Butchering – Slaughtering – Stunning
Reexamination Certificate
1999-12-09
2001-02-06
Little, Willis (Department: 3643)
Butchering
Slaughtering
Stunning
C452S062000, C452S065000, C452S054000, C452S196000
Reexamination Certificate
active
06183356
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a method and apparatus for, the humane killing of fish and, although the invention has been developed in relation to the killing of salmon, the method and apparatus are applicable to the killing of other species of fish.
The present method of killing farmed salmon involves feeding the salmon on to a table where they are first stunned using a hand-held club or placed in a bath of sea water saturated with carbon dioxide. After stunning, the fish are killed/bled using a knife to cut the gill arches on one or both sides of the fish. This causes the blood of the fish to be discharged, i.e. it is an exsanguination process. The removal of the blood results in brain death and is believed to result in an improved quality for the flesh of the fish.
The present method described above is labour-intensive and, when the operators have been at work for a length of time, there is a possibility that the salmon will only be partially stunned before being killed.
It is accordingly an object of the present invention to provide an improved method and apparatus for the humane killing of fish.
SUMMARY OF THE INVENTION
According to a first aspect of the present invention there is provided a method for the humane killing of fish, which method includes.
a) causing a fish to move along a predetermined path,
b) halting such movement of the fish at a predetermined position along the path,
c) holding the fish at said predetermined position by releasable holding means,
d) stunning the fish,
e) killing the fish in such manner as to effect exsanguination of the fish, and
f) releasing the killed fish.
Holding, stunning and killing of the fish may all be effected by pneumatically-operated means. Stunning is preferably effected by the transfer of energy from a fast-moving impact member to the skull of the fish, resulting in concussion of the fish. Alternatively, stunning of the fish may be effected electrically.
Killing of the fish is preferably effected by a knife which is moved arcuately to enter the heart of the fish. The distance and path of travel of the knife are preferably such as to cause the knife to enter first the heart and then the brain of the fish. Killing of the fish may alternatively be effected by gill slitting. In such case, gill slitting is preferably effected using an elongated rotary cutting element.
According to a second aspect of the present invention there is provided apparatus for use in the humane killing of fish, which apparatus includes:
a) means defining a predetermined path along which a fish can be caused to travel,
b) stop means for halting the movement of the fish at a predetermined position along said path,
c) releasable holding means for holding the fish at said predetermined position,
d) stunning means for stunning the held fish,
e) killing means for killing the stunned fish in such manner as to effect exsanguination of the fish, and
f) means for releasing the killed fish.
If guide means are provided for defining the predetermined path, the guide means preferably comprises a pair of guide walls which define a generally V-shaped channel along which a fish can travel. The channel is preferably inclined to the horizontal with the arrangement such that a fish is fed into the higher end of the channel and passes gravitationally to the other, lower end of the channel.
The releasable holding means is preferably pneumatically-operated and serves to restrain the fish against any rearward or lateral movement when held at said predetermined position.
The two guide walls are preferably pivotally mounted on a support frame for relative pivotal movement about an axis above and substantially parallel to the predetermined path along which the fish is caused to move. The arrangement is preferably such that, at the beginning of a cycle of operations, the guide walls are in their supporting positions, in which the lower edges thereof are only a short distance apart, i.e. short in relation to the width of a fish so that the fish cannot drop through the gap between said lower edges, whereas, after the fish has been killed, the guide walls are moved away from each other to provide a gap through which the killed fish can drop. The two guide walls may be of generally clamshell configuration.
The stop means for halting movement of the fish preferably includes a movably mounted lever which is engaged by the leading part of the fish as it moves along the predetermined path, the lever being located at the end of the V-shaped channel along which the fish can travel. The lever is preferably an actuating member which initiates a cycle of operations of a number of pneumatically-operated elements.
The holding means is preferably the first element to operate during said cycle of operations. The holding means preferably includes a pair of air bags which are carried by the guide walls and are positioned so that they engage the sides of the fish. The holding means preferably also includes a pair of inflatable cheek pads which are positioned so that they can engage and restrain the sides of the leading part of the fish.
If the stunning means is electrically operated, it will preferably include a pair of electrodes mounted on the cheek pads. The electrification period may last for about 0.5 seconds and the current which is used should not exceed 200 milliamps.
The air bags and the cheek pads are preferably positively and rapidly inflated so as to move into engagement with the fish, such rapid inflation being effected by, for example, causing a chamber containing compressed air to discharge into the air bags and cheek pads. Rapid deflation of the air bags and cheek pads is preferably effected towards the end of the cycle of operations by, for example, a bellows-type suction device which withdraws the compressed air from the air bags and cheek pads.
Stunning of the fish, when held in position by the air bags and cheek pads, is preferably effected by means of a pneumatically-operated hammer. The hammer preferably comprises a mass having a generally domed presented face and carried on a stem which is movable axially towards the location of the brain of the fish. The stem preferably carries a piston at its other end, the piston being movable within a primary chamber linked to a pressure reservoir in such manner that, at the appropriate position in the cycle of operations of the apparatus, a valve connecting the pressure reservoir to the primary chamber is opened to effect a rapid increase in pressure within the primary chamber and hence rapid acceleration of the hammer towards the brain of the fish.
The acceleration applied to the hammer and the distance of travel of the hammer before the presented face thereof strikes the head of the fish is preferably such that, by the time the hammer strikes the head of the fish, the velocity of the hammer is at least 18 meters per second.
Internal buffering means are preferably provided between the piston and the end of the primary chamber to absorb any residual energy in the hammer after it strikes the head of the fish and the control means controlling the cycle of operations of the apparatus is preferably such as to return the hammer to its original position once the required impact has been applied to effect stunning of the fish.
Alternative stunning means include, as mentioned above, electrodes mounted on the cheek pads, or a cylindrical pin which is moved pneumatically so as to penetrate the brain of the fish. The pin may be either a solid pin or in the form of a tube through which compressed air or potassium chloride is injected into the brain, i.e. it is an asperated punch.
The means for killing the fish and effecting exsanguination thereof may be in the form of a knife of generally arcuate form arranged for pivotal movement about its center of curvature and movable under the control of a pneumatic piston and cylinder mechanism so that, a matter of microseconds after the fish has been stunned, the knife is moved upwardly, through the gap between the lower edges of the guide walls so as to pierce the heart of the fish and cause
Kestin Steven Charles
Middleton Ashley Paul
Little Willis
Middleton Engineering Limited
Stoltz Melvin I.
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