Over the past few decades, a considerable scientific progress has been achieved in the area of fish welfare at all stages-farming, transportation, various pre-slaughter manipulations, stunning/killing procedures, etc. The increasing scientific interest is mainly due to the serious need of developing and implementing specific fish welfare requirements across the whole chain for both ethical (welfare) and commercial (meat quality) reasons. Since there has been substantial evidence that fish are able to experience pain and suffering, the provoked stress response could be a major cause of altered post-mortem metabolism and impaired meat quality. The present review was aimed to present the relationship between ante-mortem stress, course of postmortem metabolic processes and the potential alterations in some quality traits of fish for human consumption.

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Fish welfare at slaughter is an area of considerable scientific and commercial importance during the last decade. The aim of this study was to evaluate the effect of three stunning procedures on stress and meat quality of common carp. The experimental fish were separated in three groups and stunned by percussion (Group PS), electricity (Group ES) or asphyxia (Group AS), followed by decapitation. Blood cortisol and glucose concentrations were measured as stress indicators, whereas drip loss was used as meat quality parameter. The lowest glucose concentration (3.86±1.26 mmol/L) and drip loss (2.02±0.42%) were observed in Group PS. On the contrary, Group AS showed the highest results (11.34±3.07 mmol/L and 3.22±0.75% for blood glucose and drip loss, respectively), whereas the electrically stunned carp took an intermediate position (6.05±1.29 mmol/L and 2.29±0.43%). We conclude that percussive stunning leads to considerable reduction of stress at slaughter and better meat quality (lower drip loss), whereas asphyxia is unacceptable method due to the strong stress reaction and increased drip loss. Electrical stunning can be an effective method for stunning carp, but requires improvements of the electrical device to eliminate the repeated current application.

Percussive and electrical stunning are the most promising methods in terms of rendering fish unconscious prior to slaughter. The aim of this study was to determine the effect of these two stunning methods on postmortem muscle changes and meat quality of common carps. The experimental fish were stunned either by percussion (Group 1) or by electrical current application (Group 2), both followed by immediate decapitation. Muscle pH was measured at different time intervals to assess the postmortem metabolic changes, whereas meat colour, drip loss and water activity were used as quality parameters. The fish in Group 1 showed slightly accelerated postmortem muscle metabolism, higher redness (a*) and yellowness (b*) colour values and lower water activity. Percentage of drip loss after 4 days of storage at 4 °C did not differ significantly between the two groups. Based on the obtained results we concluded that both tested stunning methods were not associated with high levels of stress and significant detrimental effect on the meat quality of common carps.

Original Scientific ArticleMac Vet Rev 2016; 39 (1): [97][98][99][100][101][102] Since fluoroquinolones are one of the most commonly used antibacterial drugs in aquaculture, there is a risk of their residues to be found in the treated fish. The objective of this study was to examine the changes in enrofloxacin and ciprofloxacin levels during storage of rainbow trout and common carp muscle at -18 °C. The trout and carp were treated orally with a single dose of 10 mg/kg of enrofloxacin. Tissue samples were collected 24 h after the treatment and stored at -18 °C for 270 days either as a whole fish or as precut muscle samples. Results for trout revealed that in the precut samples enrofloxacin concentration decreased significantly only after 9 months of storage, whereas a significant decline in the ciprofloxacin level was observed much earlier (after 3 months). After 9 months of storage, the trout stored without being sliced and eviscerated showed significantly higher levels of both quinolones as compared to the precut muscle samples. The enrofloxacin levels in the carp musculature decreased considerably after 3 months of storage and stayed almost unchanged up to the end of the study, whereas the ciprofloxacin concentration continued to drop even after this period and after 270 days constituted 1/6 of the initial values.