2. Material and methods2.1. Fish ma

2. Material and methods
2.1. Fish material
The wild fish used in this study (unselected salmon, termed
WP) were offspring obtained from the Norwegian national gene
bank for wild Atlantic salmon (Direktoratet for Naturforvaltning,
Norway). The farmed salmon used in this study (selected salmon,
termed FP) were of the Mowi strain that has been subjected to artificial
selection in Norway since the 1970’s; these FP salmon were
obtained from the breeding nucleus of SalmoBreed AS, Norway.
The fish were hatched in November 2006 and kept separate, but
under the same conditions (temperature, flow rate, oxygen, fish
density, feed and feeding) until they reached tagging size (approximately
120 g) in August–September 2007. Each fish was individually
tagged using PIT-tags of 2.12  12.0 mm injected into the
buccal cavity. Subsequent to tagging, all fish were mixed and
reared communally until slaughter. The salmon were transferred
from freshwater to seawater in May 2008, reared in seawater at
the Bolaks AS facility on the Norwegian west coast, and harvested
at a commercial slaughter plant over the 7–9th of September 2009.
A random sample of FP and WP fish (n = 160) was slaughtered by
percussive stunning, bled and washed in running seawater,
machine filleted, and stored on ice in Styrofoam boxes until quality
analyses (mechanical properties and fillet fat content) were performed
four days post-mortem.