Dear Group:
Is there a percentage difference of oil's between wild and farmed raised
salmon. Is one more less or the same.
I can provide some data for Atlantic salmon, Salmo salar.
Three papers give lipid contents of large samples of farmed salmon. The
summary results are:
Scottish salmon, mean =10.1%, n = 495, s.d = 2.9, (Bell et al);
Irish salmon, mean = 11.9%, n = 692, s.d = 2.43, (Schallich & Gormley);
Norwegian salmon, mean = 15.0%, n=145, s.d = 3.0, ( Refsgaard et al).
You will see that the lipid content is high, but perhaps just, if not more,
important is the high variation. Assume an S.D. of 2.5 for ease of
calculation and this implies a 95% range of + or - 5 percentage units from
the mean. Diet has an impact on lipid content, but is small compared with
biological variation. Bell et al's data came from 5 fish farms using feeds
of different lipid contents. There was a weak association between lipid
content in the diet and lipid content in the flesh, but this was almost
completely obscured by the spread of values around the regression line.
It is usually considered, in Scotland at least, that the lipid content of
wild salmon is around 7%, but I cannot cite a reference. Shallich & Gormley
found the lipid content of 295 Irish wild salmon to be 12.25% with an s.d
of 3.01, essentially not different from the farmed salmon. Andersen et al
gives a mean lipid content of 6 samples of wild Atlantic salmon 'caught
off-shore from Canada' of 9.27%. Auersand et al measured lipid contents in
different parts of Atlantic salmon and cites in the discussion a range of
5-8% lipid content in wild salmon. The lipid content in the flesh drops
when gonads form, (Aksnes et al), but typically farmed salmon are harvested
before they become mature.
The high, and in particular, the very variable, lipid contents in famed
salmon presents problems for salmon smokers because salt penetration and
drying rate in the kiln are influenced by lipid content. It is therefore
difficult to get a consistent cure within a batch of fish.
I am sure there will be data available for other species of salmon, but I
do not have references.
REFERENCES
Aksnes, A., Gjerde, B. & Roald, S.O., 1986. Biological, chemical and
organoleptic changes during maturation of farmed Atlantic salmon, Salmo
salar. Aquaculture, 53, 7-20
Andersen, H.J., Bertelsen, G., Christophersen, A.G., Ohlen, A. & Skibsted,
L.H. 1990.
Development of rancidity in salmonoid steaks during retail display. A
comparison of practical storage life of wild salmon and farmed rainbow
trout. Zeitschrift für Lebensmittel-Untersuchung und -Forschung, 191,
119-122.
Aursand, M., Bleivik, B., Rainuzzo, J.R., Jørgensen, L. & Mohr, V. 1994.
Lipid distribution and composition of commercially farmed Atlantic salmon
(Salmo salar). Journal of the Science of Food and Agriculture, 64, 239-248.
Bell, J., McEvoy, J., Webster, J.L., McGhee, F., Millar, R.M. & Sargent,
J.R. 1998.
Flesh lipid and carotenoid composition of Scottish farmed Atlantic salmon
(Salmo salar).
Journal of Agricultural and Food Chemistry, 46, 119-127.
Refsgaard, H.H.F., Brockhoff, P.B. & Jensen, B. 1998. Biological variation
of lipid constituents and distribution of tocopherols and astaxanthin in
farmed Atlantic salmon (Salmo salar). Jurnal of Agricultural and Food
Chemistry, 46, 808-812.
Scallich, E. & Gormley, T.R. 1996. Condition factor, fat content and
flavour of famed and wild salmon. Farm & Food, 6(3), 28-31.
Peter Howgate
Aberdeen, Scotland, UK