2011; Revised May 20, 2014

This study explores the average flow field inside and around stocked Atlantic salmon (Salmo salar L.) fish cages. Laboratory tests and field measurements were conducted to study flow patterns around and through fish cages and the effect of fish on the water flow. Currents were measured around an empty and a stocked fish cage in a fjord to verify the results obtained from laboratory tests without fish and to study the effects of fish swimming in the cage. Fluorescein, a nontoxic, fluorescent dye, was released inside a stocked fish cage for visualization of three-dimensional flow patterns inside the cage. Atlantic salmon tend to form a torus shaped school and swim in a circular path, following the net during the daytime. Current measurements around an empty and a stocked fish cage show a strong influence of fish swimming in this circular pattern: while most of the oncoming water mass passes through the empty cage, significantly more water is pushed around the stocked fish cage. Dye experiments show that surface water inside stocked fish cages converges toward the center, where it sinks and spreads out of the cage at the depth of maximum biomass. In order to achieve a circular motion, fish must accelerate toward the center of the cage. This inward-directed force must be balanced by an outward force that pushes the water out of the cage, resulting in a low pressure area in the center of the rotational motion of the fish. Thus, water is pulled from above and below the fish swimming depth. Laboratory tests with empty cages agree well with field measurements around empty fish cages, and give a good starting point for further laboratory tests including the effect of fish-induced currents inside the cage to document the details of the flow patterns inside and adjacent to stocked fish cages. The results of such experiments can be used as benchmarks for numerical models to simulate the water flow in and around net pens, and model the oxygen supply and the spreading of wastes in the near wake of stocked fish farms.

Copyright © 2014 by ASME
Your Session has timed out. Please sign back in to continue.


Løland, G., 1991, “Current Force on and Flow Through Fish Farms,” Ph.D. thesis, Division of Marine Hydrodynamics, The Norwegian Institute of Technology, Trondheim, Norway.
Zhan, J. M., Jia, X. P., Li, Y. S., Sun, M. G., Guo, G. X., and Hu, Y. Z., 2006, “Analytical and Experimental Investigation of Drag on Nets of Fish Cages,” Aquacultural Eng., 35, pp. 91–101. [CrossRef]
Patursson, O., 2008, “Flow Through and Around Fish Farming Nets,” Ph.D. thesis, Ocean Engineering, University of New Hampshire, Durham, NH.
Patursson, Ø., Swift, R., Tsukrov, I., Simonsen, K., Baldwin, K., Fredriksson, D. W., and Celikkol, B., 2010, “Development of a Porous Media Model With Application to Flow Through and Around a Net Panel,” Ocean Eng., 37, pp. 314–324. [CrossRef]
Gansel, L. C., McClimans, T. A., and Myrhaug, D., 2012, “The Effects of Fish Cages on Ambient Currents,” ASME J. Offshore Mech. Arctic Eng.134(1), p. 011303. [CrossRef]
Gansel, L. C., McClimans, T. A., and Myrhaug, D., 2012, “Flow Around the Free Bottom of Fish Cages in a Uniform Flow With and Without Fouling,” J. Offshore Mech. Arctic Eng., 134(1), p. 011501. [CrossRef]
Gansel, L. C., McClimans, T. A., and Myrhaug, D., 2010, “Average Flow Inside and Around Fish Cages With and Without Fouling in a Uniform Flow,” 29th ASME International Conference on Offshore Mechanics and Arctic Engineering (OMAE 2010), Shanghai, China, June 6–11, Paper No. OMAE2010-20481. [CrossRef]
Harendza, A., Visscher, J., Gansel, L., and Pettersen, B., 2009, “PIV on Inclined Cylinder Shaped Fish Cages in a Current and the Resulting Flow Field,” 27th ASME International Conference on Offshore Mechanics and Arctic Engineering (OMAE2008), Estoril, Portugal, June 15–20, Paper No. OMAE2008-57746. [CrossRef]
Guenther, J., Misimi, E., and Sunde, L. M., 2010, “The Development of Biofouling, Particularly the Hydroid Ectopleura Larynx, on Commercial Salmon Cage Nets in Mid-Norway,” Aquaculture, 300, pp. 120–127. [CrossRef]
Lader, P., Dempster, T., Fredheim, A., and Jensen, Ø., 2008, “Current Induced Net Deformations in Full-Scale Cages for Atlantic Salmon (Salmo Salar),” Aquaculture Eng., 38, pp. 52–65. [CrossRef]
Moe, H., Fredheim, A., and Hopperstad, O. S., 2010, “Structural Analysis of Aquaculture Net Cages in Current,” J. Fluids Struct., 26, pp. 503–516. [CrossRef]
Johansson, D., Juell, J.-E., Oppedal, F., Stiansen, J.-E., and Ruohonen, K., 2007, “The Influence of the Pycnocline and Cage Resistance on Current Flow, Oxygen Flux and Swimming Behaviour of Atlantic Salmon (Salmo salar L.) in Production Cages,” Aquaculture, 265, pp. 271–287. [CrossRef]
Inoue, H., 1972, “On Water Exchange in a Net Cage Stocked With the Fish, Hamachi,” Bull. Jpn. Soc. Sci. Fish., 38, pp. 167–176 (in Japanese). [CrossRef]
Chacon-Torres, A., Ross, L. G., and Beveridge, M. C. M., 1988, “The Effects of Fish Behaviour on Dye Dispersion and Water Exchange in Small Net Cages,” Aquaculture, 73, pp. 283–293. [CrossRef]
Oppedal, F., Dempster, T., and Stien, L., 2011, “Environmental Drivers of Atlantic Salmon Behaviour in Sea-Cages: A Review,” Aquaculture, 311, pp. 3–18. [CrossRef]
Juell, J. E., 1995, “The Behavior of Atlantic Salmon in Relation to Efficient Cage-Rearing,” Rev. Fish. Biol. Fisher., 5, pp. 320–335. [CrossRef]
Bjordal, Å., Juell, J. E., Lindem, T., and Fernö, A., 1993, “Hydroacoustic Monitoring and Feeding Control in Cage Rearing of Atlantic Salmon (Salmo salar L.),” Fish Farming Technology, H.Reinertsen, L. A.Dahle, L.Jørgensen, and K.Tvinnereim, eds., Balkema, Rotterdam, pp. 203–208.
Oppedal, F., Juell, J. E., and Johansson, D., 2007, “Thermo- and Photoregulatory Swimming Behaviour of Caged Atlantic Salmon: Implications for Photoperiod Management and Fish Welfare,” Aquaculture, 265, pp. 70–81. [CrossRef]
Nilsen, A., Bjøru, B., Vigen, J., Oppedal, F., and Høy, E., 2010, “Evaluering av Metoder for Badebehandling mot lakselus i Stormerd,” Veterinærinstituttets rapportserie, 17-2010, Veterinærinstituttet, Oslo, Norwegian, p. 48.
Rackebrandt, S., 2008, “Water Flow in and Around Fish Cages,” Report to Marine Constructions, University of Science and Technology, Trondheim, Norway.


Grahic Jump Location
Fig. 1

Location of field experiments

Grahic Jump Location
Fig. 2

Setup of the experimental fish farm of the Institute of Marine Research in Matredal, north of Bergen, Norway. Dye experiments were conducted in cage 3.

Grahic Jump Location
Fig. 3

Dye spreading in cage 3 within the first 170 s at 14:57 (Oct. 31, 2009). The arrows indicate the flow direction and are obtained by tracking the movement of dye blobs between two pictures. The lowest plot is a combination of the arrow plots in the middle. The ambient flow speed was approximately 0.06 m/s.

Grahic Jump Location
Fig. 4

Dye spreading in cage 3 within 120 s at 15:10 (Oct. 31, 2009). See Fig. 4 for details. The ambient flow speed was approximately 0.09 m/s.

Grahic Jump Location
Fig. 5

Setup of the current measurements at the Solheim site. 3A shows the location of cage 5 in the fish farm setup and 3B shows cage 5 only. The dots mark the positions of 5 Nortek vector current meters.

Grahic Jump Location
Fig. 6

Variation of density with depth at Solheim on Aug. 22, 2008 and on Sept. 2, 2008. (Sigma-T is density minus 1000 kg/m3.)

Grahic Jump Location
Fig. 7

Vertical distribution of fish biomass from Sept. 2, 2008 to Sept. 5, 2008. Full day numbers mark midnight.

Grahic Jump Location
Fig. 8

Current direction and speed at five locations around cage 5 (see Fig. 3) at four different depths on Aug. 22, 2008 at 17:00. Figures (a)–(d) show the currents at 2 m, 4 m, 8 m, and 15 m, respectively. The length of the arrows indicates the current speed and the orientation of the arrows indicates the current direction. The black arrows are the results from the 5 current meters. The bold arrow in the lower left corner shows the ambient current.

Grahic Jump Location
Fig. 9

Same as Fig. 8, but for Aug. 23, 2008 at 07:00

Grahic Jump Location
Fig. 10

Same as Fig. 8, but d is for 10 m depth and e is for 12 m depth and for Sept. 2, 2008 at 17:00

Grahic Jump Location
Fig. 11

Same as Fig. 10, but for Sept. 4, 2008 at 12:00

Grahic Jump Location
Fig. 12

Same as Fig. 8, but for Sept. 2, 2008 at 23:00



Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In