The effect of a shielding skirt, a tarpaulin mounted from the surface down to 5 m depth around a net cage, on the flow pattern at a commercially stocked salmon cage was investigated. Dye was used as a tracer for water movement and the dye spreading was monitored using aerial images. Current meters were employed to investigate the flow close to the net inside and outside the cage. Tests were conducted with and without the shielding skirt. The focus was on the effectiveness of the shielding skirt to deflect water around the cage. This study shows that a shielding skirt can reduce horizontal flow components significantly inside a cage, which is related to a reduction of water exchange. The flow toward a cage is divided by a shielding skirt, i.e., some of the water is transported around the cage, while some is passing underneath the shielding skirt. Some water entering the fish cage from underneath the tarpaulin is transported toward the surface inside the cage. The use of a shielding skirt might not prevent interaction of the upper water layers inside and outside of a fish cage completely, but it has the potential to reduce the inflow of surface water into the cage, if deployed properly.

References

References
1.
Statistics of the Food and Agriculture Organization of the United Nations,
2012
, Accessed Aug. 6, 2014, http://www.fao.org/fishery/statistics/global-aquaculture-production/en
2.
Costello
,
M. J.
,
2006
, “
Ecology of Sea Lice Parasitic on Farmed and Wild Fish
,”
Trends Parasitol.
,
22
(10)
, pp.
475
483
.10.1016/j.pt.2006.08.006
3.
Hevrøy
,
E. M.
,
Boxaspen
,
K.
,
Oppedal
,
F.
,
Taranger
,
G. L.
, and
Holm
,
J. C.
,
2003
, “
The Effect of Artificial Light Treatment and Depth on the Infestation of the Sea Louse Lepeophtheirus Salmonis on Atlantic Salmon (Salmo Salar L.) Culture
,”
Aquaculture
,
220
(1–4)
, pp.
1
14
.10.1016/S0044-8486(02)00189-8
4.
Næs
,
M.
,
Heuch
,
P. A.
, and
Mathisen
,
R.
,
2012
, “
Bruk av «luseskjørt» for å Redusere Påslag av Lakselus Lepeophtheirus Salmonis (Krøyer) på Oppdrettslaks
,” Vesterålen Fiskehelsetjeneste (in Norwegian).
5.
Lien
,
A. M.
, and
Høy
,
E.
,
2011
, “
Skjørt for Skjerming mot lus i Laksemerd
,” SINTEF Fiskeri og Havbruk AS, Report Number A19396, (in Norwegian).
6.
Lien
,
A. M.
, and
Volent
,
Z.
,
2012
, “
Deformasjon av not og Permaskjørt og Krefter på Fortøyning
,” SINTEF Fiskeri og Havbruk AS, Report Number A23184, (in Norwegian).
7.
Stien
,
L. H.
,
Nilsson
,
J.
,
Oppedal
,
F.
,
Kristiansen
,
T. S.
,
Lien
,
A. M.
, and
Folkedal
,
O.
,
2012
, “
Skirt Around a Salmon Sea Cage to Reduce Infestation of Salmon Lice Resulted in Low Oxygen Levels
,”
Aquacult. Eng.
,
51
, pp.
21
25
10.1016/j.aquaeng.2012.06.002
8.
Standard Norge,
2009
, “
Norwegian Standard NS 9415.E:2009. Marine Fish Farms—Requirements for Site Survey, Risk Analyses, Design, Dimensioning, Production, Installation and Operation
,” Standard Norge, Lysaker.
9.
Gansel
,
L.
,
Rackebrandt
,
S.
,
Oppedal
,
F.
, and
McClimans
,
T. A.
,
2014
, “
Flow Fields Inside Stocked Fish Cages and the Near Environment
,”
ASME
J. Offshore Mech. Arct. Eng.,
163
(
3
), p. 031201.10.1115/1.4027746
10.
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
(
1–4
), pp.
283
293
.10.1016/0044-8486(88)90062-2
11.
Fredheim
,
A.
,
2005
, “
Current Forces on Net Structures
,” Ph.D. thesis 2005:64, Department of Marine Technology, Faculty of Engineering Science and Technology, Norwegian University of Science and Technology, Trondheim, Norway.
12.
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 salarL.) in Production Cages
,”
Aquaculture
,
265
(1–4)
, pp.
271
287
.10.1016/j.aquaculture.2006.12.047
13.
Rackebrandt
,
S.
,
2008
, “
Water Flow in and Around Fish Cages
,” Norwegian University of Science and Technology, Norway, Report No. 28.
You do not currently have access to this content.