GB2557993A

GB2557993A - Apparatus for the removal of fish lice

Info

Publication number: GB2557993A
Application number: GB1621885.1A
Authority: GB
Inventors: David Duncan Edwin; John Kinsey Andrew
Original assignee: Mohn Tech Ltd
Current assignee: Mohn Tech Ltd
Priority date: 2016-12-21
Filing date: 2016-12-21
Publication date: 2018-07-04
Also published as: GB201621885D0

Abstract

An apparatus 10, for the removal of parasites from the body of a fish 100, comprising: a treatment station 12; biasing means adapted to bias the fish towards the treatment station; and a delivery device, such as nozzle 34 powered by pump 30, adapted to deliver a high velocity flow of a medium. The medium may be water with additives such as pharmaceuticals, air or sand. The biasing means may be conduit 20 with inlet 22 and outlet 24, and propeller 50 to act as flow generating means. There may be optionally a fish detector, parasite counting device and/or feed dispenser. The conduit may be orientated horizontally or vertically [figure 3]. Also disclosed is a method of using the apparatus.

Description

(54) Title of the Invention: Apparatus for the removal offish lice

Abstract Title: Apparatus for removing parasites from fish with high velocity flow of a medium.

(57) An apparatus 10, for the removal of parasites from the body of a fish 100, comprising: a treatment station 12; biasing means adapted to bias the fish towards the treatment station; and a delivery device, such as nozzle 34 powered by pump 30, adapted to deliver a high velocity flow of a medium. The medium may be water with additives such as pharmaceuticals, air or sand. The biasing means may be conduit 20 with inlet 22 and outlet 24, and propeller 50 to act as flow generating means. There may be optionally a fish detector, parasite counting device and/ or feed dispenser. The conduit may be orientated horizontally or vertically [figure 3], Also disclosed is a method of using the apparatus.

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Apparatus for the Removal of Fish Lice

The present invention relates to the removal of parasites from the bodies of fish. In particular, but not exclusively, the present invention relates to the removal of sea lice from the bodies of fish.

Damage to fish stocks in salmon farms due to sea lice is a serious issue given the high densities of fish in relatively small net-cages. Sea lice attach themselves to the skin, fins and/or gills of fish and feed off the mucous or skin. This feeding activity can cause serious fin damage, skin erosion, constant bleeding, and deep open wounds creating a pathway for other pathogens. Just a couple of lice on a juvenile salmon or a large number of lice on a mature salmon can be fatal. It is also possible for sea lice to carry diseases between farmed and wild salmon. It has been estimated that sea lice cause around EUR 300 million per year in damage to the industry worldwide as a result of reduced fish growth, higher mortality and treatment costs.

All known methods of treatment for the removal of the lice are limited or have inherent disadvantages. Organophosphates were considered the most effective treatment. However, for environmental reasons, its use in salmon farming is now banned in many countries including the UK. Various other drug treatments have been used but lice become increasingly resistant to the treatment. The use of hydrogen peroxide is growing. However, one recent study found that this can compromise the health of treated fish.

It is also known to use a thermolicer, a device which applies a sudden change of temperature to water, to which the lice have a low tolerance and so can be killed and removed from the fish. However, the temperature change is uncomfortable for the fish (and in some cases can be fatal), and thermolicer devices are expensive.

It is desirable to provide improved methods of treatment for the removal of the lice. It is desirable to provide non-chemical or non-pharmaceutical methods of treatment for the removal of the lice. It is desirable to provide methods of treatment for the removal of the lice which treat the fish in a permanent manner from early life and without removing them from their natural environment.

It is known to utilise a device called an air knife in various manufacturing operations.

For example, they can be used to blow off liquid or debris from products as they travel on conveyors, control the thickness of liquids, dry liquid coatings, or cool product surfaces. The air knife provides a high-intensity, uniform sheet of laminar airflow.

It is also known to use pressure washers to remove mould, dust, dirt and the like from surfaces. A motor drives a high-pressure water pump, and the nozzle design helps to create a flow of water at high pressure and velocity. The nozzle has a particular spray angle or nozzle angle which sets the angle at which the water leaves the nozzle. The pressure rating of the pump, nozzle diameter and nozzle angle determine the force received at the sprayed object.

According to a first aspect of the present invention there is provided an apparatus for the removal of parasites from the body of a fish, the apparatus comprising:

a treatment station;

biasing means adapted to bias the fish towards the treatment station; and a delivery device adapted to deliver a high velocity flow of a medium at the treatment station.

Optionally, the medium comprises water. Optionally, the delivery device includes a high pressure pump. The medium may include one or more additives such as chemical or pharmaceutical agents.

Alternatively, the medium may comprise particles such as sand. Alternatively, the medium may comprise air.

Optionally, the delivery device is adapted to provide a uniform sheet of laminar medium flow. Optionally, the delivery device includes a first nozzle adapted to provide a uniform sheet of laminar medium flow. Optionally, the first nozzle is adapted to provide a wide spray angle.

Optionally, the delivery device includes a second nozzle and wherein a nozzle is provided at each lateral side of the treatment station for treating each side of the body of the fish.

The delivery device may include a third or more nozzles and wherein the nozzles are provided in an annular arrangement for delivering the medium in multiple directions.

Optionally, the delivery device is adapted to deliver the flow from the first and second nozzles simultaneously. This helps to stabilise the fish during treatment.

The biasing means may define a direction which is downstream towards the treatment station and an opposite direction which is upstream away from the treatment station.

Optionally, the delivery device is adapted to deliver the flow of water in the upstream direction. Optionally, the delivery device is adapted to deliver the flow of water at an oblique angle relative to the upstream direction.

Optionally, the delivery device is adapted to commence the flow prior to the fish arriving at the treatment station. This can be used to temporarily slow or halt the fish at the treatment station.

The apparatus may include a plurality of treatment stations. The plurality of treatment stations may be cascaded or arranged in a series in the downstream direction for delivering a sequence of treatments to the fish. The treatments of the sequence of treatments may vary in terms of one or more of flow pressure, velocity, the oblique angle of spray and the nozzle spray angle.

Optionally, the biasing means comprises a conduit having an inlet which the fish can enter and an outlet provided at or near the treatment station. Optionally, the inlet has a diameter which is greater than the diameter of the outlet. Optionally, the treatment station is located along a central axis defined by the conduit. At least a portion of the conduit may be tapered or step down in width for funnelling the fish towards the treatment station.

Optionally, the biasing means has a frame structure. Optionally, the biasing means comprises a cage or netting. Optionally, the conduit comprises a cage or netting.

Optionally, the biasing means includes means for generating a flow through the conduit. Optionally, the flow generating means is adapted to generate a flow in the downstream direction.

Optionally, the flow generating means comprises an impellor provided near the inlet. The generated flow encourages the fish to enter the conduit. At higher flow rates, the fish can be entrained in the flow.

Optionally, the flow generating means is adapted to generate a flow at a flow rate which is predetermined to stabilise the fish during treatment. The flow generating means may be adapted to generate a flow at a flow rate which is predetermined to prolong the fish’s presence at the treatment station to allow a longer treatment time.

In one or more embodiments, the conduit may have a closed wall and be shaped to modify the generated flow through the conduit.

The conduit may be shaped to increase the flow rate of the generated flow in at least one section of the conduit. The conduit may include a constriction at the section of the conduit for producing an increased flow rate at the constriction using the Venturi effect. The treatment station may be located at or near the constriction.

In another or more embodiments, the conduit may be shaped to decrease the flow rate of the generated flow in at least one section of the conduit. The conduit may include an expanded portion at the section of the conduit for producing a decreased flow rate at the expanded portion. The treatment station may be located at or near the expanded portion.

According to a first embodiment of the invention, the downstream and upstream directions are horizontal directions, and the biasing means is horizontally orientated. The inlet and the outlet may be vertically orientated. The flow generating means may be adapted to generate a flow in a horizontal direction.

According to a second embodiment of the invention, the downstream and upstream directions are vertical directions and the biasing means is vertically orientated. The inlet and the outlet may be horizontally orientated. The flow generating means may be adapted to generate a flow in a vertical direction.

According to the second embodiment, optionally, the apparatus includes a buoyant member provided at the surface of the water. Optionally, the buoyant member comprises an inflatable ring or a rigid air filled ring. The buoyant member may be dimensioned to allow a typical jumping fish to clear the buoyant member.

According to the second embodiment, optionally, the conduit comprises a ramp which slopes downwards from the buoyant member to the outlet which is provided at a depth below the buoyant member. The upper surface of the ramp may define the inlet.

According to the second embodiment, at least one of the flow generating means and the biasing means may be adapted to generate a whirlpool or vortex effect. The ramp may include spiral grooves to assist generating the whirlpool or vortex effect. The encourages the fish to move towards the centre of the inlet and/or to travel downwards to the treatment station.

According to the second embodiment, the outer boundary of the inlet may substantially correspond to an inner boundary defined by the buoyant member. Alternatively, a plurality of apparatus may be provided within the inner boundary defined by the buoyant member. The plurality of apparatus may be arranged in an array. The profile of the ramp may be dimpled. The ramp may include a plurality of locally deep pockets, each pocket corresponding to the location of an apparatus.

Optionally, the apparatus includes one or more fish detectors. Optionally, a fish detector is provided at or near the treatment station. Optionally, the fish detector is connected to the delivery device which is configured to perform treatment only if a fish is detected at the treatment station.

Optionally, the apparatus includes a counting device for counting the number of parasites on the body of the fish. Optionally, the counting device comprises an imaging device connected to a processor of a computer, the imaging device or computer configured with object recognition software.

Optionally, the counting device is provided at or near the inlet of the conduit.

Optionally, the counting device is connected to the delivery device which is configured to perform treatment only if the counted number of parasites is greater than a predetermined number.

Optionally, the apparatus includes imaging means for capturing an image of the fish before and after treatment.

The apparatus may include at least one fish feed dispenser. A dispenser may be located 20 at or near the inlet for encouraging fish to enter the inlet. Alternatively, or in addition, a dispenser may be located at or near the treatment station for encouraging fish to pause at the treatment station.

According to a second aspect of the present invention there is provided a method of 25 removing parasites from the body of a fish, the method comprising the steps of:

providing a treatment station;

biasing the fish towards the treatment station; and delivering a high velocity flow of a medium at the body of the fish when it is at the treatment station.

Optionally, the medium is water.

Optionally the medium is extracted from the body of water in which the fish is present.

Optionally, the medium is delivered using a delivery device adapted to provide a uniform sheet of laminar medium flow.

Optionally, the method includes delivering the medium simultaneously to each lateral side of the body of the fish.

The method may include delivering the flow of water in the upstream direction.

Optionally, the method includes delivering the flow of water at an oblique angle relative to the upstream direction.

The method may include commencing the flow of the medium prior to the fish arriving at the treatment station.

Optionally, the biasing means comprises a conduit having an inlet which the fish can enter and an outlet provided at or near the treatment station. Optionally, the biasing means has a frame structure.

Optionally, the method includes generating a flow through the conduit. Optionally, the method includes generating the flow at a sufficient flow rate to entrain the fish in the flow. Optionally, the method includes generating the flow at a flow rate which is predetermined to stabilise the fish during treatment. Optionally, the method includes generating a flow at a flow rate which is predetermined to prolong the fish’s presence at the treatment station to allow a longer treatment time.

Optionally, the method includes shaping the conduit to modify the generated flow through the conduit. The conduit may be shaped to increase the flow rate of the generated flow in at least one section of the conduit. Alternatively, or in addition, the conduit may be shaped to decrease the flow rate of the generated flow in at least one section of the conduit.

According to a first embodiment of the invention, the downstream and upstream directions are horizontal directions and the method includes biasing the fish in a horizontal direction.

According to a second embodiment of the invention, the downstream and upstream directions are vertical directions and the method includes biasing the fish in a vertical direction.

According to the second embodiment, the inlet may be provided at the surface of the water. A buoyant member may circumscribe the inlet. The conduit comprises a ramp which slopes downwards from the buoyant member to the outlet.

According to the second embodiment, the method may include generating a whirlpool or vortex effect.

According to the second embodiment, the outer boundary of the inlet may substantially correspond to an inner boundary defined by the buoyant member.

Alternatively, the method may include providing a plurality of apparatus within the inner boundary defined by the buoyant member. The plurality of apparatus may be arranged in an array.

The profile of the ramp may be dimpled. The ramp may include a plurality of locally deep pockets, each pocket corresponding to the location of an apparatus.

The method may include detecting the presence of a fish at or near the treatment station and performing treatment only if a fish is located at the treatment station.

The method may include determining the velocity of the fish as it approaches the treatment station and responsively adjusting at least one of the angle, pressure and timing of the flow delivered by the delivery device.

The method may include counting the number of parasites on the body of the fish and performing treatment only if the counted number of parasites is greater than a predetermined number.

The invention will be described below, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a sectional side view of an apparatus according to a first embodiment of the invention;

Figure 2 is a plan view of the apparatus of Figure 1;

Figure 3 is a sectional side view of an apparatus according to a second embodiment of the invention;

Figure 4 is a plan view of the apparatus of Figure 3; and

Figure 5 is a plan view of an apparatus according to a third embodiment of the invention.

Figures 1 and 2 show a first embodiment of an apparatus 10 for the removal of parasites from the body of a fish 100. The apparatus 10 is submerged below the surface 101 of a body of water where fish are present. The apparatus 10 comprises a treatment station 12 and biasing means which is adapted to bias the fish 100 towards the treatment station 12.

The apparatus 10 also includes a delivery device comprising a high pressure water pump 30 which pumps water via hosing 32 to two nozzles 34 located at the treatment station 12 (only one is shown in the side view of Figure 1). Although in this embodiment the pump 30 is a submerged pump located in the body of water, it could be at any remote location, such as floating on the surface of the water or situated on nearby land.

The biasing means comprises a conduit 20 which has a frame structure and comprises a cage. The conduit 20 has an inlet 22 which the fish can enter and an outlet 24. The inlet 22 has a diameter of about 1 m, which is greater than the diameter of the outlet which is about 50 cm. Between the inlet 22 and outlet 24, a portion of the conduit 20 tapers down in diameter. The treatment station 12 is located along a central axis 26 defined by the conduit 20. It is located near the outlet 24 and so at a section of the conduit 20 which has a narrow diameter. The conduit 20 therefore serves to funnel the fish 100 towards the treatment station 12. The conduit 20 may advantageously be transparent or have a fine mesh structure.

Figures 1 and 2 are not drawn to scale. In particular, the conduit 20 could have a substantially greater length than as shown in the figures. Typically, the length of the conduit in this embodiment is around 1 to 2 m.

The conduit 20 can be considered to define a downstream direction 102 which is towards the treatment station 12 and an opposite upstream direction 104 which is away from the treatment station 12. In this embodiment, the downstream and upstream directions are horizontal directions.

Figure 2 shows that water 36 is sprayed from the nozzles 34 in the upstream direction 104 but also at an oblique angle relative to the upstream direction 104. Spraying in an upstream direction 104, which is opposite to the direction of travel of the fish 100 producing a shearing force on the body of the fish 100. As shown in Figure 1, the nozzles 34 are adapted to provide a uniform sheet of laminar flow 36 which has a wide spray angle. This enhances the shearing action and has the effect of ‘scraping’ each side of the body of the fish 100 when it is at the treatment station 12. This scraping action can remove sea lice and other parasites from the fish’s body. The water spray 36 can be regarded to be a 'water blade’ scraping the body of the fish 100. It is similar to the spray from a pressure washer or the output from an air knife.

The nozzles 34 may be adapted to provide a sheet of vertical laminar flow 36. However, they may be adapted to produce an arcuate profile of laminar flow 36. This arcuate profile could be complementary to the lateral profile of the fish’s body.

Each of the flow pressure and velocity, the oblique angle of spray and the nozzle spray angle are selected to provide a scraping action which is effective in removing parasites but which causes minimal distress to the fish 100. Fish such as salmon are physically adapted and accustomed to swimming upstream in sometimes highly turbulent water. Therefore, the treatment given resembles a natural occurrence that the fish 100 may have experienced. It is therefore believed that the spraying treatment does not cause significant distress.

Salmon and many other types of farmed fish are relatively flat and have a high aspect ratio of vertical height to lateral width. Therefore, the vast majority of parasites can be found on the lateral body of these fish. The above described arrangement of nozzles is appropriate for this shape. However, it may be desirable to also treat upper and lower surfaces of the fish, or other types of fish may require a different arrangement.

In such case, two more nozzles could be used, which could be located at the top and bottom of the treatment station 12. Indeed, further nozzles could be added to provide an annular arrangement for delivering the medium in multiple directions to remove parasites from all around the fish 100.

Also, in other embodiments, the apparatus 10 could include a series of treatment stations 12 for delivering a sequence of treatments to the fish 100. The treatments of the sequence of treatments could vary in terms of their ‘harshness’ by which is meant that the treatment stations 12 could vary in the flow pressure, velocity, the oblique angle of spray or the nozzle spray angle used.

The treatment method according to the invention only uses water (sea water), which is obviously in abundant supply. However, if desired, chemicals (such as hydrogen peroxide) or pharmaceuticals could be added to the water used to spray the fish to help disinfect the wound once the parasite has been removed.

A fish detector 40 is located immediately downstream of the nozzles 34. This comprises an infrared emitter and detector (various other known sensors could be used) and sends a signal to the delivery device when the emitted beam is broken by a fish 100 travelling between the emitter and detector. In response, the delivery device commences the spray 36. If the detector 40 is carefully located, the spray 36 will not commence until the head of the fish 100 is sufficiently downstream and only the body of the fish 100 will be sprayed. The aim is to minimise distress and reduce the likelihood that the fish 100 will turn back and swim towards the inlet 22.

The water 36 is simultaneously sprayed at the same pressure and velocity, and at complementary angles, from each nozzle 34. This tends to cancel out any lateral forces produced by the flow 36 and so helps to stabilise and ‘hold’ the fish 100 during treatment.

Obviously, the fish 100 may not swim along the central axis 26 and be in the exact centre of the treatment station 12. If the fish 100 is closer to one of the nozzles, it will receive a greater force from that nozzle. However, this greater force will include a lateral force which will move the fish 100 towards the axis 26 after which the lateral forces will be in balance.

If it is desired to avoid strong spraying forces when the fish 100 is close to a nozzle, further fish detectors (not shown) could be provided for detecting the lateral position of the fish 100. The spray pressure could be reduced in proportion to the fish’s proximity to the nozzle.

Because the fish is travelling downstream and has a momentum, the upstream direction 25 104 of the spray can help to slow or halt the fish 100. This will prolong the fish’s presence at the treatment station 12 and allow a longer treatment time. If it is desired to increase this prolonging effect, the delivery device can commence the flow 36 prior to the fish 100 arriving at the treatment station 12. This can be used to temporarily slow or halt the fish 100 at the treatment station 12.

The momentum of the fish 100, and therefore what is required to slow or halt the fish

100, depends on the fish’s velocity as it swims through the conduit 20. A series of further fish detectors (not shown) can be located along the conduit 20 and the fish’s position over time can be used to determine its velocity. The delivery device can be configured to adjust the angle, pressure or timing of the flow 36. For instance, if the fish 100 is travelling at a high velocity, the spray 36 can be commenced early, perhaps at a higher pressure for maximising the upstream flow, and then at normal pressure when the fish nears the treatment station 12.

The above described biasing means could be sufficient for many types of fish. However, further biasing means could be used if required. This could be means for generating a downstream flow through the conduit 20 to encourage the fish 100 to travel in this direction.

The flow generating means comprises an impellor 50 provided upstream of the inlet 22. A guard cage (not shown) protects the fish from being harmed by the rotating impellor blades. The generated flow encourages the fish 100 to enter the conduit 20.

The impellor 50 can generate a flow at a flow rate which stabilises the fish 100 during treatment as it cancels out some of the upstream force from the spray 36. The flow rate can also be used to prolong the fish’s presence at the treatment station 12 to allow a longer treatment time. The impellor 50 could also be connected to the fish detectors and responsive to the determined velocity of the fish 100. For instance, a fast swimming fish does not need further encouragement and increasing the downstream flow may be counterproductive. Indeed, the impellor 50 could be adapted to be reversible and, when a fast swimming fish is detected, operated to produce a flow in the upstream direction 104.

In other embodiments (not shown), the conduit 20 can have a closed wall which will entrap the downstream flow from the impellor 50. The conduit 20 can be shaped to modify the generated flow through the conduit 20. For instance, the conduit 20 could include a constriction which increases the flow rate (due to the Venturi effect) of the generated flow at the constriction. Alternatively, the conduit 20 could include an expanded portion at one section of the conduit for producing a decreased flow rate at the expanded portion.

The apparatus 10 could include one or more counting devices (not shown) for counting the number of parasites on the body of the fish 100. This could be done using an imaging device connected to a processor of a computer, and object recognition software for recognising and counting the parasites. A counting device can be used to monitor the health of the fish and the efficacy of the treatment of the apparatus 10. It is possible to provide counting devices at an entrance to the apparatus and at an exit so that the presence of parasites for a given fish before and after being treated by the apparatus 10 can be verified. It is also possible for the counting device to be used to selectively operate the delivery device depending on the state of the fish, for example the counting device could be coupled with the delivery device and treatment can be selectively applied only if a counted number of parasites is greater than a predetermined threshold.

The apparatus could also include one or more fish feed dispensers (not shown). A dispenser could be located just inside the inlet 22 for encouraging the fish 100 to enter the inlet 22. A dispenser could also be located at the treatment station 12 to encourage the fish 100 to pause at the treatment station 12.

The removed parasites can be captured, such as using filtration, and removed from the body of water. For example, a lower pressure pump unit (not shown) can be used to gently draw water and suck debris/lice into a pipe and away from the body of water. The debris and parasites could be filtered from the drawn water. Alternatively, the drawn water could be heated at a remote location away from the fish to destroy the parasites before being returned to the body of water.

Figures 3 and 4 show a second embodiment of an apparatus 10 for the removal of parasites from the body of a fish 100. Like features are given like reference numerals.

In this embodiment, the downstream and upstream directions are vertical directions.

The conduit 20 is vertically orientated and so has a horizontally orientated inlet 22 and outlet 24. The flow generating means generates a flow in a vertical direction. The conduit of this embodiment has a length (depth) of 0.75 to 1.25 m.

It is known that diadromous fish such as salmon leap from the water to climb upwards as they travel upstream. However, these fish also jump from time to time even when in still water where no climbing is required. This is thought to be for the purpose of regulating their swim bladder, although another theory is that they are attempting to use the impact when re-entering the water to remove fish lice. The second embodiment of the invention utilises this behaviour.

The apparatus 10 now includes a buoyant member in the form of an air filled ring 50 which is provided at the surface 101 of the water. The ring 50 has a diameter of around

3 m and extends to between 5 to 15 cm from the surface 101. It is therefore suitably dimensioned to allow a jumping fish to clear the wall of the ring 50 and into the apparatus 10. The ring 50 may have alternative dimensions, being sized according to the type of fish which it is desired to treat.

The conduit 20 is now in the form of a ramp which slopes downwards from the ring 50 to the outlet 24 which is provided at the centre of the ring 50 and at a depth below the ring 50 and the surface 101. The upper surface of the ramp defines the inlet 22. A fish 100 jumping into the apparatus 10 may land at an outer region away from the centre of the ring 50. The water at this region will be shallow due to the presence of the ramp.

This will encourage the fish to travel towards the centre. Therefore, the conduit 20 again biases the fish 100 towards the treatment station 12 which is located at the outlet 24.

Many types of fish will naturally proceed to swim downwards to the outlet 24 and will be treated as they pass the nozzles 34 of the delivery device. If a type of fish is reluctant to do this, further biasing means can be provided.

For instance, the apparatus 10 may be adapted to generate a whirlpool or vortex effect. This encourages the fish to move towards the centre of the conduit. There are a number of ways of producing this effect. One way is to provide an impellor 50 below the outlet 24 and, in this case, the impellor 50 is configured to draw water downwards. Water draining from the apparatus 10 will naturally swirl (due to the principle of the conservation of angular momentum). To promote this, the ramp can include spiral grooves which spiral towards the centre.

Figure 5 shows a third embodiment of the apparatus 10 and like features are given like reference numerals.

In this embodiment, a number of apparatus 10 are provided within the inner boundary defined by the ring 50. The apparatus 10 can be arranged in an array. One type of array is shown in Figure 5 but many alternative arrays are possible. For this embodiment, the slope of the ramp locally around each individual apparatus 10 can be significantly steeper than for the embodiment of Figures 3 and 4. In other words, the profile of the ramp is dimpled, with each dimple or pocket corresponding to the location of an apparatus 10. This reduces the likelihood of a fish 100 escaping the ring 50 and avoiding treatment.

The present invention provides a non-chemical and non-pharmaceutical method of treatment for removing parasites such as sea lice. After initial installation, it is inexpensive to operate as it does not rely on consumables (only electric power is required). Distress to the fish is believed to be minimal. Indeed, the treatment method is even similar to naturally occurring events that the fish might experience. It is readily adjustable and can be finely tuned to optimise the treatment. Also, the invention can be permanently installed and in use throughout the life cycle of the fish. Furthermore, the fish does not have to be removed from its natural environment. This in-situ treatment minimises any distress to the fish and also the cost of deployment of the treatment system because it can be left permanently in the cages.

Furthermore, the apparatus of the present invention can operate continuously such that parasite infestations are dealt with quickly. As soon as parasites are present they will be removed, so that further breeding of the parasites can be prevented. This is in contrast to existing solutions which must be selectively applied once a problem is detected.

Various modifications and improvements can be made to the above without departing from the scope of the invention.

Claims

1. An apparatus for the removal of parasites from the body of a fish, the apparatus comprising:

a treatment station;

2. The apparatus of Claim 1, wherein the medium comprises water.

3. The apparatus of Claim 1 or 2, wherein the medium includes one or more additives.

4. The apparatus of any preceding claim, wherein the delivery device is adapted to provide a uniform sheet of laminar medium flow.

5. The apparatus of any preceding claim, wherein the delivery device has a first nozzle and a second nozzle, and wherein a nozzle is provided at each lateral side of the treatment station for treating each side of the body of the fish.

6. The apparatus of any preceding claim, wherein the biasing means defines a direction which is downstream towards the treatment station and an opposite direction which is upstream away from the treatment station, and wherein the delivery device is adapted to deliver the flow of water in a direction which includes an upstream direction component.

7. The apparatus of Claim 6, wherein the delivery device is adapted to deliver the flow of water at an oblique angle relative to the upstream direction.

8. The apparatus of any preceding claim, wherein the delivery device is adapted to commence the flow prior to the fish arriving at the treatment station.

9.

The apparatus of any preceding claim, wherein the biasing means comprises a conduit having an inlet which the fish can enter and an outlet.

10. The apparatus of Claim 9, wherein the inlet has a diameter which is greater than the diameter of the outlet.

11. The apparatus of Claim 9 or 10, wherein the treatment station is provided at or near the outlet.

12. The apparatus of any of Claims 9 to 11, wherein the treatment station is located along a central axis defined by the conduit.

13. The apparatus of any of Claims 9 to 12, wherein at least a portion of the conduit is tapered or steps down in width for funnelling the fish towards the treatment station.

14. The apparatus of any preceding claim, wherein the conduit has a frame structure.

15. The apparatus of Claim 14, wherein the conduit comprises a cage or netting.

16. The apparatus of any preceding claim, wherein the biasing means includes means for generating a flow through the conduit.

17. The apparatus of Claim 16, wherein the flow generating means is adapted to generate a flow in the downstream direction.

18. The apparatus of Claim 16 or 17, wherein the flow generating means is adapted to generate a flow at a flow rate which is predetermined to stabilise the fish during treatment.

19. The apparatus of any of Claims 16 to 18, wherein the flow generating means is adapted to generate a flow at a flow rate which is predetermined to prolong the fish’s presence at the treatment station to allow a longer treatment time.

20. The apparatus of any of Claims 9 to 13, wherein the conduit has a closed wall and is shaped to modify the generated flow through the conduit.

21. The apparatus of Claim 20, wherein the conduit is shaped to increase the flow rate of the generated flow in at least one section of the conduit.

22. The apparatus of Claim 21, wherein the conduit includes a constriction at the section of the conduit for producing an increased flow rate at the constriction.

23. The apparatus of any of Claims 20 to 22, wherein the conduit is shaped to decrease the flow rate of the generated flow in at least one section of the conduit.

24. The apparatus of Claim 23, wherein the conduit includes an expanded portion at the section of the conduit for producing a decreased flow rate at the expanded portion.

25. The apparatus of any preceding claim, wherein the downstream and upstream directions are horizontal directions, and wherein the biasing means is horizontally orientated.

26. The apparatus of any of Claims 1 to 24, wherein the downstream and upstream directions are vertical directions, and wherein the biasing means is vertically orientated.

27. The apparatus of Claim 26, wherein the apparatus includes a buoyant member provided at the surface of the water.

28. The apparatus of Claim 27, wherein the conduit comprises a ramp which slopes downwards from the buoyant member to the outlet which is provided at a depth below the buoyant member.

29. The apparatus of any of Claims 26 to 28, wherein at least one of the flow generating means and the biasing means is adapted to generate a whirlpool or vortex effect.

30. The apparatus of Claim 27 or 28, wherein the outer boundary of the inlet substantially corresponds to an inner boundary defined by the buoyant member.

31. The apparatus of Claim 27 or 28, wherein a plurality of apparatus are provided within the inner boundary defined by the buoyant member.

32. The apparatus of Claim 31, wherein the plurality of apparatus are arranged in an array.

33. The apparatus of any preceding claim, including one or more fish detectors.

34. The apparatus of Claim 33, wherein a fish detector is provided at or near the treatment station, and wherein the fish detector is connected to the delivery device which is configured to perform treatment only if a fish is detected at the treatment station.

35. The apparatus of any preceding claim, including a counting device for counting the number of parasites on the body of the fish.

36. The apparatus of Claim 35, wherein the counting device comprises an imaging device connected to a processor of a computer.

37. The apparatus of Claim 35 or 36, wherein the counting device is connected to the delivery device which is configured to perform treatment only if the counted number of parasites is greater than a predetermined number.

38. The apparatus of any preceding claim including at least one fish feed dispenser.

39. A method of removing parasites from the body of a fish, the method comprising the steps of:

providing a treatment station;

40. The method of Claim 39, wherein the medium is delivered using a delivery device adapted to provide a uniform sheet of laminar medium flow.

41. The method of Claim 39 or 40, including delivering the medium simultaneously to each lateral side of the body of the fish.

42. The method of any of Claims 39 to 41, wherein the biasing means defines a direction which is downstream towards the treatment station and an opposite direction which is upstream away from the treatment station, and wherein the method includes delivering the flow of water at an oblique angle relative to the upstream direction.

43. The method of any of Claims 39 to 41, including commencing the flow of the medium prior to the fish arriving at the treatment station.

44. The method of any of Claims 39 to 43, wherein the biasing means comprises a conduit having an inlet which the fish can enter and an outlet.

45. The method of Claim 44, wherein the conduit has a frame structure.

46. The method of Claim 44 or 45, including generating a flow through the conduit.

47. The method of Claim 46, including generating the flow at a sufficient flow rate to entrain the fish in the flow.

48. The method of Claim 46 or 47, including generating the flow at a flow rate which stabilises the fish during treatment.

49. The method of any of Claims 46 to 48, including generating a flow at a flow rate which prolongs the fish’s presence at the treatment station to allow a longer treatment time.

50. The method of any of Claims 44 to 49, including shaping the conduit to modify the generated flow through the conduit.

5

51. The method of Claim 50, wherein the conduit is shaped to increase the flow rate of the generated flow in at least one section of the conduit.

52. The method of Claim 50 or 51, wherein the conduit is shaped to decrease the flow rate of the generated flow in at least one section of the conduit.

53. The method of any of Claims 39 to 52, wherein the downstream and upstream directions are horizontal directions and the method includes biasing the fish in a horizontal direction.

15

54. The method of any of Claims 39 to 52, wherein the downstream and upstream directions are vertical directions and the method includes biasing the fish in a vertical direction.

55. The method of Claim 54, wherein a buoyant member is provided at the surface of

20 the water.

56. The method of Claim 54 or 55, including generating a whirlpool or vortex effect.

57. The method of any of Claims 54 to 56, wherein an outer boundary of the inlet

25 substantially corresponds to an inner boundary defined by the buoyant member.

58. The method of any of Claims 54 to 56, including providing a plurality of apparatus within the inner boundary defined by the buoyant member.

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59. The method of Claim 58, wherein the plurality of apparatus are arranged in an array.

60. The method of any of Claims 39 to 59, including detecting the presence of a fish at or near the treatment station and performing treatment only if a fish is located at the treatment station.

61. The method of any of Claims 39 to 60, including determining the velocity of the fish as it approaches the treatment station and responsively adjusting at least one of the angle, pressure and timing of the flow delivered by the delivery device.

62. The method of any of Claims 39 to 61, including counting the number of parasites on the body of the fish and performing treatment only if the counted number of parasites is greater than a predetermined number.

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