NO347011B1 - Fish stunning and bleeding arrangement and a method - Google Patents

Description

Technical Field

[0001] The present invention relates to a fish stunning and bleeding arrangement and a method for stunning and bleeding fish, in particular but not exclusively farmed salmon.

Background Art

[0002] Fish above a certain size is predominantly killed by cutting the throat of the fish. The killing is done this way not only to quickly kill the fish, but also to let out as much blood as possible from the fish. Blood remaining in the fish may discolour the fishmeat. Discoloured fishmeat results in a lower grade for the fish, and it may be regarded as unfit for human consumption. Hence, as soon as the fish has been cut, it is brought into a vessel containing preferably cold water. The cold water will delay the coagulation of the blood, so that as much blood as possible can be drained from the fish.

[0003] There are known a range of arrangements for propagating the bleeding of the fish:

[0004] EP 3367806 shows an arrangement where the killed fish is conveyed through a pipeline through different zones with different properties regarding air pressure and water flow.

[0005] WO 1997/01958 shows an arrangement where the fish is subjected to anaesthetics before being cut. The fish is conveyed between tanks with falling temperatures from 10°C to 1 °C before cutting and into a tank with a water temperature 1 ,5 - 2°C after the cutting.

[0006] EP 3599872 / WO2018/173078 shows a bleeding tank with a paddle wheel to convey the fish therethrough.

[0007] W02020/031215 A1 describes a method, a system and an apparatus for treating food items, for instance fish. The device and method use temperature differences and agitation to treat the freshly slaughtered fish and treat live fish against parasites.

[0008] FHF/Nofima has a current project on the possibility to use ultra-low temperatures to stun fish before cutting. The hypothesis is that a liquid with an ultralow temperature, such as down to -20°C, will cool the blood between the gills and the brain and lead to a shock that inflicts loss of conciseness. A short time cooling at this temperature will not cause the heart to stop and prevent bleeding after cutting. The project is described on https://www.fnf, no/prosjekter/prosjektbasen/901622/.

Summary of invention

[0009] There is a definitive need for a process arrangement that effectively can process live fish from a pen to a cut and bled-out and cooled or frozen state.

[0010] It is a desire to be able to install such an arrangement on a vessel, such as a supply ship with sufficient deck space, a barge or raft that can be transported between pens and different farming facilities.

[001 1] In its basic form, the invention provides a fish stunning and bleeding arrangement, comprising a process line having an intake into which live fish is fed, a sorting station downstream of said intake, said sorting station having at least two outlets, of which at least a first outlet is capable of being coupled to a stunning tank capable of containing a liquid at an ultra-low temperature, said ultra-low temperature is preferably -18 °C or lower, a stunned fish pump downstream of said stunning tank, a separator downstream of said stunned fish pump, and a cutting station downstream of said separator, said separator separating said liquid from said fish; a recirculating unit returning said liquid from said separator to said stunning tank, wherein a second outlet from said sorting station is coupled to a live fish pump, said live fish pump having an outlet coupled to a pen or tank for keeping live fish.

[0012] According to a preferred embodiment of the invention, the arrangement has the possibility to perform stunning of the fish through immersing the fish in a liquid having an ultra-low temperature, such as down to -21 °C, which is the theoretical freezing temperature for brine containing sodium chloride. If calcium chloride is used, the theoretical freezing temperature can be as low as -51 °C.

[0013] In a practical embodiment, the temperature will be 1-3 degrees higher to ensure that the liquid does not freeze and block the circulation.

[0014] The arrangement preferably has a so-called RID pump, which comprises a helically wound and rotating tube.

[0015] Further preferably, the ultra-low temperature liquid is circulated in a substantially closed circuit.

[0016] The barge or raft may have its own propulsion to be able to move between pens in a farming facility. If the maximum speed is below 4 knots, a certificate is not needed to manoeuvre the vessel, according to present Norwegian regulations.

Transport between different facilities can be done using a boat for towing.

[0017] Rafts and barges are already widely in use in fish farming. One such raft is “Miljøflåten”, which is equipped with a delousing system and is described in https://ilaks.no/miljoflaten-er-pa-plass-hos-nordlaks/.

[0018] The invention also relates to a method for stunning and bleeding fish, wherein live fish is pumped from a pen or tank to a sorting station, said sorting station sorting said fish at least into a stunning liquid at an ultra-low temperature, said stunned fish being transported in said stunning liquid to a separator, where said stunning liquid is separated from said fish, said fish being cut downstream of said separator and transferred to at least one bleed-out tank, while said stunning liquid is returned to join new fish to be stunned upstream of said separator.

[001 9] Further advantageous embodiments are defined in the dependent claims. Brief description of drawings

[0020] The invention will now be described in more detail, referring to a preferred embodiment shown in figure 1 , which shows a layout of the preferred embodiment. Detailed description of the invention

[0021] Referring to figure 1 , the preferred embodiment of the invention will now be described.

[0022] A line 1 is in communication with a fish and water intake (not shown). The intake is conveniently submerged into a pen and fish and water is sucked into the line 1. An inlet pump 2 provides the suction for the fish and water. The inlet pump is preferably an RID pump. The principles on an RID pump are e.g. described in NO330892.

[0023] Downstream of the inlet pump 2 is a combined delousing and sorting unit 3. Here the fish is deloused. The delousing can be done by chemicals, jet sprays, brushes, laser, warm water or any other suitable means. Lice that are removed from the fish as well as the water from the pen are separated from the fish and after filtering of the water and colleting the lice, the water is conducted back into the sea (not illustrated).

[0024] Downstream of the delousing the fish is sorted. The fish that is below a predetermined size if led into a small fish pipe 4, through a small fish pump 5 and onwards to a first exit pipe 6. The exit pipe 6 may conveniently feed the fish into a separate pen (not shown) where it can be fed to increase the size. The pump 5 is preferably an RID pump.

[0025] The larger fish is led into a large fish pipe 7. The large fish pipe 7 extends through a brine tank 8. At least a section 9 of the pipe 7 is perforated within the tank 8, so that bine is sucked into the pipe 7. The solution illustrated by the tank 7 and the perforated section 8 is explained in detail in the earlier filed Norwegian patent application 20210170, which is incorporated herein by reference.

[0026] Brine is supplied to the tank 8 from a brine mixer 10 through a brine supply line 11 , as well as from an RSW brine cooling and recirculating unit 12. This ensures that the tank 8 is always filled to a level above the perforated section 9.

[0027] Downstream of the tank 8, the pipe 7 is coupled to a large fish pump, or stunned fish pump, 13, which preferably also is an RID pump. The outlet 15 of the pump 13 is coupled to a four-way valve 14, which can select between a second exit pipe 16, for pumping fish to a pen or other keep for fish, a line 17 extending to a receiving boat for live fish or a processing plant, or a cut line 18 extending to a separator 19.

[0028] At the separator 19, brine and water are separated. The brine is collected and circulated back through a return line 20 to the brine cooling and recirculating unit 12, where the brine is cooled and fed into the tank 8 so that it again can be used for pumping fish through the pump 13. At this station, any lumpfish that may have escaped the sorting at the sorting station 3 will be collected for later return to the pen.

[0029] After draining, the fish is transferred to a cutting table 21 and cut at the throat. This can be done manually or automatically or semi-automatically by per se well-known means. Optionally, the fish may also be gutted at this stage.

[0030] The cutting table 21 may be equipped with a flat conveyor to transport the fish form the incoming end to the exiting end of the table 21 . It conveniently also has a bleed container to receive blood runnings from the cut fish.

[0031] The initial bleeding of the fish is done into the bleed container. At the end of the table 21 , the fish is transferred to one of several bleed-out tanks 22 (five shown here). These tanks are primarily storage tank for the fish awaiting onward transport, but the prolonged time the fish will be kept in these tanks will also ensure that the fish is being virtually completely drained of blood. The storage tanks are isolated and ice slurry or RSW (Refrigerated Sea Water) is circulated through the tanks. The temperature of the ice slurry or RSW is preferably about -1 to 3°C.

[0032] The transfer from the bleeding container 21 to the bleed-out tanks 22 can be done by a screw conveyor or similar.

[0033] The bleed-out tanks may be supplied with slurry ice from a slurry ice maker 23 that makes slurry ice from seawater. The seawater is conveniently treated with UV-light, ozone or other known techniques to remove bacteria or other unwanted organisms. There is conveniently a continuous circulation of water and slurry ice through the bleed-out tanks.

[0034] When a sufficient retention time of the fish in a bleed-out tank 22 has been reached, the fish in the tank may be transferred to a waiting boat for transport, or directly to a nearby processing facility. This is done by opening a valve 24 into a manifold 25 that connects the outlets of all bleed-out tanks 22 and pump the fish and ice slurry of the bleed-out tanks 22 through an outlet line 26 that connects with the pipe 7 downstream of the tank 8. The fish and ice slurry are then conveyed through the pump 13 and into the line 17, extending to a boat or to an onshore facility. On board the boat or in the onshore facility, the fish will be packaged for transport or further processed, such as filleting.

[0035] The process arrangement described above can be used in different modes. Some of these will now be described.

[0036] In a first mode all fish that is pumped into the arrangement. This may, e.g., be in a situation when all fish in a pen must be slaughtered, such as if a high concentration of algae in the water pose an immediate threat to the fish.

[0037] In that case the sorting unit is adjusted, such as by moving rollers close together, so that no fish can escape into the small fish pipe 4.

[0038] The brine tank 8 will be filled with brine having an ultra-low temperature that will stun the fish. After stunning the fish will be conveyed through the pump 13 and the cut line 18, through the separator 19 to the cutting table 21 . The residing time in the ultra-low temperature brine can be adjusted by adjusting the pump rate of the pump 13.

[0039] After cutting and initial bleeding, the fish is transferred to one or more bleedout tanks 22 for bleed-out and temporary storage.

[0040] When a boat arrives to receive and transport the fish to a destination, the valves 24 of the tanks 22 containing fish are opened one by one, so that the tanks 22 can be emptied one by one by pumping fish into the manifold 25, via the outlet line 26 and the pump 13 to the line 17.

[0041] In a second mode the task is to cut the larger fish but delouse the smaller fish and return this to the pen.

[0042] The sorting unit is the adjusted to let fish below a certain size through to the small fish pipe 4. The debusing station is conveniently placed downstream of the sorting so that the small fish can be debused before being conveyed through the small fish pump 5. The small fish is then let out into the pen through the exit pipe 6.

[0043] At the same time, the large fish is pumped into the tank 8 where it is stunned by the ultra-low temperature and onwards as described for the first mode.

[0044] In a third mode it is desired to return all the fish to the pen. This may be the case if the fish is to go through debusing, tagging, counting or other types of processes that do not involve killing the fish. In this mode, the fish may still be sorted by size.

[0045] The sorting unit 3 will be adjusted to let smaller fish into the small fish pipe 4 and the larger into the large fish pipe 7. Debusing is done downstream of the sorting.

[0046] In this case the tank 8 is not filled with water not having an ultra-low temperature. It may be filled with seawater having the same temperature as the water in the pen. It may also be filled with lukewarm water, i.e. 25-30°C, that acts to weaken the lice.

[0047] The small fish is transported through the pump 5 into the first exit pipe 6 as described above, while the large fish is transported through the pump 13 to the second exit pipe 16. The two exit pipes conveniently end in two separate pens, so that the large and the small fish can be kept separately.

[0048] If sorting of the fish is not needed, the sorting unit 3 can be adjusted either to let all fish into the small fish pipe 4 or into the large fish pipe 6.

[0049] Except for the cases when the large fish is let out again into the pen, the system handles the live and the cut fish in separate parts of the system. The small fish pipe 4, the small fish pump and the fist exit pipe 6 are never used for transporting cut fish. This means that the risk of infecting the live fish from the blood of the cut fish, and hence the need for thorough cleaning of these parts, is greatly reduced.

[0050] The system of the invention also meets the requirements of the Norwegian Food Safety Authority that sorting and cutting of fish must be done separately without any risk of contamination.

Claims (12)

PATENT CLAIMS

1. A fish stunning and bleeding arrangement, comprising a process line having an intake (1 ) into which live fish is fed, a sorting station (3) downstream of said intake (1 ), said sorting station (3) having at least two outlets (4, 7), of which at least a first outlet (7) is capable of being coupled to a stunning tank (8) capable of containing a liquid at an ultra-low temperature, said ultra-low temperature is preferably -18 °C or lower, a stunned fish pump (13) downstream of said stunning tank, a separator (19) downstream of said stunned fish pump (13), and a cutting station (21 ) downstream of said separator (19), said separator (19) separating said liquid from said fish; a recirculating unit (12) returning said liquid from said separator to said stunning tank (8), wherein a second outlet from said sorting station (4) is coupled to a live fish pump (5), said live fish pump (5) having an outlet coupled to a pen or tank for keeping live fish.

2. The arrangement of claim 1 , wherein said cutting station is coupled to at least one bleed-out tank (22), said bleed-out tank (22) receiving said cut fish and being capable of storing said fish during bleed-out and any waiting time for further transport.

3. The arrangement of any of the preceding claims, wherein a flow selector (14) is arranged downstream of said stunned fish pump (13).

4. The arrangement of claim 3, wherein an outlet of said flow selector (14) is coupled to a line (16) having an outlet to a pen or tank for keeping live fish.

5. The arrangement of claim 4, wherein an outlet of said flow selector (14) having an outlet (17) to a receiving boat or processing plant.

6. The arrangement of any of the preceding claims, wherein said at least one bleed-out tank (22) having an outlet (24) coupled to said process line between said stunning tank (8) and said stunned fish pump (13).

7. The arrangement of any of the preceding claims, wherein said stunning tank (8) having a pipe therethrough, said pipe being at least partially perforated (9) within said tank, said perforations (9) preventing fish from escaping therethrough, but allowing said liquid in said tank (8) to flow therethrough.

8. The arrangement of any of the preceding claims, wherein a brine mixer (10) is coupled to said stunning tank (8) to supply said tank (8) with fresh brine to replace brine lost during circulation.

9. A method for stunning and bleeding fish, wherein live fish is pumped from a pen or tank to a sorting station (3), said sorting station (3) sorting said fish at least into a stunning liquid at an ultra-low temperature, said ultra-low temperature is preferably -18 °C or lower, said stunned fish being transported in said stunning liquid to a separator (19), where said stunning liquid is separated from said fish, said fish being cut downstream of said separator and transferred to at least one bleed-out tank (22), while said stunning liquid is returned to join new fish to be stunned upstream of said separator (19).

10. The method of claim 9, wherein said fish and said stunning liquid pass through a pump (13) together.

11. The method of claim 10, wherein said pump (13) can selectively be operated in the following modes:

a. pumping fish in stunning liquid between the sorting station (3) and the separator (19),

b. pumping fish in ambient water between the sorting station (3) and an exit line (17), and

c. pumping fish between a bleed-out tank (22) and a boat or further processing plant.

12. The method of any of the preceding claims 9-11 , wherein the sorting station also sorts fish that is determined to be returned to the pen into a live fish line (4) extending through a second pump to a second exit line (6).