NO20160800A1

NO20160800A1 - System for delousing fish

Info

Publication number: NO20160800A1
Application number: NO20160800A
Authority: NO
Inventors: Erik Westre
Original assignee: Optimarstette As
Priority date: 2016-05-11
Filing date: 2016-05-11
Publication date: 2017-11-13
Also published as: NO342036B1

Abstract

System for delousing fish, comprising a source of lice infected fish, a pump Device arranged for transporting fish from said source to a delousing module (200), a warm water source (300) arranged to provide lukewarm water to the delousing module (200). The delousing module (200) exhibits an inlet (201), an outlet (202), a fish flow path (203) there between including a bath (204a, 204b) with lukewarm water. Infected fish is guided through the bath (204a, 204b) for about half a minute. A rotary paddle Wheel (205a, 205b) with vanes (206) is arranged rotary in the bath. The space between adjacent vanes (206) defines compartments (215) arranged to accommodate and guide fish through the bath to remove louse.System for delousing fish, comprising a source of lice infected fish, a pump Device arranged for transporting fish from said source to a delousing module (200), a hot water source (300) arranged to provide lukewarm water to the delousing module (200) . The delousing module (200) exhibits an inlet (201), an outlet (202), a fish flow path (203) there between including a bath (204a, 204b) with lukewarm water. Infected fish is guided through the bath (204a, 204b) for about half a minute. A rotary paddle wheel (205a, 205b) with vanes (206) is arranged rotary in the bath. The space between adjacent vanes (206) defines compartments (215) arranged to accommodate and guide fish through the bath to remove louse.

Description

The present invention concerns a system and a method for delousing fish, as described in the preamble of claim 1 and 9.

Background

Salmon louse is a Crustacean that is living as a marine parasite on anadromous fish. The lice are living of the saliva, the head and the blood of the fish. Accordingly, the lice extract energy from the fish. Moreover, the lice cause wounds to the fish that may cause infections and problems with the salt equilibrium.

The presence of salmon lice is a severe problem in aquaculture, and is imposing a substantial negative impact with regard to cost and productivity. The fish welfare is of course also affected in a negative manner.

Accordingly, the fish farming industry has suggested numerous methods and device to delouse fish, e.g. preventive medication, chemical treatment to delay chitin synthesis in lice and hence stop ecdysis, and treatment with hydrogen peroxide.

Another approach is to subject lice-infected fish to freshwater for a period of time. Freshwater has the effect that the salt equilibrium in lice is challenged and disturbed, whereupon lice drop off the fish.

Yet another approach to remove lice from fish is to keep lice infected fish in a lukewarm water bath for about 30 seconds, whereupon lice is stressed by the temperature increase and drop off the fish.

An example of warm water treatment is described in NO 332298 Bl, where lice-infected fish is strained and fed to a treatment zone in the form of a U-shaped pipe containing lukewarm water. The fish is forced through the treatment zone by liquid flow.

While the latter approach by use of freshwater treatment has been shown to be at least partially successful, there is still a need for a more effective method for delousing anadromous fish.

Object

An object of the present invention is to improve the process of removing lice from anadromous fish.

The invention

A system in accordance with the present invention appears in the characterizing part of claim 1 and a method for delousing fish appears in the characterizing part of claim 9. Further advantageous features appear in the dependent claims.

Summary of invention

In general, a system in accordance with the present invention for delousing fish is arranged to receive lice-infected fish from a source. The system comprises a pump device arranged for transporting fish from said source to a delousing module, an optional fish counter, and a warm water source arranged to provide lukewarm water to the delousing module. The delousing module exhibits an inlet, an outlet, a fish flow path there between, including a bath supplied with lukewarm water where infected fish is to be kept for about half a minute. According to the invention, the treatment module exhibits at least one fish flow path comprising one or more com part men ts defined between partition walls or similar, wherein the compartments are arranged movable in the bath in the fish flow direction to move fish in the lukewarm water towards the outlet.

The compartments may be defined by space between adjacent vanes arranged rotary on a shaft, or by plate shaped devices attached to an endless chain arranged to rotate about shafts to guide the plate shaped devices, including the fish-containing compartments defined between the plate shaped devices, through the bath containing lukewarm water.

The partition walls or plate-shaped devices are preferably provided with apertures to allow water flow through the partition walls but prevent fish from exiting the compartment.

In a embodiment described in further detail below in connection with the attached drawings, the treatment module can exhibit:

-a first and second fish flow path including a first and second bath, respectively, and

-a fish guiding device located upstream of the first and second fish flow paths, arranged to direct fish flow intermittently to either the first or second fish flow path.

The first and second baths exhibits a first and second rotary paddle wheel, respectively, can exhibit numerous vanes, defining there between the compartments.

The fish guiding device mentioned above can be a trough håving a first and second side wall, a bottom between said side walls, an inlet and an outlet, and drive means to move the outlet between the first and second fish flow path.

A first washing station is advantageously arranged upstream of the delousing module to effect an initial removal of lice. Similarly, a second washing station can be arranged downstream of the delousing module.

Detailed description

Accordingly, in a system and a method in accordance with the present invention, fish infected with lice is transferred, e.g. from a sea pen, to a treatment or delousing module where the fish is subjected to lukewarm water in a bath for about half a minute. As described above, the fish is forced through the delousing module in baths with lukewarm water, in sealed compartments moving from an inlet of the bath to an outlet of the same, wherein the walls of the compartments preferably are perforated to allow water to flow there through but to prevent fish from escaping from the compartment.

Prior to treatment of fish in the treatment module, undersized fish and wrasse is preferably sorted out prior to being transferred to the treatment module, whereupon fish is optionally guided through a fish counter and further into the treatment module.

When the treatment with lukewarm water is completed, the fish is optionally flushed with water at the outlet of the treatment compartment to remove any remaining lice, whereupon the fish is being transferred back to the sea pen.

The treatment module is provided with water from a warm water source which comprises devices for supplying lukewarm water (for example at 30-34 °C), e.g. one or more buffer containers and heating devices. Spent water from the treatment zone is filtered to remove lice and other solids and impurities. Water in the buffer containers can be heated in numerous manners, for example by electrical heaters or oil heaters.

The system according to the invention also exhibits a control unit, arranged to control the detention time of fish in the treatment zone. The control unit receives information about water temperature in the treatment module, fish flow rate, warm water flow rate, and other process parameters. These parameters are used in calculations to secure correct treatment and stop the fish flow if the parameters cannot be within accepted deviation.

A thorough control of optimal fish retention period in lukewarm water during the delousing step should be within the reach of a person skilled in the art in view of common skill and support in the present disclosure.

Results from experiments have shown that more than 90 % of lice can be removed at an increased throughput compared to prior art systems. This is a substantial improvement compared to the prior art approaches. Another benefit is that the method does not involve use of any chemicals or medicaments.

The system according to the present invention can be implemented in numerous ways, e.g. as a modular assembly on a floating stage. However, it is also conceivable to assemble a system on a boat, or even as a land based plant in fish farms. However, a modular assembly on a floating stage is a preferred embodiment because a floating stage can be moved between sea pens to be treated. The floating stage can be towed, or be self-driven.

The detention period for fish in the treatment zone is of vital importance. If the detention period is too short, delousing will be ineffective. On the other hand, if the detention period is too long, the fish simply will die. The present invention provides a thorough control of fish flow rate, water temperature and detention period, thus producing an optimal delousing of fish with a high throughput.

Drawings

The invention is described in further details below by an example with reference to drawings illustrating one out of many embodiments of the present invention, where

Fig. 1 illustrates a strongly simplified process flow sheet of a delousing plant,

Fig. 2 illustrates a treatment module in accordance with the invention viewed in perspective from above,

Fig. 3 is a front view in perspective of a part of the treatment unit illustrated in Fig. 2,

Fig. 4 is a cross-section through one flow path in the treatment module along the direction of movement of fish, and Fig. 5 is a perspective view of the treatment module of Figures 2-4 above, by a front view in perspective from below.

Example

In the following, an embodiment of the present invention is described in the form of a modular system assembled on a floating stage.

Reference is now made to Fig. 1 which illustrates a strictly simplified process flow sheet of a delousing process. Fish is pumped in a continuous manner from a sea pen 100 by means of a rotary fish pump 101 and then quantified by a fish counter indicated by reference numeral 102. Then, the fish is flushed by water in a first washing station 103 supplied with water from a rinse water source 104 through line 105. Small fish and wrasse may optionally be removed (not illustrated) before the fish is transferred to a treatment module. Wash water from washing station 103 is removed in line 106 and guided to a filter unit 107 to strain the wash water and collect solid therefrom. Fish washed in the first washing station 103 is guided to a delousing or treatment module, indicated generally at reference numeral 200, where fish is subjected to a delousing step which includes submersion in lukewarm water for a short period of time. This step is described in further detail below in view of Figs. 2-5.

The lukewarm water is recycled between the delousing module 200 and a warm water source indicated generally by reference numeral 300. The warm water source 300 comprises one or more heated water buffers 301 supplied with recycled water from the treatment module 200 returned in line 302, together with a smell top-up of fresh water in line 303 including a control valve 304 to replace any water lost in the treatment module 200. Lukewarm water is withdrawn from container 301 in line 305 by a pump 306 into line 308, controlled by valve 307, and further into the delousing module 200. As mentioned above, spent warm water is after use recycled back to the warm water source 300 in line 302.

Fish subjected to the delousing process in treatment module 200 is optionally flushed in a second washing station 108, which operates in a similar manner to the first washing station 103 described above where spent water is guided to a filter unit 107. Deloused, and optionally flushed, fish is returned back to the sea pen 100, or to another sea pen (not illustrated) containing only deloused fish.

Now referring to Fig. 2, the delousing or treatment module 200 is described in further details. The treatment module 200 exhibits at its respective end a treatment module inlet 201 and a treatment module outlet 202. Downstream of the treatment module inlet 201, an inlet fish flow path is indicated at reference numeral 203. Downstream of the inlet fish flow path 203, the fish flow path 203a and a second fish flow path 203b. Moreover, the inlet fish flow path 203 is provided with a flow guiding means 220 arranged to direct fish moving the inlet fish flow path 203 either into the first fish flow path 203a or the second fish flow path 203b in a continuous oscillating manner. Here, the inlet fish flow path 203 is illustrated as a trough håving a bottom 223 and side walls 221, 222, arranged movable to direct fish flow either to the first fish flow path 203a or the second fish flow path 203b.

Each first 203a and second 203b fish flow path comprises a container 204a (only one container illustrated in Fig. 2) exhibiting a substantially semicircular bottom håving straight vertical side walls extending parallel to the direction of movement of fish passing there through, thus defining a first treatment bath described in further detail below. A first paddle wheel 205a is arranged rotary in the first container 204a, about an axis extending perpendicular to the direction of flow of fish in the first container 204a. Each paddle wheel exhibits numerous vanes indicated at 206. Each vane is preferably provided with apertures, e.g. slits as illustrated in Fig. 2, allowing water flow between adjacent vanes but preventing fish movement there between. A second paddle wheel 205b is arranged in a similar manner in the second fish flow path 203b, which together with a second container defines a second treatment bath.

A first warm water inlet 207a is arranged to supply lukewarm water from the warm water source 300 described above, to the first treatment bath 204a. A similar arrangement is provided for the second fish flow path 203b, which is not illustrated in Fig. 2. The first and second treatment bath 204a and 204b are each provided with an outlet 208a and 208b, respectively, through which spent lukewarm water is removed and recycled back to the warm water source 300.

At the treatment module outlet 202, the second optional washing station 108 described above in connection with Fig. 1 is arranged. The fish may be washed by water supply means (not illustrated), where water is drained through a strainer 209a and 209b and further to the outlets 208a and 208b, respectively. The fish is then guided down into a trough 210 flushed by water from water inlet 211 and guided out of the trough 210 through the treatment module outlet 202.

Now referring to Fig. 3, the treatment module 200 is shown in perspective in a front view, where components similar to those illustrated in Fig. 2 are provided with identical reference numeral. As is better apparent from Fig. 3, each vane 206 in the paddle wheels 205a and 205b are provided with numerous slits 212 in their surface to allow water flow between adjacent compartments defined by adjacent vanes 206. Moreover, the first and second paddle wheels 205a and 205b are mutually displaced about their respective axis of rotation, so that each vane of the first paddle wheel 205a is displaced about their axis of rotation, e.g. about one half distance between adjacent blades in a vane. The purpose of this displaced vane arrangement is described below. The vanes 206 are at least partially submerged in a bath in the respective first and second container 204a, 204b supplied with lukewarm water, and are arranged to rotate continuously and hence defining a treatment zone between adjacent submerged vanes 206 on the respective paddle wheel 205a, 205b. The treatment zone may also exhibit a device for supplying air or oxygen to the lukewarm water in the treatment zone (not illustrated).

In use, fish is supplied to the treatment module inlet 201 and guided into the first fish flow path 203a and further into the first container 204a containing lukewarm water during continuous rotation of the first paddle wheel 205a. The head blade viewed in the flow direction of the fish serves as a barrier to the fish being treated in the treatment zone, whereas the trailing vane blade serves as a guiding and transportation means forcing the fish through the treatment zone. The detention period of the fish is controlled by adjusting the speed of rotation of the paddle wheels, with a high degree of accuracy.

While fish is supplied to the first fish flow path 204a, fish supply to the second fish flow path 204b is closed. The first paddle wheel 205a, rotating at the same speed as the second paddle wheel 205b, continues rotation, and when a vane 206 of the first paddle wheel 205a is approaching the bottom part of the inlet fish flow path 203 (Fig. 2), the fish supply to the first fish flow path 205a is closed (by means of a not illustrated guiding means), and the fish supply instead directed to the second fish flow path 205b. Fig. 4 illustrates a cross-section along the second fish flow path 205b. A bottom surface of the second fish flow path 203b is at its downstream end arranged to the second container 204b exhibiting a semi-circular bottom defined by an arched bottom surface 214. Each vane 206 preferably provided with slits 212, exhibits an edge 213 arranged adjacent to the arched bottom surface 214 leaving a distance between surface container bottom 214 and vane edge 213 small enough to prevent fish from passing or being pinched there between. Adjacent vanes 206 defines a compartment 215 there between, wherein fish is being subjected to said lukewarm water while being transferred from the inlet 216b of the second warm water bath (container) 204b to it outlet 217b for about half a minute. Fig. 5 illustrates a perspective front view of the bottom part of the treatment module 200, where identical components illustrated in the other drawings are identified by identical reference numerals. Note that the water inlet 207a here is arranged in a different location than shown in Fig.

2, but this embodiment is only presented of illustrative purposes and does not affect the function of the treatment module. Moreover, the treatment module 200 is assembled on a frame 218 enabling a convenient modular form.

The illustrated embodiment with a two-part arrangement of the fish flow through the delousing module enables an intermittent flow of fish through the delousing module, without risk of clipping fish between a moving vane passing an edge of the inlet fish flow path 203 bottom.

Modifications

While the invention has been described by an embodiment håving two parallel treatment baths where fish is forced through the treatment baths by a paddle wheel partially submerged in the baths, the invention is not limited to this. The system according to the invention may be provided with only one treatment bath. In this case, the guiding device 220, 221, 222,223 can be omitted. It is also conceivable to provide three or more parallel treatment baths. Moreover, the means for moving fish through the treatment bath is not limited to the illustrated paddle wheel. A similar effect can be obtained by arranging numerous plates on a continuous loop of a chain or wire, thus defining the compartments between adjacent plates, wherein the plates are driven through the treatment bath by a drive means.

Claims

1. System for delousing fish, arranged to receive lice-infected fish from a source (100), wherein the system comprises a pump device (101) arranged for transporting fish from said source (100) to a delousing module (200), an optional fish counter (102), and a warm water source (300) arranged to provide lukewarm water to the delousing module (200), said delousing module (200) exhibiting an inlet (201), an outlet (202), a fish flow path (203) there between including a bath supplied with lukewarm water where infected fish is to be kept for about half a minute,characterized in thatthe treatment module exhibits at least one fish flow path (203) comprising one or more compartments (215) defined between partition walls (206), said compartments (215) being arranged movable in the bath (204a, 204b) in the fish flow direction to move fish in the lukewarm water towards the outlet (202).

2. The system according to claim 1,characterized in thatthe compartments (215) are defined by space between adjacent vanes (206) arranged rotary on a shaft (219).

3. The system according to claim 1 or 2,characterized in thatthe partition walls (206) are provided with apertures (212) to allow water flow through the partition walls (206) but prevent fish from exiting the compartment (215).

4. The system according to any one of the preceding claims,characterized in thatthe treatment module exhibits: -a first (203a) and second (203b) fish flow path including a first and second bath (204a, 204b), respectively, and -a guiding device (220, 221, 222, 223) located upstream of the first and second fish flow paths (203a, 203b), arranged to direct fish flow intermittently to either the first (203a) or second (203b) fish flow path.

5. The system according to claim 4,characterized in thatthe first and second baths (204a, 204b) exhibits a first and second rotary paddle wheel (205a, 205b), respectively, exhibiting numerous vanes (206), defining there between the compartments (215).

6. The system according to claim 4,characterized in thatthe guiding device is a trough håving a first and second side wall (221, 222), a bottom (223) between said side walls, an inlet (223) and an outlet (224), and drive means to move the outlet (224) between the first (203a) and second (203b) fish flow path.

7. The system according to any one of the preceding claims,characterized in thata first washing station (103) is arranged upstream of the delousing module (200).

8. The system according to any one of the preceding claims,characterized in thata second washing station (108) is arranged downstream of the delousing module (200).

9. A method for delousing fish, comprising the steps of: -transporting infected fish from a source (100), - optionally counting fish by a fish counter (102), - optionally flushing fish in a first washing station (104), - subjecting fish to lukewarm water in one or more baths (204a, 204b) for about half a minute,characterized inforcing fish through said one or more baths in a sealed compartment (215).