WO1998044805A1

WO1998044805A1 - Method and apparatus for killing and bleeding fish

Info

Publication number: WO1998044805A1
Application number: PCT/NZ1998/000045
Authority: WO
Inventors: Michael W. Hitchins
Original assignee: Indac Ltd.
Priority date: 1997-04-04
Filing date: 1998-04-03
Publication date: 1998-10-15
Also published as: AU7086798A

Abstract

Apparatus (11) comprises a fish restraining device (18), a fish positioning device (19), a killing device (13) for fatally injuring the brain of a fish (14), a device (15) for cutting the throat of the fish (14) and a device (16) for opening the gills of the fish (14). Killing device (13) for fatally injuring the brain of fish (14) comprises a blade or spike (20) designed to pierce the brain or spinal cord. Alternatively the device (13) may comprise an impacting device to crush the brain or it may comprise a laser or any other suitable electrical device to fatally injure the brain of the fish (14). Methods of using apparatus (11) are also claimed.

Description

METHOD AND APPARATUS FOR KILLING AND BLEEDING FISH

The way in which fish are killed effects the overall quality of the fish both visually and in taste and therefore care must be taken during killing and bleeding to minirnise damage to the flesh.

At present fish are placed into a tank or tray by a fish handling device e.g. a fish pump, elevator or by hand and immobilised by adding drugs to the water of the tank. Alternatively, the fish may be immobilised by gassing with, for example C0₂, or they may be stunned either by passing an electric current through the water or by using an electric stun gun.

Once the fish are immobilised, the fish are removed from the tank by hand to a killing tray and killed by impact to the brain, hand spiking to the brain and if desirable, throat cutting. For example, with a fish such as salmon, the throat is always cut in order to bleed the fish and preserve the quality of the product. The fish are then weighed and placed on an ice slurry.

One problem encountered by this current practice is that the fish may be bruised by handlers gripping the fish too tightiy or by impacting and/or spiking in the wrong place. Additionally, blood clots may form if the fish are not bled properly. Both bruising and the formation of blood clots affects the quality and taste of the fish and ultimately the economic value of the fish. Moreover, manual handling of each fish during the killing operation can be very stressful to the fish and be labour intensive, time corisuiriing and, therefore, expensive.

The present invention overcomes, at least to some extent, the problems aforesaid.

According to the present invention there is provided a method for killing fish comprising the steps:

(a) restraining at least the head of a fish in a restraining device, (b) positioning the fish so that the brain of the fish is directly below a killing device which can be operated to fatally injure the brain;

(c) activating the killing device to fatally injure the brain of the fish and

(d) releasing the fish for further processing.

The activation of the killing device may be achieved automatically. Desirably, the fish is immobilised prior to delivery to the restraining device. Conveniently, the bqdy.and head of the fish is restrained by the restraining device. The fish may be presented to the restraining device by placing the fish, either by hand or by mechanical means, into a controlled slide shute, the fish being delivered via the shute to the desired restraining position.

The fish may travel along the slide shute either by gravity, lever mechanism or vacuum device to the restraining device. The restraining device may comprise a frame or shute.

The fish may be restrained in the restraining device by a vacuum or any other suitable method, for example, by applying positive pressure against the fish or by wedges, in readiness for killing.

The fish may be held in the positioning device by hand.

The fish, once restrained, is positioned so that its brain is directly below the killing device by moving the fish into a positioning device which cradles the face of the fish and acts as a "stop".

The killing device may include a spike or knife, arranged to penetrate the brain or spinal cord, or the brain may be crushed by impact. Alternatively the brain of the fish may be fatally injured using a laser or other suitable electrical device.

More desirably, the method for killing fish may also comprise a method of bleeding fish wherein the throat of the fish is cut either at the same time as the fish is killed or shortly thereafter. Bleeding may be accomplished using a blade located proximate the restraining device and operable to cut into the throat or gill region of a restrained fish. Simultaneously or sequentially, the gills of the fish may be opened by any suitable device, for example, by vacuum suction caps, levers, wedges or hooks.

The shape of the blade which cuts the throat may be designed to remove a portion of the main artery carrying blood to the gills. In this way, clotting or coagulation of the blood is rmrurnised and blood is drained faster and more efficiently. The blade may bejflat, pointed or hollow or a barbed spike may be used. The blade or spike may enter the throat of the fish either by straight, oblique or rotary motion. Where the knife blade is hollow, it may be attached to a vacuum suction for the extraction of blood.

Alternatively the fish may be bled by a single blade cutting the throat as is done presently by hand.

A suction device may be used to withdraw blood from the fish. Conveniently, the blood is stored or passed immediately for further processing. For example, the extracted fish blood may be used to make other vendible products.

The extraction of blood may take place in the killing station or in a subsequent treatment station.

Additionally, a mechanical knife or saw may be positioned to open the stomach of the fish in readiness for gutting.

Once the fish have been killed and optionally bled, the fish may be released from the restraining device and may be sent for further processing, e.g. weighing, grading, storage, via a set of controlled slide shutes or by hand.

According to a further aspect of the invention there is provided an apparatus for killing fish comprising a fish restraining device, a killing device for fatally injuring the brain of the fish and a positioning device which acts to align the head of the fish with the killing device. As discussed above, in relation to the method of the invention, the apparatus may further comprise one or more of the following: a device for cutting the throat of the fish, a gill opening device and a blade or saw for cutting the stomach of the fish in readiness for gutting.

The apparatus may further comprise a controlled slide shute from an immobilisation tank to deliver fish to the fish restraining device and positioning device.

The fish restraining device may comprise a formed frame or shute with vacuum attachments to enable the fish to be held in position by vacuum pressure. Alternatively the formed frame or shute may comprise hydraulic fittings or other means enabling the frame or shute to compress around the fish and hold the fish in position by the application of positive pressure. In both cases a miriimum amount of force is exerted so as not to damage the flesh of the fish.

The positioning device may comprise a "V" like structure for cradling the face of a fish and acts as a "stop" to position the brain of the fish directly below the killing device. The killing device may comprise a blade or spike designed to pierce the brain or spinal cord. Alternatively, the killing device may comprise an impacting device to crush the brain or it may comprise a laser or any suitable electrical device to fatally injure the brain of the fish.

The device for cutting the throat of the fish may comprise a flat, pointed or hollow knife blade or a barbed spike. The device may be designed to enter the throat of the fish in a straight, oblique or rotary motion and may be further designed to remove some of the main artery which carries blood to the gills. Where the device comprises a hollow blade, this may be attached to a vacuum device for extracting the blood.

The device for opening the gills of the fish may comprise vacuum suction cups, levers, wedges or hooks.

The fish restraining device may release the fish after killing and bleeding by opening at the bottom or side(s) to send the fish to a further shute for further processing. The apparatus may be arranged to comprise a plurality of fish restraining and positioning devices arranged in linear or a rotary (carousel) design and the apparatus may be controlled by a logic controller to fully automate the killing and bleeding of fish.

The apparatus may comprise a sensor to assess the size of the fish and effect the positioning of the fish brains below the killing device.

The apparatus may be manually or electronically operated to effect killing, and optionally, bleeding, gill opening and stomach slitting, either simultaneously or sequentially.

The invention will be further apparent by the following description with reference to the accompanying drawing in which:

Figure 1 shows the apparatus of the present invention in operation, and Figure 2 illustrates one form of spike useable in the apparatus of figure 1.

Referring to figure 1, one preferred apparatus of the invention is illustrated. The apparatus 11 comprises a fish restraining device 18, a fish positioning device 19, a killing device 13 for fatally injuring the brain of a fish 14, a device 15 for cutting the throat of the fish 14 and a device 16 for operiing the gills of the fish 14.

The fish restraining device 18, comprises a frame or shute to restrain the head and body of the fish 14. The shute or frame is preferably made from a polyethylene material which may be vacuum moulded or otherwise formed into the desired shape. The shute is preferably mounted on an incline support so that gravity assists in moving the fish into the positioning device.

The positioning device 19, comprises a "V" shaped structure which cradles the face of the fish and acts as a "stop", aligning the brain of the fish 14 below killing device 13 and the throat of the fish 14 directly above the device 15 for cutting the throat. The killing device 13 for fatally injuring the brain of a fish 14 comprises a blade or spike 20 designed to pierce the brain or spinal cord. Alternatively the device 13 may comprise an impacting device to crush the brain or it may comprise a laser or any other suitable electrical device to fatally injure the brain or the fish 14.

Figure 2 illustrates one preferred form of spike 20. The spike 20 comprises a rod-like portion 20b and a terminal spigot 20a, that project from the outer end 20c of the rod 20b_.. The rod 20b is mounted in a reciprocating apparatus that is positioned to enable the spike to be moved to impact a fish to be killed.

The reciprocating apparatus (not shown) may be pneumatically operated. In this case, it has been found to be advantageous to use a lower air pressure to return the spike to its initial or "ready" position. Use of a lower return pressure reduces the air resistance to forward motion of the spike and thus facilities rapid acceleration of this spike into impact with the fish.

The spigot 20a operates to locate the spike during initial contact with the fish, and prevent subsequent slippage, the flat end 20c then blanks or moves a larger part of the fish bone/cartilage which moves inwardly, taking an expanding amount of material to impact the fishes brain and cause death. The spike 20 may be of any suitable material, such as stainless steel or tool steel. A spike having a rod portion of about 4 mm diameter and a spigot of up to 0.5 mm diameter has been found to be effective.

The device 15 for cutting the throat of the fish 14 comprises a flat, pointed or hollow knife blade 21 or a barbed spike. The device is designed to enter the throat of the fish 14 in a straight, oblique or rotary motion and may be designed to remove a portion of the main artery carrying blood to the gills. In this way coagulation of the blood, which may affect the quality of the fish, is avoided. Where the blade 21 is hollow, this is connected to a vacuum device for extracting the blood (not shown).

The device 16 for opening the gills of the fish 14 comprises vacuum suction cups, levers, wedges or hooks 22. The fish restraining device 18 comprises openings at the bottom 23 to release the fish therefrom into a shute (not shown) to be transported to another area for further processing.

Alternatively the apparatus 11 is inclined at an angle and the "V" shaped positioning device 19 moves aside and the fish slides out for further processing.

Optionally, the apparatus 11 comprises a saw or blade 24 for cutting the stomach of the fish open in readiness for gutting.

In operation, a fish 14 is immobilised in an immobilising tank by known methods for example by adding, sedative drugs to the water of an immobilisation tank, by gassing the tank water with C0₂ or by stuiiriing the fish by passing electrical currents through the tank water, and transferred to the restraining device 18 of apparatus 11 either by hand or mechanically using a vacuum operated shute (not shown).

The fish's face is cradled in the positioriing stop 19 and the fish's body is held firmly in the frame or shute 18, either by vacuum or positive pressure means, so that the brain, throat, and gills of the fish are directly in line with the devices 13, 15 and 16.

The devices 13, 15 and 16 are electronically or manually controlled and may be set to simultaneously or sequentially fatally injure the brain, cut the throat and open the gills of the fish 14. The positioriing of the devices 13, 15 and 16 may be variable, particular positions being selected to suit particular sizes or species of fish.

A pressure sensor may be present in the positioning device 19 so that when the face of the fish 14 touches the positioning stop 19 the killing device 13 automatically kills the fish. The pressure sensor may also be connected to devices 15 and 16 so that as soon as the fish enters the positioning device 19, the blade 20 of the killing device 13 is lowered to fatally injure the brain of the fish 14, the blade 21 of device 15 is raised to cut the throat of the fish 14 and the vacuum cups, levers or hooks 22 of device 16 pull open the gills of the fish either simultaneously or sequentially. Once killed and bled, the shute 18 opens at the bottom 23 to release the fish 14 into another shute (not shown) to be transported to another area for further processing.

The apparatus 11 may comprise a plurality of fish restraining and positioriing devices 18, 19 arranged in a linear or carousel fashion to enable full automation of fish killing and bleeding to take place. Such apparatus may be controlled by a logic controller.

Blood removed from the killed fish may be passed to a further station for processing or storage. If the blood is to be processed, it may be advantageous to use a vacuum or other suction device to remove the blood. This could be effected at the killing station or in a subsequent processing station.

Wherever possible, easily cleanable materials such as moulder polyethylene are used. This ensures that the apparatus can be maintained in a hygienic condition and thus reduces die risk of infection such as salmonella and lysteria.

It will be appreciated that it is not intended to limit the invention to the above example only, many variations, such as might readily occur to a person skilled in the art, being possible without departing from the scope of the invention.

Claims

WHAT WE CLAIM IS:

1. A method for killing fish including the steps:

(a) restrairiing at least the head of a fish in a restraining device;

(b) positioning the fish so that the brain of the fish is directly below a killing device which can be operated to fatally injure die brain;

(c) activating the killing device to fatally injure the brain of the fish; and

(d) releasing d e fish for further processing.

2. A method according to claim 1 , wherein the fish is immobilised prior to delivery to me restraining shute.

3. A metiiod according to claim 1 or claim 2, wherein me body and head of die fish are restrained by the restrairiing device.

4. A memod according to any one of claims 1 to 4, wherein the fish is presented to the restraining device by placing the fish, either by hand or by mechanical means, into a controlled slide shute, die fish being delivered via die shute to the desired restraining position.

5. A method according to claim 4, in which me fish travels along the slide shute ei╧ìier by gravity, lever mechanism or vacuum device to the restraining device.

6. A method according to any one of claims 1 to 4, wherein die restraining device comprises a frame or shute.

7. A method according to any one of me preceding claims, in which the fish, once restrained, is positioned so that its brain is directly below the killing device by moving the fish into a positioning device which cradles die face of the fish and acts as a "stop" .

8. A med od according to any of the preceding claims, in which die killing device includes a spike or knife, arranged to penetrate the brain or spinal cord, or the brain may be crushed by impact.

9. A method according to any one of claims 1 to 7, wherein die brayi of the fish is fatally injured using a laser or other suitable electrical device.

10. More desirably, die mediod for killing fish may also comprise a mediod of bleeding fish, wherein die diroat of the fish is cut eiti er at d e same time as die fish is killed or shortly tiiereafter.

11. A method according to any one of claims 1 to 10, in which die blade is shaped to cut and to remove a portion of me main artery carrying blood to die gills.

12. A mediod according to any one of the preceding claims, wherein the blade is flat, pointed or hollow and in which the blade or spike enters die throat of die fish either by straight, oblique or rotary motion.

13. A method according to any one of claims 1 to 12, in which a suction device is used to wididraw blood from die fish.

14. A method according to any one of claims 1 to 13, in which the blood is stored or passed immediately for further processing. For example, me fish blood may be used to make otiier vendible products.

15. An apparatus for killing fish comprising a fish restraining device, a killing device for fatally injuring die brain of die fish and a positioning device which acts to align die head of die fish widi the killing device.

16. Apparatus according to claim 15, further comprising, optionally, one or more of the following: a device for cutting the throat of the fish, a gill opening device and a blade or saw for cutting the stomach of the fish in readiness for gutting.

17. Apparatus according to claim 15, further comprising a controlled slide shute from an immobilisation tank to deliver fish to die fish restraining device and positioning device.

18. Apparatus according to any one of claims 15 to 17, wherein die fish restraining device comprises a formed frame or shute widi vacuum attachments to enable die fish to be held in position by vacuum pressure, a formed frame or shute widi hydraulic fittings or other means enabling die frame or shute to compress around die fish and hold die fish in position by die application of positive pressure.

19. Apparatus according to any one of claims 15 to 18, in which e positioning device comprises a "V" like structure for cradling die face of a fish and acts as a "stop" to position die brain of die fish directiy below die killing device.

20. Apparatus according to any one of claims 15 to 19, wherein die device for cutting the throat of the fish comprises a flat, pointed or hollow knife blade or a barbed spike.

21. An apparatus according to any one of claims 15 to 20, including a plurality of fish restraining and positioning devices arranged in linear or a rotary design and die apparatus may be controlled by a logic controller to fully automate die killing and bleeding of fish.

22. An apparatus according to any one of claims 15 to 21 , further comprising a sensor to assess die size of the fish and effect die positioning of the fish brains below die killing device.

23. An apparatus according to any one of claims 15 to 22, further comprising means for removing and transporting blood from die fish for subsequent processing.