The objectives of the proposed research are: an optimization of slaughter processes of cultivated fish with respect to fish quality and welfare and b. automation and application of optimum procedures on pilot scale
State of progress
The inventory study of slaughter methods used by industry was finished for eel, gilt head bream and salmon. Protocols for measuring effects of slaughter on welfare of eel, gilt head bream and salmon were finished.
Eel. Welfare aspects of stunning methods. Participants 01, 02 an 08 performed slaughter experiments with eels at the facilitities of the SME, Royaal B.V. for eel (participant 08). The following stunning methods were evaluated: electrocution, stunning by adding Aqui-S to water, percussive stunning by clubbing by hand, destroying the brains by using a hollow punch, the industrial method (the so-called salt bath), used at participant 08.
The behaviour of fish at slaughter was monitored by using the welfare protocol.
Eel. Quality aspects of stunning methods. Participant 02 studied several methods to deslime stunned eel. In industry eel is deslimed alive in a salt bath. Desliming of stunned eel in salt bath is not possible without modifications.
Participant 01 slaughtered two batches of eel to evaluate the effects on fish flesh quality. The industrial method used at Royal and an experimental method which consisted of stunning with Aqui-S in combination with the air nailer for pin-bolting were used for slaughter.
Gilt head bream. Quality aspects of stunning methods. Experiment 1 was carried out at the CUPIMAR (subcontractor of participant 04) facilities in San Fernando, Cadiz province, Spain, in March 1998. Killing and preparation of lots were carried out by participants 1, 3 and 4. The following killing methods were used: lot: death in ice-water, lot 2: death in air, lot 3: anaesthesia (AQUI-S) and lot 4: a blow on the head. Experiment 2 was also carried out at CUPIMAR Four lots were prepared: control lot (c.i.): Death in ice-water. Not gutted. Killing and treatment conditions as in experiment 1 for lot 1, lot 1: Death in ice-water, gutted, lot 2: Death in air, gutted and lot 4: A blow on the head followed by ice-water, gutted.
On this occasion there was no lot treated with AQUI-S (Lot 3), as this had been shown not to produce effective anaesthesia.
Gilt head bream. Welfare aspects of stunning methods. Behaviour of the fish was monitored when the fish were slaughtered in Experiment 1 by participant 03, 04 and 01.
Salmon. Quality aspects of stunning methods. Slaughter experiments with Atlantic salmon at participant 05 and 06 were conducted. Four methods to anaesthetise the fish were tried: carbon dioxide, 4 min. exposure, followed by gill cutting, pin-bolt, followed by gill cutting, electric stunning, followed by gill cutting and as gill cutting control. Quality changes were monitored. Using the protocol.
Salmon. Welfare aspects of stunning methods. A preliminary experiment to investigate some current slaughter methods used for Atlantic salmon was performed. This was carried out in Tromso by participant 03 in conjunction with Participant 05. The three methods chosen were: percussion stunning and gill slitting without a prior stun (two commercial methods) and pin bolting (an experimental method).
Participant 07 and 05 performed a desk study on prototype equipment for stunning and contacted manufacturers of prototype equipment.
An overview of slaughter methods used by industry was finished for eel, gilt head bream is available. Protocols for measuring effects of slaughter on welfare of eel, gilt head bream and salmon are available.
Effects of the industrial slaughter method and an experimental method (Aqui-S in combination with pin-bolting) on quality and welfare of eels was measured. A cheap method for desliming of stunned eel was developed.
Effects of the industrial slaughter method (hypothermia) and an experimental methods (Aqui-S and blow on the head) on quality and welfare of gilt head bream was measured.
A study of effects of industrial and research slaughter methods on quality and welfare of salmon is in progress.
The replies to the questionnaires, to obtain information from the salmon industry on slaughter are available.
V Future actions
Mid-term review. It was decided that the Mid-term review should be the subject of the plenary meeting in June 1999. Each technical group will have to prepare a report for this meeting.
Workshop. In addition, plans should be made at the plenary meeting in June 1999 for a workshop to disseminate the results.
Description of work
The study will be undertaken on salmon (Salmo salar), gilt-head bream (Sparus aurata) and eels (Anguilla anguilla).
An inventory study of effects of industrial slaughter methods on eating and keeping quality was carried out. Methods to evaluate effects of slaughter on quality and welfare were standardised.
The effects on quality of slaughter methods used by industry will be compared with methods chosen for research. Welfare aspects of these methods were evaluated by monitoring fish behaviour.
Existing prototype equipment was evaluated in a desk study and in discussed with manufacturers
Funding SchemeCSC - Cost-sharing contracts
AB25 1HG Aberdeen
BS40 5DU Bristol