Mechanical analyses revealed significantly higher firmness of
the wild (338.8 ± 5.7 N*s) compared with the farmed salmon offspring
(308.8 ± 6.8 N*s) (Table 1). Fast growth has been found to
promote softness of salmon fillets (Mørkøre & Rørvik, 2001), but
there is limited knowledge on underlying causes of the correlation
between fast growth and softness. Einen, Mørkøre, Rora, and
Thomassen (1999) reported improved firmness in salmon fed
restricted feed rations, coinciding with higher ultimate muscle
pH and protein-bound hydroxyproline, and lower content of fat
and sarcoplasmic proteins. According to Swatland (1990), the connective
tissue (endomysium) associated with individual muscle
fibres cannot keep up with rapid muscle fibre growth and as a
result is less developed and immature.