WO2018196936A1

WO2018196936A1 - Method and device for the control of lice in fish farming, in particular fish farming in territorial waters

Info

Publication number: WO2018196936A1
Application number: PCT/DK2018/050080
Authority: WO
Inventors: Annfinn Nortun; Jane T. NIELSEN
Original assignee: Annfinn Nortun; Nielsen Jane T
Priority date: 2017-04-27
Filing date: 2018-04-26
Publication date: 2018-11-01
Also published as: DK201700266A1

Abstract

In connection with fish farms on the territorial sea, when salmon and trout are breed, salmon lice are present, which, if they occur in larger amounts, may cause very large losses to the fish farm. Combating salmon lice must, according to regulatory requirements, most places take place through biological control, with parasite eating fish. Such parasite eaters, however, are very shy and seek shelter when digesting pickled lice, such shells are found naturally on the bottom seabed or the bottom of the territorial sea where the fish farm is located. In addition, many of these useful parasite eaters are lost when the salmon is pumped into transport vessels, resulting in financial loss for the fish farm. A device for improving the efficiency of the control of salmon lice with parasite eaters in fish farms (2), in particular fish farms (2) on the territorial sea comprising at least one mobile hide is provided in the form of a enclosure (6), the sides (16, 18) of which have openings (24, 26), which openings are blockable by releasable slide dampers (28, 106, 106) or dampers through which openings the parasite eaters can pass out and into the enclosure (6), where the enclosure comprises suspension facilities (22) cooperating with side boundaries (8) on the fish farm (2), or with float rings (4) cooperating with the side boundaries (8) of the fish farm, where the enclosure (6) by the suspension facilities (22) is maintained in a pre-selected depth below the water surface. The enclosure (6) may be made up of a plurality of composite tubular members (112) assembled in one or more blocks (114), the walls of which have an open structure (104) in a condition that prevents the passage of parasite eaters, except through the openings (24, 26), or be constituted of a material of closed structure and comprise a bottom (14), where the openings (24, 26) are located at a distance above the bottom (14) of the enclosure (6) wherein the bottom is provided with a layer of artificial seabed. A enclosure (6) for parasite eaters or a number of these are placed evenly over the surface of the fish farm and at the depth where the salmon / trout will typically be located. This results in an increase in efficiency of the parasite eaters,

Description

TITLE: METHOD AND DEVICE FOR THE CONTROL OF LICE IN FISH FARMING, IN PARTICULAR FISH FARMING IN TERRITORIAL WATERS.

The present invention relates to a device for control of lice in fish farming, in particular fish farming in territorial waters. The invention further relates to a method for enhancing the control of salmon lice in said fish farms using the device according to the invention.

In the following terms, names such as fish farms, seabed farming, would be understood as farms that are arranged at the territorial sea, i.e. at sea, in inlets or in larger lakes. When the term parasites are used hereinafter, this will include all kinds of parasites in said fish farm, including salmon lice. When used as the term parasite eaters in the following, this should be understood in the broadest possible sense, including lip fish.

Such fish farms consist of bag shaped netting boundaries located on the territorial sea or in outlets, in which larger populations of salmon or trout are bred to slaughter size. The net boundaries are typically conical netting, whose upper side edges are attached to a floating structure, and where the net hangs freely in the water above the sea- / outlet bottom. Approximately 90% of the salmon in the bag is located within a depth of 0-6 m.

In said fish farms occurs a large population of salmon and therefore it can't be avoided that such a large population of salmon attracts salmon lice.

The salmon lice adhere to the salmon's skin and eat the salmon's protective mucous membrane, skin and suck the salmon's blood. This opens up other infections, such as bacteria, fungi, and also affects the osmotic salinity of the salmon. In addition, the salmon lice contribute to reduced salmon growth. Salmon lice is the biggest cause of salmon fish loss during breeding, it is assumed that salmon lice bring losses in Norway totaling NOK 500 million annual (2016).

The salmon lice thrive best in salt water, where it grows all year and best when temperatures rise in the spring and thrive more slowly as a lower salt con- centration in the water, and where a salmon migrates from saline to freshwater, the lice are lost after about 14 days stay in freshwater. Where the salmon farms are located in outlets, with the influx of fresh water, spring layers are formed, with saline water having a greater density than freshwater, that is, typical in the upper meter of water depth, the occurrence of salmon lice is small, but then grows in line with salt content in the water. But since the salmon is between 0 and 6 m depth, the attack of salmon lice can't be avoided.

The veterinary authorities have established clear guidelines on how to fight the salmon lice and limit the amount of salmon lice that may be available per. salmon in fish farms. Combating salmon lice with chemicals is not permitted by reference to veterinary and environmental standards.

The control of salmon lice can advantageously take place by means of parasite eater fish e.g. such as lip fish which exists of eating salmon lice and the use of this biological control method has become a legal requirement in several countries that have fish farms at sea and in fjords. Thus lip fish are breed with intent for sale to salmon farms.

However, the problem is simply that the parasite eater is a shy bottom fish, and it thrives best if it has a pile of pebbles, gravel and seaweed where, after eat- ing, it seeks refuge between meals. Where salmon farms are located so that there is a large depth of water below the salmon farms, the parasite eater fish will have difficulty finding shelter, which means that the occurrence of this will not be sufficient in these waters to keep the stock of salmon lice at an acceptable level. There is also the problem that when the salmon is removed from the farm, this typically takes places by pumping the salmon into tankers transporting the salmon to the slaughterhouse or to other fish farms. When pumped over, it happens that the lip fish, which is actually part of the farm's "operating equipment", if it is to be said, is pumped with the salmon into the tanker, which causes the owner of the farm to lose part of the very useful lip fish, which is a prerequisite for the operation of the fish farm. This means that new lip fishes should be purchased to replace those who disappear with the salmon when the pool is re-used.

From WO 2016/186518 A1 (AQUA CIRCLE AS), a shed for lip fishes is known. The shed is located in the centre of a net bag basin, where the shed may be in the form of a tongs forest that grows for example a rope. The parasite eaters can then swim in and stay in the seaweed forest where it can digest the eaten salmon lice / parasites it has taken from the salmon in the net bag basin. This somewhat solves the problem of providing a shelter in which the parasite eaters can reside while digesting parasites, but it does not solve the problem of proximity to the level at which the bearers of the parasites are located nor do they contribute protect the lip fish from aspiration by over-pumping the salmon to transport vessels, as the tongue only provides sporadic protection of the lip fish.

Thus, it would be desirable if the lip fish could be stored in the level of the pool net in the fish farm where the salmon resides, as this would increase the ef- fectiveness of the removal of salmon lice by the lip fish and, further, to reduce the loss of lip fish, by emptying of the fish farm's salmon basins, as well as an appropriate transport possibility for the lip fish is also desirable.

By the invention it has been realized this is possible by at least one mobile shed, in the form of an enclosure whose sides have openings which, by lockable sliding damper or doors, are detachable, through which openings the parasite eaters can pass in and out, where the enclosure includes suspension facilities that cooperate with side boundaries on the fish farm, or with floating rings that interact with the farm's side boundaries where the enclosure by the suspension facilities is maintained at a pre-selected depth below the surface.

This ensures that the parasites after eating them well with salmon lice can find shelter in the immediate vicinity of the place where the salmon are located, and when they are hungry again, they can quickly find their way to the salmon in- fested with salmon lice.

In addition, the enclosure has the advantage that the sliding dampers or doors can be closed when the salmon are pumped into the tankers in the transport vessels transporting the salmon to the slaughterhouse or other fish farms.

Thus, using the mobile shed according to the invention, a solution is provided for the defects of the parasite skull disclosed in WO 2016/186518 A1 (AQUA CIRCLE AS), the sheds of the invention being located at precisely the level in the net bag basin where the salmon mainly are located which enables the parasite eaters to hide in the immediate vicinity of the salmon, and furthermore that the parasite eaters are protected against transfer to the transport ship, as they can be confined to the enclosure during the over pumping of the salmon. Due to the shyness of the lip fish, turmoil in and around the basin of the salmon will cause the lip fish to seek into the shed, that is, when the salmon is to be pumped, the lip fish can be easily scared into the shed, after which the open- ings in the enclosure are blocked, manually or by actuators, whereby the loss of lip fish by pumping the salmon to a tanker is considerably reduced, thereby saving money for the fish farm owner, as it is not so often will be necessary to purchase new lip fish.

That is to say, the parasite eaters that are in the hide are temporarily locked in, with the possibility of being let out again in the net basin when the pumping of salmon has been completed. As a result, the fish farm does not lose a large amount of parasite eaters, and these will be ready to continue to eat salmon lice when released from the shed. Using the hide according to the invention, in addition to the above benefits of more economic / practical nature, There is also achieved a considerable increase in the well-being of the fish found in the fish farm, since the salmon / trout therein will receive more frequent visits to the useful parasite eaters, as they do not have to swim so far to find shelter, and the parasites will live in the immediate vicinity of the place where their main source of food, salmon lice, is located. All in all, the invention lead to that all individuals living in fish farms using the sheds according to the invention may increase their welfare considerably. Additionally, the more effective control of the salmon lice which is enabled by the sheds according to the invention, that the use of antibiotics and other chemical control agents for the con- trol of salmon lice, which can be termed environmental pollutants which may damage other living organisms in the sea or on the territorial sea, can be minimized, perhaps even completely avoided, which must be considered a huge benefit to the aquatic environment. In a preferred embodiment of the hide according to the invention, the enclosure may be constituted by a number of composite tubular elements whose walls have an open structure of a nature that prevents passage of the parasite eaters except through the openings at the ends, said tubular elements being assembled in one or more blocks.

By the open structure of the walls of the composite tubular elements, the advantage is obtained that the parasite seats feel the necessary security by feeling flows in the surrounding water and therefore seeks into hide.

With the intent of keeping the parasite eaters in the hide, for example when pumping of trout / salmon located in the fish farm to transport vessels, the compo- site elements can be constituted by a single block enclosed by a frame similar enclosure whose two opposite sides at the openings have retractable lockable sliding dampers whereby the openings are blocked or open, and through which the parasite eaters can pass into and out of the enclosure, where the enclosure comprises suspension facilities which cooperate with side boundaries in the fish farm, or with floating rings interacting with the side boundaries of the farm where the enclosure by the suspension facilities are maintained at a pre-selected depth below the water surface.

In a further embodiment of the hide, the enclosure can be constituted by ma- terial with a closed structure with a bottom and where the apertures are located at a distance above the bottom of the enclosure and the bottom of the enclosure comprises a layer of artificial seabed.

It is preferred that a number of mobile hides are arranged distributed over a net bag pool, at a depth of 0,5 to 10 meters, typically 1 to 8 meters, and preferably 3 to 6 meters.

In this way it is achieved that the hide of the parasites can be placed at the depth where the occurrence of salmon lice is greatest, which increases the effi- ciency of the parasite eaters, as they do not have to stretch so long a distance between their shells and salmon carrying the salmon lice.

It is further preferred that the hides are arranged in the fish farms basins at a distance of approx. 3-15 meters, typically 4-13 meters, and preferably 5-10 me- ters, evenly distributed over the surface of the fish farm, and to the depth where the salmon is typically found in the net bag, thereby achieving that the lip fish are near the salmon all the time, and after eating salmon lice, they can swim into the hide, digest and rest before they swim out and eat more salmon lice.

With the intent of creating safety and concealment for the parasite eaters within the enclosure, the bottom of this can be provided with artificial seabed consisting of a layer of coarse sand, pebbles and artificial pliers. It is further preferred for combating bacteria, etc. that the seabed and artificial forceps are heat treated, and also heat treated in conjunction with periodic cleaning the containment.

This provides safe and good accommodation for the parasite eaters when they are to digest the pickled lice, and by the heat treatment, it is achieved that no bacterial bacteria are collected in the artificial seabed.

In order to counter the collection of faeces and feed residues on top of the enclosure according to the invention, it is preferred that the upper boundary of the enclosure is constituted by one or more sloping or inclined curved surfaces between the ridge and the foot.

In this way it is achieved that faeces from the salmon in the fish farm and feed residues are not easily accumulated on top of the enclosure, which contrib- utes to reducing disease risks.

In order to facilitate the operation of the sliding dampers at the enclosure openings in a first embodiment of the enclosure, these may be actuated or manu- ally operated by wire systems from the edge boundary of the float or the boundary of the pond, which respectively raise the sliding dampers, from which the sliding dampers respectively are lowered from a passive position in which the downward edge of the sliding dampers is suspended in spring-loaded locking pawls inserted into holes in the dampers, to an active position where the openings in the enclo- sure are blocked and the sliding dampers are located in a position where the downward edge of the dampers are in abutment with the lower end of the frame structure, and where the slide dampers are operated from the float ring or the side boundary of the pond by a wire releasable locking device comprising said spring- loaded locking pawls located on opposite sides of the framework structure.

In order to facilitate the operation of the sliding dampers/doors at the openings of the enclosure in another embodiment of the enclosure, these may be actuated or manually controlled by wire systems which respectively raise the sliding dampers / doors from their passive position where the downward edges of the slid- ing dampers/doors are resting against the first stop to an active position where the openings in the enclosure are blocked and the sliding damper/door is located in and a position where the upwardly facing edge of the sliding damper is located near second stops where the sliding damper is locked in a wire releasable locking device comprising two locks located on opposite sides of the enclosure, alternatively diametrically opposed.

This makes it possible to operate the sliding dampers / doors from the side walls of the fish farm without having to pull the entire hide up on the side boundary. That is to say, the parasite eaters in connection with pumping the salmon in fish farm to tankers can be scared into shelter in the enclosure and the openings of the enclosure can be blocked relatively quickly (less than a second) by pulling the wire, whereby the parasite eaters are trapped in the enclosure until the openings are re-opened, by deactivating the lock and lowering of the sliding damper / doors. This prevents the parasite eaters from being pumped into the tanker together with the salmon, thus remaining as an important part of the fish farm equipment that can be used for the release of new salmon in the fish farm. With the intent of facilitating the transport of the enclosure according to the invention, this may be provided with facilities or other support measures which makes it suitable for transport on a pallet truck or forklift truck. This makes it possible to use the hide for transport of the parasite eaters between their breeding places to the fish farm. In addition, the enclosure may also be used as a hatch for the parasite eaters so that they become safe and familiar with the surroundings. Also, within the enclosure, less shelter for parasite seedlings may be placed in the level below the gap openings, so the seedlings in the first lifetime will have a smaller and more appropriate hide. Because the enclosure is equipped with facilities that make it suitable for transport with pallet lifts or forklifts, it will also be easi- er to transport and handle the enclosure for cleaning and disinfection, etc.

It should be emphasized that although the containment is provided with said facilities, this is in no way bound to appear with any unique geometry.

In order to be able to carry out a visual check of the population density of parasites in the enclosure, the roof of the enclosure may include a transparent area.

This provides an opportunity for controlling the amount of parasite eaters in the enclosure/hide; however, this requires the enclosure to be located to allow access to the transparent area.

In another embodiment of the enclosure according to the invention wherein control of the amount of parasite eaters present in the containment is desired to be controlled without the occlusion being picked up in a position from which the population can be visually controlled, the roof may comprise a sensor detecting the population of parasite eaters in the enclosure. This is very advantageous as it allows for the control of the population of parasite eaters in the enclosure without altering the location of the enclosure in the fish farm, thus while the shelter is at rest. At a desired population of parasite eaters in the containment, the sliding damper can be displaced to the active position where the openings to the enclosure are blocked, thus blocking the parasite eaters inside the containment.

With the intent of enabling effective cleaning of the enclosure, including replacing or cleaning the artificial seabed in the enclosure, the roof can be detachable, alternatively hinged to the enclosure side.

This ensures complete access to the inside of the enclosure so that cleaning can easily be carried out.

In order to facilitate the handling of the enclosure when it is raised above the water level of the fish farm and at the same time being able to store living parasite eaters in the enclosure, its sides in a distance underneath the apertures, may comprise a bore, but above the bottom of the enclosure, consisting of holes with a diameter that does not allow passage of the parasite eaters.

This ensures that the amount of water contained in the submerged enclosure position in the fish farm which is located in the level above the holes will be will pass through the holes, but since the holes are located above the bottom of the enclosure sufficient water will remain in the enclosure so that the parasite eaters can breathe. This means the enclosure will not be heavy to move around, and therefore the transportation of these is significantly facilitated.

In order to ensure an easy handling of the enclosure between its placement in the fish farm and floating the rings or the side walls of the fish farm, the sliding damper wire system can consist of a first wire attached to the first end of the slide damper and another wire, attached to the other end of the slide damper, which wires at a distance above the upper boundary of the enclosure are assembled at a collection point from which a single third wire detachably connected to the collection point extends upward to a pickup system and which further comprises means for connecting an external lifting device.

The advantage of this is that the first, second and third wire is used partly for raising the damper and partly when the damper is closed to collect the entire containment with its contents of artificial seabed, water and parasite eaters, to a position from which the enclosure by use of other lifting means, such as an external crane on a ship, can be connected to the additional connection facility at the assembly point, whereby the first and second wire can be removed from the damper as well as the suspension facilities between the side boundary on the float ring or the fish farm and the enclosure can be released and the enclosure hoisted up, for example on a ship deck.

With the intent to keep the enclosure of the invention in as firm and steady position as possible, the suspension facilities can be constituted by at least three lines / wires extending between securing eyes on the outside of the enclosure and connecting points located on the side boundary of the floating and / or on the side boundary of the fish farm .

Using at least three attachment points, stability is achieved for its physical location in the fish farm. In order to be able to release the slide damper from the active position to the passive without having to raise the containment to the surface and within the manual range, the locking devices may be interconnected by a fourth wire whose center is connected to a fifth wire running through an opening in the enclosure upper boundary, said fifth wire being attached to a hold mechanism on the side boundary of the float ring or on the fish farm .

Hereby, the advantage is obtained that if only salmon is to be replaced in the pool of the fish farm, the parasite eaters may be scared into the enclosure and then the slide damper can be closed by pulling the third wire until the slide damper is locked in the locking device and the parasite eaters are locked up. After that, the salmon can be pumped to ship and new fish for feeding can be exposed to the pool in the fish farm, after which the fifth wire is released for release of the locking mechanism, and the third wire is released to lower the slide damper to the first lower stop. The advantage that the sliding damper rests against the first lower stop in the passive position is that the movements of the dampers follow the movements of the enclosure caused by the sea which may affect the limitation of the float ring or the side boundary og the fish farm. That result in, that parasite eaters are disturbed as little as possible by sea activity around the fish farm.

In order to ensure that there are no relative displacements between the upper boundary of the enclosure and its walls, the roof may be held in position by at least one vertically oriented tab comprising a through going opening for a lock bolt, which opening is positioned so, that the roof when the lock bolt is located in the through going opening is pressed against the walls of the enclosure.

This prevents relative displacements between the roof and walls in the enclosure that can scare the parasite eaters.

Due to the durability of the enclosure, the consideration of low weight, and the requirements of the food authorities, it is preferred that the enclosure, as well as the associated joints, wires and suspension system, are made of a plastic material approved by the food authorities and stainless steel approved for food production.

A method for enhancing the control of salmon lice in fish farms, in particular fish farms on the territorial sea, may be characterized by the following process steps;

-application of a population of parasite eaters and water in one or more hides ac- cording to any one of claims 1 -18,

-application of a number of hides evenly distributed over the surface of a basin in the fish farm and in different depths within the range of 0.5 to 10 meters, typically 1 to 8 meters, and preferably 3 to 6 meters,

-displacement of the sliding dampers to the passive position, whereby the open- ings in the enclosure are free to pass for parasite eaters.

This ensures that the parasite eater has a hide to hide that is located in the depth and position in which the salmons / trout are located while digesting the salmon lice they have eaten. This means that the parasite eater fish does not have to have to recede longer stretches between their hide and salmon in the fish farm after they have digested the ate salmon lice. The invention will now be explained in more detail with reference to the accompanying drawings, in which:

Fig. 1 is a perspective view of a basin in a sea fish farm comprising float rings in which are suspended hides for parasite eaters in the form of enclosures according to the invention,

Fig. 2 is a detail perspective view of a float ring in which is suspended a first embodiment of a hide for parasite eaters in the form of an enclosure according to the invention,

Fig. 3 is a perspective view of a first embodiment of a hide for parasite eaters according to the invention,

Fig. 4 is a detail view of the wire assembly point used for displacement of the damper between a passive and an active position, as well as for the lifting of the hide shown in Fig. 2 and Fig. 3

Fig. 5 is a perspective view of the first embodiment of a shed for parasite eaters according to the invention in which one side of the roof is made transparent and the sliding damper is in passive position,

Fig. 6 is a perspective view of the first embodiment of a hide for parasite eaters according to the invention in which one side of the roof is made transparent and the sliding damper is in active position,

Fig. 7 is a detail perspective view of an end of the first embodiment of the hide according to the invention, showing the roof fastener mechanism, and the slide damper locking mechanism, Fig. 8 is a detail view of another embodiment of a hide for parasite eaters according to the invention, wherein the sides of the enclosure have an open structure and wherein the sliding dampers at the apertures of the hide are lowered, Fig. 9 is a detail view of the one shown in Fig. 8 shows the embodiment of the hide for the parasite eaters according to the invention, wherein the sliding dampers at the apertures of the hide are raised,

Fig. 10 is a detail view of the one shown in Fig. 8 and Fig. 9 embodiment of the hide for parasite eaters according to the invention where the open structure of the enclosure is shown during insertion or removal, Fig. 1 1 is a detail perspective view of the open structure of the containment shown in Fig. 8, Fig. 9 and Fig. 10,

Fig. 12 is a perspective view of a floating ring in which is suspended a third embodiment of a hide for parasite eaters in the form of an open structure enclosure as shown in Fig. 8, Fig. 9, Fig. 10 and Fig. 1 1 , according to the invention,

Fig. 13 is a detail perspective view of the one in Fig. 12 shown third embodiment of a shed for parasite eaters according to the invention, and Fig. 14 is a detail perspective view of the one in Fig. 12 shown embodiment of a shed for parasite eaters according to the invention provided with fenders.

Position Numbers:

2 fish farm

4 float rings

6 mobile hide

8 side boundaries on fish farm 2

10 first anchoring line

12 other anchoring lines between flow rings 4

14 bottom of the mobile hide 6

15 leg below 14

16 parallel long sides of mobile hide 6

18 gable end of mobile hide 6

20 upper boundary of mobile hide 6

22 suspension liner / wires for mobile hide 6

24 slotted openings in 16 25 fastening eyes for 22

26, 26^' opening in gable 18

28 surrounding damper

30 lower edge of 28

32 stop knobs on the outside of the hide 6

34 protruding plate-shaped part of the sliding damper 28

36 first wire attached to 34

38 other wire attached to 34

40 collection point for 36, 38

42 third wire connected to 44

44 block with tracked wire wheels

46 tracked wire wheels

48 U-shaped bar for 44.46

50 stand

52 hand operated games on stand 50

54 upper stop on hide 6

56 upper edge of damper

58 guide tubes anchored to the gables 18

60 spacer brackets for 58 on the gables 18

61 take out in the enclosure saddle roof 20

62 transparent plate piece over 61

64 sloping portion 66 of 34 facing away from the gable

68 take out in the plate-shaped portion 34

70 horizontally oriented locking plate 70, located on the inner end sides 72 protruding plate pieces

73 take out cooperating with 72 in the gables 18

74 draw ring on 72

76 fourth wire connected to 74

78 fifth wire 78 connected to 76

80 hole in the saddle roof

82 ridge of 20

84 second track-cut wire wheel

86 other stand anchored to the float ring 4

88 bores in the longitudinal sides 16

90 blunt upside protruding tap on 60

94 through going take outs in 90

96 locking device 96 cooperating with the pin 90 100 ring or shackle for joining of 36 and 38

102 second ring or shackle connected to the third wire 42

104 open structure

106 slide damper

107 bottom edge of slide damper 106

1 10 frame-shaped structure

1 12 pipe pieces

1 14 box-shaped block of 1 12

1 16 spring-loaded locking pins

1 18 rectangular holes

120 upper hole in 106 for the receive of 1 16

122 lower hole 106 for the receive of 1 16

124 upper edge of block 1 14

126 upper end of 1 10

128 lower end of 1 10

130 first surrounding fender at 126

132 corners of 1 10 at 126

134 second surrounding fender at 128

136 corners of 1 10 at 128

Fig. 1 is a perspective view of a basin 2 in a sea fish farm comprising float rings 4 in which are suspended hiding 6 for parasite eaters in the form of enclosures 6 according to the invention. The basin 2 is carried by a side boundary 8 to which the rings 4 at the first anchoring lines 10 are attached. In addition, there are other positioning lines 12 between the rings 4, whereby the mutual distance between the floats 4 is maintained. The location of the float rings 4 thus determines the location of the shells 6 so that they are evenly distributed over the basin surface. In the following, the terms hide, shed parasite eater hide/shed shall be understood as the enclosure 6, and these terms will be used randomly.

Fig. 2 is a detail perspective view of a float ring 4 in which is suspended a shed 6 for parasite ears in the form of enclosures according to the invention. The shed 6 is formed in the embodiment shown as a box-shaped enclosure 6 having a rectangular base shape comprising a bottom 14 (see Figure 5), two parallel longitudinal sides 16, two gables 18 and an upper boundary 20 which in the shown embodiment is constituted by a saddle roof 20 and in the following, there will be referred to either a saddle roof 20 or the upper boundary of the enclosure 20. The reason that a saddle roof 20 is not uniquely used as the upper boundary of the enclosure 6 is that the enclosure may accept other basic shapes than the rectan- gular shown in the embodiment. The cover 6 is suspended in four suspension lines / wires 22 which, as more clearly shown in Fig. 3 and Fig. 5 is detachably attached to fastening eyelets 25 in the gables 18 of the box-shaped enclosure 6.

As it appears from Fig. 2, but more clearly from Fig. 3, Fig. 5 and Fig. 6, the enclosure 6 comprises a plurality of slit-shaped apertures at a level above the bottom 14 of the enclosure 6. The slot-shaped apertures comprise a slot-shaped aperture 24 in each longitudinal side 16, and a slit-shaped, weak V-shaped aperture 26 in each of the gables 18. As can be seen from Fig. 2, Fig. 3, Fig. 5 and Fig. 6, the box-shaped enclosure 6 has a surrounding sliding damper 28, which can take an active position, in which it covers and blocks the gap-shaped openings 24, 26 in the longitudinal sides 16 and the gables 18 and a passive position (see Figure 5) , where the lower edge 30 of the slide damper 28 rests against protruding stop knob 32 on the out- side of the shed 6 (see Figure 5), and wherein said slot-shaped openings are free from passage of parasite eaters out and into the shed 6.

As is further apparent from the mentioned figures, but most clearly from Fig. 5 and Fig. 6, the damper 28 has a protruding plate-shaped portion 34 at the center of each of the gables 18, which is assembled through a first wire 36 fastened to the slide damper and a second wire 38 secured to the slide damper are in a collection point 40 which comprises at least one assembly ring / shackle or the like. It should be noted that the first and second wires 36, 38 may be releasable attached to the slide-shaped part 34 of the slide damper.

The assembly point 40 is releasable connected to a third wire 42 leading up and being connected to a block 44 with a track cut wire wheel 46 on the center of a mainly inverted U-shaped beam 48 which is anchored to the float ring 4, from which the third wire 42 is connected to a first stand 50 with a hand-operated game 52 intended for lifting and lowering the shelf between the position shown in Fig. 2, hanging in the suspension lines / wires 22, and a raised position where the collect- ing point 40 is located between the water surface of the fish farm and the track cut wire wheel 46.

As most clearly shown in Fig. 3, 4 and 6, the enclosure includes upper stop 54 designed for opposing the upper edge 56 of the slide damper 28. These upper stops 54, in the illustrated embodiment of the enclosure 6, are identical to the bodies of the fastening eyes 25. The upper stops 54 serves as counter holds for the slide damper 28 when it is raised to its active position and the hide 6 is desired to be raised upward against the water level in the fish farm by the hand-operated game 52 where the enclosure 6 thus is carried in the contact points between the top edge 56 of the slide damper and the upper stop 54 and in the first, second and third wire 36, 38, 42.

The first, second and third wire 36,38,42 thus serves two purposes, the first to raise and lower the slider between the passive and the active position, and partly to raise and lower the shelf between its submerged position in the fish farm, hanging in the suspension lines / wires 22 and to a position where the joint point 40 is located between the water surface and the track cut wire wheel 46 in the block 44 on the inverted U-shaped beam 48 which is anchored to the float ring 4.

Fig. 4 is a detail view of the assembly point 40 where the first wire 36 and the second wire 38 are assembled in a first ring or shackle 100 which is connected to another ring or shackle 102 connected to the third wire 42. It is assumed that the first ring or shackle 100 is large enough to also connect an additional ring or cable (not shown) connected to an external crane, for example on a service ship, so that the enclosure / hide 6 can be fully released from float ring and carried in the first ring 100 by handling the hide/enclosure 6 between the float ring 4 and a ship deck.

As can be seen from Fig. 5 and Fig. 6, but most clearly from Fig. 7, the first and second wires 36, 38 are guided in guide tubes 58, anchored to the gables 18 with spacers 60 for the purpose of protecting the saddle roof against damage when the enclosure 6 is lifted up and down from the float ring 4.

As can be seen from Fig. 2,3,5,6 and 7, the saddle roof 20 includes a takeout 61 covered with a transparent sheet piece 62 which serves to make visual control of the interior of the enclosure 6, including controlling the artificial seabed, and the presence of parasite eaters in the shed. The sloping roof surfaces on the saddle roof 20 serves to counter the accumulation of faeces from the salmon or trout in dams, and against the accumulation of feed residues. As can be seen from Fig. 5 and 6, the protruding plate-shaped portion 34 of the slide damper 28 comprises, in the upper end 64 adjacent to the gable 18, a sloping portion 66 which is finished with a take out 68 in the plate-shaped portion 34 cooperating with a horizontal oriented locking plate 70 which is supported on the inner gable sides'! 8. The locking plate 70 is constituted by a recessed end por- tion of a protruding plate piece 72 projecting through a cooperating take out 73 in the gables 18. The protruding plate piece 72 is attached to the gables 18 together with spacers 60. As it further can be seen, the protruding plate piece 72 is provided with a drag ring 74 connected to a fourth wire 76 connecting the protruding plate pieces 72 at each of the gables 18. As further shown in FIG. 5,6 and 7, the fourth wire 76 at the center is connected to a fifth wire 78 extending upwardly through a hole 80 in the ridge 82 of the saddle roof and further up to the block 44 to a second track cut wire wheel 84 and further thence to another post 86 which is anchored to float the ring 4, to which the end of the fifth wire 78 is releasable attached.

By this construction, the following are obtained. The sliding damper 28 can be lifted from its passive position by the hand-operated spindle 52, resting on the lower stop 32 to the active position where the sliding damper obstructs the openings 24, 26 on the sides of the enclosure. During the retrieval of the slide damper 28, the sloping portion 66 will come into engagement with the locking plate 70 whose protruding portion 72 will yield until the outlet 68 is reached, after which the locking plate 70 displaces itself by the spring force of the plate piece 72 into the socket 38, cf. Fig. . 6, after which the slide damper 28 is locked in the active position, the openings 24, 26 of the hide 6 are blocked by the slide damper. The slider damper is triggered by pulling the fifth wire 78 located at the second post 86 while the hand-operated spindle 52 is triggered. Hereby, the protruding portion 72 and hence the locking plate 70 are pulled out of the take out 38 and the sliding damper 28 is now released and can be lowered to its passive position resting on the lower stop 32. The advantage of the locking arrangement 68, 70, 72 for the slide damper 28 is further that the openings of the hide can be kept closed when transporting the hide containing parasite eating fish, artificial seabed and water. As further shown in Fig. 3, 5 and 6, each of the longitudinal sides 16 comprises a bore 88 which serves to drain the shed of water to the level of the bores above the bottom of the enclosure 6. This facilitates the handling of the shelf 6, the weight of which is considerably reduced by removal of the water otherwise would be located above the cavities 88.

As can be seen most clearly from Fig. 7, the saddle roof 20 is anchored to the gables 18 of the enclosure 6, as the spacer 60, closest to the ridge 82 of saddle roof comprises a blunt upwardly protruding pin 90 cooperating with the take outs 92 at each end of the ridge 82 of saddle roof, said pins 90 have a length that they protrude slightly above the ridge 82 of the saddle roof. The pins 90 comprise a through going take out 94 for receiving a tab-engaging locking device 96 which locks the roof in the properly mounted position. The take out 94 is positioned such that the saddle roof 20 in its correctly mounted position is pressed against the gables 18 and the longitudinal sides 16 and held in this position by the locking devic- es 96. Thus, the saddle roof 20 is tensioned in its correctly mounted position on the enclosure 6, which results in that the sea around the shelf 6 does not cause thunderous sounds that can scare the parasite eaters away from the hide.

As can be seen from Fig. 2, 3, 5 and 6, the hide in the illustrated embodiment comprises legs 15 extending downwardly from the bottom 14 of the enclosure.

These legs 15 serve to facilitate the handling of the enclosure / hide 6 when it is to be transported on shore, for example with a pallet lift or forklift truck. Obviously, the inventor has recognized that other suitable embodiments of attributes descending from the bottom of the containment 14 may be selected for convenient transportation with the aforementioned means of transportation than those shown herein.

Fig. 8 is a detail view of another embodiment of a parasite eater shed 6 according to the invention, wherein the sides 16 of the enclosure 6 has an open structure 104, and where the enclosure ends each have a slide damper 106, 106 '. The sliding dampers at the openings 26 located in the end ends 18 to the shed are lowered to the active position. Fig. 9 is a detail view of the hide 6 for parasite eaters shown in Fig. 8 according to the invention, wherein the slide dampers 106, 106 ' at the apertures 26, 26' to the shed 6 are raised to the passive position.

In the following, reference is made to Fig. 8 and Fig. 9. As most clearly seen in Fig. 9, the enclosure 6 is constituted by a frame-like structure 1 10 in which is inserted a plurality of pipe pieces 1 12 assembled in a box-shaped block 1 14. The wall of the pipe pieces 1 12 has an open structure 104 however it does not allow passage of parasite eaters. The box-shaped block 1 14 of assembled pipe pieces 1 12 allows only the parasite eaters to pass in and out of the hide 6 through the openings 26, 26 'at the ends of the block 1 14, which ends, as seen in FIG. 8, are block able by the slide dampers 106, 106 '. The sliding dampers 106, 106 are lockable by spring-loaded locking pawls

1 16 positioned on the upper end 1 18 of the frame-like structure 1 10, and the locking pawls 1 16 are constantly pressed against the forward position by spring action. The sliding dampers 106, 106 ' has, as most clearly shown in Figs. 9, two with the locking panels cooperating holes 120, 122 for receiving the forward positioned locking pawls 1 16.

The top hole 120 is utilized in the operating situation of the shelf 6, where the parasite eaters can pass freely in and out through the openings 26, 26 'in the ends of the pipe pieces 1 12 in the block 1 14 but where the lower side 107 of the slide dampers 106, 106' protrudes a little below the upper edge 124 of the block 1 14 of pipe pieces 1 12 thereby retaining the block 1 14 in the frame-like structure 1 10. This embodiment of the hide 6 comprises only facilities for closing the hide upon release of the slide dampers 106, 106 ' by pulling in the wire 78 connected to a wire 76 connecting the two spring-loaded locking pins 1 16. Pulling in the wire 78 will cause the locking pins to be pulled out of the holes. The wire 78 is led to a second post 86 anchored on the float ring 4. After the slide dampers 106, 106' are lowered and the openings 26 in the end ends 108 are blocked, these can't be raised again, thus requiring a retrieval of the cover 6, and a manually displaced slide sliders 106, 106 'to the open position where the openings in the gables 18 are free. This embodiment is therefore most suitable for farms located in quiet flow conditions, as the possibility of unauthorized release of the slide dampers 106, 106' may occur in turbulent weather. As it appears from Fig. 8 to Fig. 10, the frame-like structure 1 10 further includes an upper boundary 20 over that part of the structure 1 10 which houses the block 1 14 of pipe pieces 1 12. The upper boundary 20 is in the illustrated embodiment formed as a saddle roof, but may assume other configurations, e.g. the up- per boundary can be curved. The boundary serves to prevent dirt, faeces and feed residues from penetrating the hide 6.

The lower hole 122 is used to lock the slide dampers 106, 106 ' in a position where the bottom side 107 of the slide dampers 106, 106' is positioned a little above the upper edge 124 of the block 1 14 of pipe pieces 1 12, whereby the block 1 14 of pipe pieces 1 12 can be removed from the frame-like structure 1 10, as shown in Fig. 10. In this way it becomes possible to remove the block 1 14 of contiguous pipe pieces 1 12 from the frame-like structure 1 10 and clean it and subsequently re-insert the block 1 14 into the frame-like structure.

Fig. 1 1 is a perspective view of the box-shaped block 1 14 of open-ended composite pipe pieces 1 12, which in the illustrated embodiment are shown as rectangular holes 1 18 of tubular pieces. It should be stated here and therein that the inventor has realized that in this embodiment showed open structure may take numerous designs in which the open structure has different geometries than that shown in the embodiment.

As further shown in Fig. 1 1 , the pipe pieces 1 12 of the block of the same 1 14 may have different diameters, as exemplified by the shown pipe piece 126. By varying the diameter of the pipe pieces 1 12 in the block 1 14, a current parasite eater may choose the optimum size of hide that is preferred for the current size of parasite eater.

Fig. 12 is a perspective view of a float ring 4 in which a third embodiment of mobile cover 6 for parasite livers in the form of a frame-shaped structure 1 10 with an enclosure in the form of a block 1 14 consisting of open-ended composite tube

1 12 as shown in FIG. 8, Fig. 9, Fig. 10 and Fig. 1 1 , according to the invention is suspended in lines / wires 22. Fig. 13 is a detail perspective of the figure in Fig. 12 shown shed.

This embodiment of the shed 6 comprises means for raising and lowering the sliding dampers 106, 106 ' in the lowered position of the hide 6, as this embodiment, in addition to the facilities for closing the hide, by release of the sliding dampers 106, 106' by the wire 78, also comprises facilities for raising and lowering the sliders 106, 106 ' from a position on the float ring 4. The principles of rising and lowering of the sliders 106, 106' are approximately identical to those previously described with respect to the first embodiment of the shed 6. Sliding dampers 106, 106' are each connected to a wire 36, 38 leading to a game comprising a block 44 with trace cut wire wheels 46 arranged on a U-shaped beam 48 which passes across the float 4. The game is operated by a hand-operated game 52 on the post 50 on the float 4. The game 52 can also be used to lift the hide up to the water surface in the fish farm, after which external crane units are used for further handling of the hide 6. The release wire 78 can be used for hauling of the hide be- tween the submerged position in the fish farm, to the water surface, in cases where the dampers 106, 106 ' are desired to be held in the closed position so that the parasite eaters are trapped within the hide 6 .

Fig. 13 is a detail perspective view of the embodiment shown in Fig. 12 of a third embodiment of a hide for parasite eaters according to the invention.

Fig. 14 is a detail perspective view of the third embodiment of the mobile hide 6 of for parasite eaters according to the invention wherein the frame-shaped structure 1 10 of the upper end 126 is provided with a first circumferential fender 130 for covering the corners 132 of the upper end 126 of the frame structure 1 10 and further second circumferential fender 134 in the lower end 128 of the frame structure 1 10 to cover the corners 136 of the lower end 128 of the frame structure 1 10. The fenders serve in part to protect the fish which is located in the fish farm and the other circumferential fender 134 in the lower end 128 of the frame structure 1 10 may be filled with sand for the purpose of acting as ballast for the hide 6. The reason is that the hide may be formed of materials whose density may be less than density of the water in which the hide is emerged, why some extra weight may be required to keep the hide 6 in preferred depth in the fish farm pool 2. The embodiment shown in Fig. 14 of the cover 6 for parasite eaters is attached to the float ring 4 in the same manner as previously described.

It is to be noted that all wires, be it suspension lines 22, the first and second wires 36, 38, the third wire 42, the fourth wire 76 and the fifth wire 78, all of which are arranged to be removable so that shear -let / containment 6 can be released completely from floating point 4. In conclusion, it should be noted that the inventor has acknowledged that enclosure 6 can assume countless shapes than those shown in the drawing and disclosed above, for example, the shed could be formed with a circular basic shape, but it does not change the inventive aspect of facilitating the control of salmon lice in marine fish farms by establishing hides in the form of lockable enclosures as described above, thus providing a hide for parasite eaters while these digest salmon lice and, in addition, that the parasite eaters are not lost by over pumping / emptying of the fish farm's net inclusions for salmon, but while this is performed, the parasite eaters can be kept in closed shelves so that they are not pumped to the tanker's and thus removed from the fish farm.

Furthermore, the advantage is that since there is no need to be introduced so many new parasite eaters from the outside, the risk of infection by the introduction of new parasites is avoided.

Claims

A device for improving the efficiency of ihe control of salmon lice with parasite eaters in fish farms, in particular fish farms (2) on the territorial sea, character- ized in that it comprises at least one mobile hide (6) in the form of a enclosure (8) the sides (16, 18) of which have openings (24, 26), which openings are block able by reieasable slide dampers (28, 106, 106 ') or dampers through which openings the parasite eaters can pass out and into the enclosure (6), where the enclosure comprises suspension facilities (8) cooperating with side boundaries (8) on the fish farm (2), or with float rings (4) co-operating with the side boundaries (8) of the fish farm, where the enclosure (6) by the suspension facilities (22) is maintained in a pre selected depth below the water surface.

2. Device according to claim 1 , characterized in that the housing is made up of a plurality of composite tubular members (1 12) assembled in one or more blocks (1 14), the walls of which have an open structure (104) in a condition that prevents the passage of parasite eaters, except through the openings (24, 26).

3. Device according to claim 2, characterized in that the composite elements are constituted by an integral block enclosed by a frame-shaped structure (1 10) whose two opposite sides (16, 18) have lockable slide dampers (106, 106 ') or doors is located by which the openings (24, 26) are block able, and through which openings the parasite eaters can pass into and out of the enclosure (6), the enclosure comprising suspension facilities (22, 25) cooperating with side boundaries (8) on the fish farm (2) or float rings (4) that co-operate with the side boundaries of the fish farm (8), where the enclosure (6) by the suspension facilities (22) is maintained at a preselected depth below the water surface.

4. Device according to claim 3, characterized in that the frame-shaped struc- ture (1 10) is provided with a first circumferential fender (130) at the upper end

(126) for covering the corners (132) of the upper end (126) of the frame-shaped structure (1 10) and further a second circumferential fender (134) in the lower end (128) of the frame-shaped structure (1 10) to cover the lower ends (128) of the frame structure 1 10.

5. Device according to claim 4, characterized in that the first circumferential fender (130) and / or the second circumferential fender 134 is arranged as a ballast for the device. 6. Device according to claim 1 , characterized in that the enclosure (6) is constituted of material closed structure and comprises a bottom, and wherein the openings (24,26) are located at a distance above the bottom (14) of the enclosure and the bottom (14) of the enclosure includes a layer of artificial seabed. 7. Device according to any one of claims 1 to 6, characterized in that a number of mobile hides (6) are evenly distributed over the surface bounded by a net bag basin (3), at a depth of 0,5 to 10 meters, typically 1 - 8 meters, and preferably 3 to 6 meters. 8. Device according to any one of claims 1 to 7, characterized in that the hides (6) are evenly distributed in the basins of the fish farm (3) at a distance of approximately 3-15 meters, typically 4-13 meters, and preferably 5-10 meters.

9. Device according to any of claims 6-8, characterized in that the bottom (14) of the enclosure is provided with artificial seabed consisting of a layer of coarse sand, pebbles and artificial pliers.

10. Device according to any one of claims 6-9, characterized in that the seabed and the artificial sea weed are heat treated.

1 1 . Device according to any one of claims 1 to 10, characterized in that the upper boundary (20) of the enclosure is constituted by one or more inclined or sloping curved surfaces between the ridge (82) and the foot (83). 12. Device according to any one of claims 1 -1 1 , characterized in that the slide dampers / gates (28, 106, 106 ') are actuator driven.

13. Device according to any one of claims 1 to 4, characterized in that the sliding dampers (106, 106 ') at the openings (26) of the enclosure are manually operated by wire systems (42, 76, 78) from the edge boundary of the float ring (4) or the side boundary of the fish farm (8), from which the dampers (106, 106 ') are respectively lowered from a passive position where the downwardly facing edge (107) of the dampers / gates (106, 106') is suspended in spring-loaded locking pins (1 16) inserted into holes (120) in the dampers / gates (106, 106 ') into an active position where the openings (26) of the housing (6) are blocked and the slide dampers (106, 106') are located in a position wherein the downwardly facing edge 5 (107) of the sliding dampers / gates (106, 106 ') is in abutment with the lower end (128) of the frame-shaped structure (1 10), and wherein the dampers / gates (106, 106') are operated from the side boundary of the float ring or the fish farm by a wire releasable locking device (86, 78, 76, 42, 52, 44, 42) comprising said spring actuated locking posts (1 16) located on opposite sides (18) of the frame structure i o (1 10).

14. Device according to any one of claims 6-12, characterized in that the slide dampers (28) at the openings (24, 26) of the enclosure are manually operated by wire systems (36, 38, 40, 42, 76, 78) from side boundaries of the float ring

15 (4) or the side boundary (8) of the fish farm from which the sliding dampers/gates (28) are respectively raised from a passive position where the downward facing edge (30) of the dampers/gates (28) rests against the first stops (32) to an active position in which the openings (24,26) of the enclosure (6) are blocked and the slide damper (28) is located in a position where the upwardly facing edge (56) of

20 the slide damper (28) is located near the second stops (54) and where the slide damper (28) is locked by a wire releasable locking device (70, 72) operated from the side boundary of the float ring or the fish farm, said locking device comprising two locks located on opposite sides (18) of the enclosure (6), alternatively diametrically opposite.

25

15. Device according to any one of claims 1 -14, characterized in that the enclosure (6) is provided with facilities (15) or other support measures (15) which makes it suitable for transport on a pallet lift or a forklift.

30 16. Device according to any one of claims 1 -15, characterized in that the upper boundary (20) of the enclosure comprises a transparent area (61 , 62).

17. Device according to any one of claims 1 -16, characterized in that the upper boundary (20) of the enclosure comprises a sensor for detecting the popula-

35 tion of parasitic eaters in the enclosure (6).

18. Device according to any one of claims 1 to 17, characterized in that the upper boundary (20) of the enclosure is detachable, alternatively hinged to the enclosure side (16).

19. Device according to any of claims 1 -18, characterized in that the sides (16) of the enclosure, at a distance below the openings (24, 26) but above the bottom (14) of the enclosure (6), comprise a row of holes (88) said holes has a diameter that does not allow passage of the parasite eaters.

20. Device according to any one of claims 6-12 and 14-19, characterized in that the wire system for displacement of the slide damper (28) comprises a first wire (36) attached to the first end of the slide damper and a second wire (38) attached to the other end of the sliding damper, said wires are assembled in a collection point (40) at a distance above the upper boundary of the enclosure from which a single third wire (42), detachably connected to the assembly point (40), extends upwards to a pickup system (44, 46, 48, 50, 52), and which assembly point (40) further comprises means for connecting an external lifting unit.

21 . Device according to any one of claims 1 to 20, characterized in that the suspension facilities of the hides (6) are constituted by at least three suspension lines/wires (22) extending between the securing eyes (25) on the outside of the enclosure and connection points located on the side boundary of the float ring point (4) and/or on the side boundary of the fish farm (8).

22. Device according to any one of claims 1 -21 , characterized in that the locking devices (70, 72) of the damper (28) are interconnected by a fourth wire

(76), in the center of which, a fifth wire (78) is attached, said fifth wire (78) being attached to a holding/locking mechanism (86) on the side boundary of the floating ring (4) or on the side boundary of the fish farm (8). 23. Device according to any of claims 1 -22, characterized in that the upper boundary (20) of the containment is held in position by at least one vertically oriented pin (90) comprising a through going opening (94) for receiving a locking bolt (96), said opening (94) is positioned so that the upper boundary (20) when the transverse bolt (96) is located in the through opening (94) is pressed against the walls (16, 18) of the enclosure.

24. Device according to any one of claims 1 -23, characterized in that the enclosure, together with the associated joints, wires and suspension system, are made in a plastic material approved by the food authorities and stainless acid- proof steel approved for food production.

25. Method for improving the efficiency of the control of salmon lice a basin (3) in fish farms, in particular fish farms on the territorial sea, characterized by the following process steps;

-application of a population of parasite eaters and water in one or more shells (6) according to any one of claims 1 -18,

-application of a plurality of shells (6) evenly distributed over the surface of a pool (3) in the fish farm, and in different depths within the range of 0.5 to 10 meters, typically 1 to 8 meters, and preferably 3 to 6 meters,

-displacement of the slide dampers/gates (28) to the passive position whereby the openings in the enclosure are free to pass by the parasite eaters.