WO2015043603A1

WO2015043603A1 - System and method for removal of parasites on fish

Info

Publication number: WO2015043603A1
Application number: PCT/DK2014/050300
Authority: WO
Inventors: Erhard Joensen
Original assignee: Erhard Joensen
Priority date: 2013-09-30
Filing date: 2014-09-24
Publication date: 2015-04-02
Also published as: DK177873B1

Abstract

The present invention concerns a system and a method for removing fish parasites (4), the system including a pump system (14) pumping fishes (8) from a first volume (6) to a second volume (10), wherein the system is provided with a number of nozzles (16) directing water jets towards the fishes. It is the object of the invention to remove fish parasites in an efficient, rapid and gentle way. This can be achieved with at least one suction tube (20) through which a first water current is sucked upwards together with fish from the first fish volume (6), the suction tube provided with a number of nozzles (16) directing at least partially transverse water jets (18) against fish passing through the suction tube, wherein the pump system delivers substantially parasite-free fishes (12) into the second fish volume (10). In this way it can be achieved that simultaneously with the fishes being cleaned from parasites the fishes are moved from a first volume assumed to contain relatively many fishes encumbered with parasites. These fishes will, after removal of parasites, be transferred into a second fish volume that is expected to contain a very limited number of parasites.

Description

SYSTEM AND METHOD FOR REMOVAL OF PARASITES ON FISH

Field of the Invention

The present invention concerns a system and a method for removing fish parasites, the system including at least one defined first water-filled fish volume, the first fish volume containing fish with parasites, the system including at least one defined second water-filled fish volume, the second fish volume containing largely parasite- free fishes, the system including a pump system that pumps fish from the first volume to the second volume, the system arranged with a number of nozzles directing water jets towards the fishes. Background of the Invention

WO 9824304 describes a method for removing parasites from fish, especially removal of sea lice. In connection with a narrow flow channel in which a liquid is flowing, the fish is impacted when passing a liquid flow generated by various nozzles directed towards the fishes. All these nozzles are connected to a water pump. Formation of transverse water flows against the body of the fish will remove most of the parasites adhering to the fish, including sea lice. WO 9824304 thus describes that the fishes are conveyed downwards through a flow channel while the fishes are impacted by water jets from a transverse direction on their way down. This means that the fishes are subjected to a gradually increasing ambient pressure during passage of the tube. Object of the Invention

It is the object of the invention to remove fish parasites in an efficient, rapid and gentle way. A second object of the invention is to avoid the use of chemicals for combating fish parasites. A third object is removal of parasites performed by transfer from a first fish volume to a second fish volume. Description of the Invention

The objects can be achieved by a system as described in the introduction which is modified such that the pump system is provided with at least one suction tube through which a first water current is sucked upwards together with fish from the first fish volume, the suction tube provided with a number of nozzles directing at least partially transverse water jets against fish passing through the suction tube, wherein the pump system delivers substantially parasite-free fishes into the second fish volume. In this way it can be achieved that simultaneously with the fishes being cleaned from parasites the fishes are moved from a first volume assumed to contain relatively many fishes encumbered with parasites. These fishes will, after removal of parasites, be transferred to a second fish volume that is expected to contain a very limited number of parasites. In that way removal of parasites on fish is effected in a very efficient way without applying toxic chemicals or peroxide or any other chemical means that are a hazard for fishes. As removal of parasites occurs in connection with an otherwise possibly necessary transfer of fish from one fish volume to another, which even may be required in beforehand, the energy consumption by this invention will be minimal. Additional consumption of energy is limited to pumps for driving the water flows directed towards the fishes from a transverse direction. The completely chemical-free cleaning of parasites, such as e.g. sea lice, can be very important for the well-being of salmon in any sea fish farm. The use of chemicals has appeared to be very disadvantageous in connection with the rearing of salmon as the sea lice within a very short span of years become resistant to the types of toxic substances used. The entire salmon industry has therefore been forced to switch to peroxide for removal of sea lice. Peroxide is, however, so dangerous for the fishes that a certain percentage of salmon dying by this process must be taken into account. The present invention therefore solves the substantial problem appearing in fish farms in fresh water or at sea where the fishes are so densely reared that the number of parasites on individual fishes rises significantly.

By an alternative embodiment of the invention, the nozzles of the suction tube can be provided in connection with the inlet of the pump system. Hereby is achieved that the nozzles are disposed in an area of the suction tube where the ambient pressure is relatively low. Hereby it can be utilised that many parasites, including sea lice, use a suction cup principle for attaching to the scales of the fishes. By reducing the ambient pressure within a tube with a flowing liquid there will be achieved a reduction of the retention force exhibited by the parasites. Particularly sea lice appear to almost lose their retention force when the pressure around the fish is slightly changed. If the fish is simultaneously impacted by transverse water flows, the sea lice may easily be flushed off the fish as they will only have a weak retention force left. The same goes probably for many other fish parasites. By a further alternative embodiment of the invention, the system may contain at least one filter for collecting parasites, wherein water returning from the first water current runs through the filter after passing the pump system and before returning to a surrounding watercourse. By removing the sea lice from the return water from the process itself it is avoided that the sea lice just repeat their previous behaviour, as the return water is probably discharged in the vicinity of e.g. the salmon cages in which the salmon are kept anyway. The sea lice will just select other salmon, and the process can in principle be restarted. Therefore it is necessary that the sea lice are removed from the return water, and this is feasible by means of filtering. The sea lice can then be disposed of like any other biological waste. The dead sea lice can possibly be used directly as feed.

By a further alternative embodiment of the invention, the suction tube can include at least one narrowing of the cross-section of the suction tube, forming a venturi means, the venturi means including nozzles that generate at least partially transverse water flows directed towards fish passing through the venturi means. By designing the suction tube with a narrowing, a venturi effect is achieved as the flow rate of the water will be increased through the venturi means, thereby causing a lower ambient pressure. A better effect can therefore be achieved if a venturi means is found close to the inlet of a pump system. However, a change of the ambient pressure is to be kept at a level such that the fish which has a swimming bladder, is not unnecessarily stressed by a sudden pressure drop. The venturi system is thus to be designed such that the reduction in pressure is probably a few millibars only. By a further alternative embodiment of the invention, the suction tube may contain several venturi narrowings provided with nozzles for establishing transverse water flows. By providing the suction tube with several venturi means with nozzles, fish may in principle go through several treatment steps in immediate succession while the fishes pass a suction tube where the fishes are to be sucked up for transport from one fish volume to another. By performing a treatment several times, the greater part of various parasites that suck on to fish can probably be removed. Even tenacious sea lice will be stressed by the repeated treatment and almost automatically let go, after which the transverse water jets remove the sea lice from the salmon, and because of the rapid flow present in the suction tube, the sea lice will not have a good chance of attaching again by sucking before the salmon has been removed from the water current and returned to the other fish volume. By repeated treatment there may probably be effected a 100% removal of parasites. The invention also concerns a method for complete or partial removal of parasites from fish by means of a system as described above, wherein the method at least includes the following steps in sequence: a: establishing a first water current through at least one suction tube from a first fish volume through a pump system; b: reducing ambient pressure of the water in the suction tube; c: establishing transversely directed water jets in the suction tube by means of nozzles; d: separating parasite-free fishes from the established first water current; e: moving separated fishes to a second fish volume; f: filtering the first water current for separating parasites.

The method can be performed if using a fish pump, e.g. made by Inventive Marine Products under the name CanaVac. This pump is typically to be driven by a Samson ring pump which can be regarded as a commonly known vacuum pump. It is possible hereby to suck up fish from relatively great depth and move the fishes through e.g. one or more venturi means such that transverse water flows remove the greater part of the parasites on the fishes. By conducting the sucked up water back through a filter for removing the parasites and transferring the fishes to another fish volume where the majority of the parasites have been removed, the greater part of the parasites are removed before the fishes go into the other volume. By means of the invention it is thus possible to remove most of the parasites, including sea lice, in a very gentle way without using chemicals. By using the CanaVac fish pump transport of fish through the system can be effected in a very gentle and humane way where damage on fishes largely does not occur. If the invention is applied at the point where the fishes are anyway to be moved from one fish volume to another, removal of parasites including sea lice can be performed with a very low energy consumption as the only other challenge that arises is generation of sufficient water pressure for generating transverse flow through the nozzles. A substantially cheaper and at the same time more efficient removal of parasites than by traditional methods using peroxide is hereby achieved.

Since removal of parasites occurs in an upward flow from a fish volume, there will be a falling ambient pressure in the suction tube, which can be further amplified by using a venturi means whereby all parasites attached to fishes by suction cup action have their retention force reduced, or the retention force is completely neutralised. Parasites will normally be able to adapt their suction capability concurrently with the fish changing its level in water, but by the relatively rapid pressure change the parasites cannot increase their suction capability and will thereby almost fall off without further treatment. By the present invention there will occur an almost 100% removal of parasites.

In the future, alternative embodiments can be envisaged where e.g. fishes are sucked up from the first fish volume and delivered into the same volume after cleaning, and with a pump system that runs more or less continuously in connection with large sea fish farms. It may even be possible to learn fish when encumbered by sea lice to seek into the pump system by themselves.

Description of the Drawing

Fig. 1 shows a schematic drawing of the invention.

Fig. 2 shows a first alternative embodiment of the invention.

Fig. 3 shows a second alternative embodiment of the invention.

Fig. 4 shows a third alternative embodiment.

Detailed Description of Embodiments of the Invention

Fig. 1 shows a schematic drawing of the invention. On Fig. 1 is shown part of a system 2 for removing parasites on fish 8. Parasites 4 sitting on fish 8 and partly removed from fish 8 are shown in a first fish volume 6. Fish 8 are sucked upwards through a suction tube 20 where a strong water current 22 is present. The water current 22 is produced by a pump 14, 172 (Fig 2,3,4). Fish 12 from which parasites have been cleaned are guided back to a fish volume 10 after nozzles 16 have directed water jets 18 towards the fishes 8, 12 while they pass the nozzles 16.

When fishes 8 sucked up through the suction tube 20 by means of a water current 22, a pressure drop occurs up through the tube, among others due to the flow rate such that the fishes 8 experience a reduced ambient pressure. The reduced pressure means that parasites 4, including sea lice retained on to the fishes 8 by suction cup action, have their retentive force reduced considerably and possibly completely neutralised. The water jets 18 can thereby relatively simply remove parasites 4 including sea lice when in connection with reduced ambient pressure there is simultaneously provided a water jet 18 coming from a different direction than the immediately surrounding water. Partial turbulence will thus arise around the fishes 8, and this turbulence removes the parasites 4 including sea lice from the fishes 8 such that the parasites 4 will not be able to suck onto the fish 8 again. Afterwards, the fishes 8 encounter a filter (162; Fig. 4), e.g. in the form of a soft rubber net where water together with parasites 4 are sucked through, whereas the fishes 8 are forced into a downward going pipe system where the now parasite-free fishes 12 are subsequently moved to fish volume 10. Fig. 2 shows a first alternative embodiment of the invention where only part of the suction tube 20 is shown, and where this suction tube 20 is finished with a schematic pump unit 14. A water current 22 flows in the tube 20 together with a shown fish 8. The fish 8 has parasites 4 where the tube 20 is designed with a venturi means 28 with the nozzles 16 provided in connection with the venturi means.

Because of the venturi means 28, the flow rate of the through-flowing water 22 is increased when passing the venturi 28, whereby a pressure drop occurs in the flowing water 22, the pressure drop contributing to reducing or totally neutralising the retentive force of the parasites 4 that are attached by suction cup action on the fish 8. The water jets 18 will then flush the parasites 4 away from the fish 8. The strong water current 22 providing further turbulence together with the water jets 18 means that the parasites 4 will have difficulty in getting in contact with the fish 8 in the very turbulent water so that parasites 4 and fish 8 after passing the venturi are conducted to the pump unit 14 where separation of fishes 8 and parasites 4 occurs. Separation can be effected in very different ways; the fishes can e.g. pass a ring pump where the fishes 8 bypass a pump wheel due to a liquid ring around the pump that may be passed by the fishes. A separation will thus occur after the pump, where the fishes 8 are guided to another fish volume 10 whereas the greater part of the pumped water together with the parasites 4 are conducted through a filtering unit before the water is returned.

Fig. 3 shows a second alternative embodiment of the invention. A first fish volume 6 contains fish 8, and in this fish volume is provided a tube 20 which via a pump unit 14 sucks fish up through the tube 20. The tube 20 is designed with several venturi means 28. The venturi means 28 are designed with nozzles 16 generating water flows 18 directed towards fish 8 passing through the venturi means 28. The lowermost fish shown on Fig. 3 indicates that this fish has a number of parasites 4 attached to the body of the fish 8.

For fishes 8 with parasites 4 passing through a plurality of venturi means 28 where a transverse flow of water through nozzles 6 occurs at the same time, reduction of ambient pressure in the venturi means 28 will entail that the parasites 4 completely or partially lose there retention force as the greater part of the parasites 4 are attached to the fish by suction cup action. Negative pressure under the suction cup means that the parasite 4 is provided a retention force on the fish. If the pressure outside the suction cup of the parasite 4 is reduced, the retention force is reduced as well as an approximate pressure equalisation between the low pressure inside the suction cup and the low pressure in the surroundings caused by the rapid current through the venturi means 28. Repeated treatments with more and more reduced pressure up through the tube 20 will probably mean a total removal of parasites 4.

Fig. 4 shows a third alternative embodiment 102 where reference numbers from above are raised by 100, whereas new reference numbers continue. Fig. 4 shows a first fish volume 106 containing fishes 108 which may be infested with parasites, e.g. sea lice (not shown on Fig. 4). The Figure also shows a second fish volume 110 containing fish 112 which are cleaned from parasites. A suction tube 120 is designed with a number of nozzles 116 spraying a transverse water flow into the suction tube 120. The suction tube 120 is designed with several venturi means 128. The suction tube 120 is connected with a transverse line 130 going to a pump 132. This pump generates water flows in the tube 134 which via ring-shaped connecting tubes 136 communicate with nozzles 116. The suction tube 120 continues in a tube connection 138 which through a valve 140 communicates with a tank 142. The tank is provided with a discharge valve 144. There is also provided a return valve 146 connected with a pipeline 148. The tube 138 is also connected with a valve 150 communicating further with a tank 152. The tank 152 is provided with a valve 154, and the tank 152 is also provided with a discharge valve 156. A pipeline 158 is combined with the pipeline 148 into a common pipeline 160. The pipeline 160 is extended to a fish separator 162. A pipeline 164 continues from the fish separator 162 to the second fish volume 110. Water is conducted from the fish separator 162 through the pipeline 165 to a separating unit 166. Clean water is conducted from the separating unit 166 through the pipeline 168 to surrounding water. The separating unit 166 comprises an inclining filter where the parasites 4 are separated and collected in a volume 167.

The suction tube 120 sucks up fish from the first fish volume 106. These fishes are subjected to strong transverse water jets from the nozzles 116 when passing through the venturi means 128. A pressure drop takes place in the tube 120 by means of the pump 132. This first reduction in pressure provides that parasites such as sea lice are reduced in retention force to the fishes, as attachment to the fishes occurs by suction cup action. Falling ambient pressure will mean that the parasites partially lose their retention force already when passing the branch 130. Additional pressure drops occur by passage of the venturi means 128 where transverse water flows from the nozzle 116 cause whirling and a kind of turbulence around the fishes whereby the parasites are pulled off the surfaces of the fishes. The nozzles 116 may advantageously be directed obliquely downwards towards the fishes, whereby the water current, which is flowing continually upwards, is directly more accurately towards the venturi means where the ambient pressure is the lowest. The nozzles 116 may correspondingly be turned such that a rotating movement of the water flow in the tube 120 is performed. Water and fish are alternatingly pumped through the tube 138 into the two tanks 142 and 152. By means of the valves 140, 146 and 144 a total regulation of the volume 142 is performed. If valve 144 is open simultaneously with valve 140, vacuum pump 172 will perform filling of the volume 142 via the line 170. At the same time, the volume 152 will have valve 156 open such that this tank is simultaneously emptied of water and fish. When the tank 142 is full, a switching is performed, and the process occurs oppositely from the second tank. Use of a double chamber system means that vacuum pump 172 can run continuously. A simple level control by means of floats can determine the time for switching between the tanks 142 and 152. Water and fish leave the tanks through pipe connection 158 and pass fish separator 162 via pipe connection 160. The fish separator is an array of rubber lamellae where the fishes briefly leave the water as the water passes through the rubber lamellae and down into the pipeline 165. The fishes continue down through the pipeline 164 where the fishes again encounter a water current such that the fishes are only briefly above the water. The pipeline 165 continues through a parasite separator 166 which is designed with a filter such that water passes through the filter while the parasites are filtered off. The parasites are collected in the volume 167 from which they can be disposed of.

By means of this invention there may thus occur a moving of fishes from a first fish volume 106 to a second fish volume 110, and at the same time a total cleaning of parasites from the fishes can be effected.

Claims

1. A system (2) for removing fish parasites (4), the system (2) including at least one defined first water-filled fish volume (6), the first fish volume (6) containing fish (8) with parasites (4), the system (2) including at least one defined second water-filled fish volume (10), the second fish volume (10) containing largely parasite-free fishes (12), the system including a pump system (14) that pumps fish (8) from the first volume (4) to the second volume (10), the system (2) arranged with a number of nozzles (16) directing water jets (18) towards the fishes (8), characterised in that the pump system (14) is provided with at least one suction tube (20) through which a first water current (22) is sucked upwards together with fishes (8) from the first fish volume (6), the suction tube (20) provided with a number of nozzles (16) directing at least partially transverse water jets (18) against fish (8) passing through the suction tube (20), wherein the pump system (14) delivers substantially parasite-free fishes (12) into the second fish volume (10).

2. System according to claim 1, characterised in that the nozzles (16) of the suction tube (20) is provided in connection with the inlet (130) of the pump system (132).

3. System according to claim 1 or 2, characterised in that the system (2) contains at least one filter (162) for collecting parasites (4), wherein water returning from the first water current (22) runs through the filter (162) after passing the pump system (14) and before returning to a surrounding watercourse.

4. System according to one of claims 1-3, characterised in that the suction tube includes at least one narrowing of the cross-section of the suction tube, forming a venturi means (28), the venturi means (28) including nozzles (16) that generate at least partially transverse water jets (18) directed towards fishes passing through the venturi means (28).

5. System according to one of claims 1-4, characterised in that the suction tube contains a plurality of venturi means (28), the venturi means (28) provided with nozzles (16) for establishing transversely directed water jets (18).

6. A method for complete or partial removal of parasites (4) from fish (8) by means of a system (2) according to any of claims 1-5, the method including the following steps in sequence:

a: establishing a first water current (22) through at least one suction tube (20) from a first fish volume (6) through a pump system (14);

b: reducing ambient pressure of the water in the suction tube (20);

c: establishing transversely directed water jets (18) in the suction tube (20) by means of nozzles (16);

d: separating parasite-free fishes (12) from the established first water current (22); e: filtering the first water current (22) for separating parasites (4);

f: moving separated fishes (12) to a second fish volume (10).