Effects of husbandry stress on flesh quality indicators in fish

Many husbandry procedures are unavoidably associated with a degree of stress and may also be accompanied by the imposition of physical exertion upon the fish. Even the most minor of disturbances can have profound effects on the physiological status of fish and these elements may contribute to undesirable changes in the characteristics of the flesh of fish post-slaughter. The depletion of muscle phosphagen, glycogen and ATP levels together with an accumulation of lactic acid and a resulting decline in pH are features common to both stressed and exercised fish. Although equivocal and contradictory in some respects, the available data suggest that pre-slaughter husbandry practices can have significant effects upon flesh quality in fish. The adverse changes in the muscle of fish following slaughter are primarily related to the extent to which muscle metabolites are depleted before death and this in turn is directly related to the severity of the exercise and/or stress which is imposed upon the fish prior to slaughter. The most consistently reported effect of pre-slaughter disturbance is an increase in the rate of onset of rigor mortis.