A FARMING ENCLOSURE FOR FISH AND THE LIKE

Abstract: Farming enclosure saving much work for fish farmers when net cages (4a, 4b) in a plant at sea are to be exchanged and cleaned. In connection with a farming enclosure for fish or marine animals, comprising a supporting structure that is provided at the water surface (2a) and to which a net (4) is secured for forming one or more net cages (4a, 4b) forming one or more dwelling zones under water for the fish, means (5, 6, 7) are provided according to the invention, which serve to exchange net (4) while the fish dwells in said net cages (4a, 4b). In an embodiment of the invention a net reel (5) is used at each end of the structure. Said net reels (5) serve for alternating reeling in and reeling off net (4) along the area of the dwelling zones (4a, 4b) of the fish, at the same time as the net (4) is rinsed in the area of the net reels (5). In this manner clean net (4) for the cages (4a, 4b) is always stored and the cages can be exchanged without the fish (2b) having to be moved. To prevent that the net is pulled up to the surface (2a) in the areas where it forms net cages (4a, 4b) the structure comprises guide means (6) mounted on adjustable slides (7). The structure comprises a portion (1, 2) extending down into the sea in the net area to suppress wave movement and prevent foreign bodies and ice cold water from penetrating into the net cages (4a, 4b).

Description: A farming enclosure for fish and the like The present invention relates to a farming enclosure for fish or marine animals, comprising a supporting structure provided at the water surface, to which structure a net is secured for forming one or more net cages constituting one or more dwell¬ ing zones under water for the fish. Such farming enclosures require maintenance and overhaul irre¬ spective of how the supporting structure is designed. Due to the fact that most plants are provided in sea water the net will foul, and unless the net cages are exchanged the meshes of the net will be completely clogged. This prevents the water flow through the dwelling zones of the fish and the con¬ sequences may be lack of oxygen for the fish, resulting in dis¬ ease and/or death of the fish. One method of reducing such fouling of the net involves impreg¬ nating said net with various chemical compounds. Impregnation represents considerable expense to the farmer, and chemical compounds preventing fouling by algae in some cases may have a detrimental effect on the environment of the fish. Another method of keeping the nets clean is to exchange the nets at certain intervals. It is, however, very demanding to exchange net cages in the present farming systems, and it will cause strain for the fish, because the fish will have to be moved to another net during the cleaning process. This will re¬ sult in loss, because of increased demand for labour, loss in efficiency, and reduced production in the plant. Another problem of the present farming enclosures is that they have a structure that is too weak to withstand storm, ice- covering, and foreign bodies in the water. In practice, foreign bodies often penetrate below the buoyancy members damaging the net or destroying both the buoyancy member and the net. In Northern Norway ice-covering of the plant is a considerable problem to farmers of edible fish. Furthermore, the floating structures of the present farming en¬ closures are not very mobile. This impedes work with moving and mooring the farming enclosures, e.g. . if fish is to be treated against disease, or slaughtered. It is an object of the present invention to eliminate the above mentioned disadvantages. This object is achieved by a farming enclosure of the kind ment¬ ioned above which according to the invention is characterized in that saidfarming enclosure comprises means serving to exchange net while the fish dwells in the net cage or cages. With the 'new kind of farming enclosures the above mentioned problem of net fouling is avoided the net of the cages being cleaned whenever it is necessary. Said means for exchanging net comprise a first and a second reel of net, each provided at one end of the farming enclosures said net reels serving for alternating reeling up and reeling off net along the area of the dwelling zones of the fish. The net reels may be operated by motor or wave power, and the motive pow_er can be controlled manually or automatically. In the areas of ' the net cages, i.e. the dwelling zones of the fish, adjustable guide means are provided for adjusting the cage depth and for guiding the net between exchange means. Said guide means may be somewhat resiliently mounted to balance tension in the net cages, and they are also provided with individual adjusting means. ith such a mechanism it will be a simple matter to change the net without having to move the fish to another net cage. The structure also comprises cleaning means for the net, preferably in the area of the net reels. In the same area collecting means may be provided for the waste removed from the net. The structure may be of a kind permitting the net to be pulled from one side of the plant to the other with a velocity of 2-3 m/hour. On the bottom of the net gripping means may be mounted to remove dead fish from the net bottom. Beneath said reels nozzles may be mounted which continuously rinse the net. In order to protect the net in the water surface area said net is covered by a portion of the supporting structure. This port¬ ion of said structure protects the net and the net cage or cages resp. , not only against waves, but also against foreign bodies in the sea and against cold surface water. The sides of the farming enclosure may, e.g. be submerged approximately 1.25 m below the water surface and this portion of the supporting structure may have a bow profile, preferably at both ends. Such a bow shaped and net protecting structure will also simplify moving the entire structure from one place to another, which is suitable if several farming enclosures are connected to larger assemblies. The exchangeable net is preferably provided in a supporting structure forming a floating unit with suitable access paths around the separate net cages. It is important that access paths and feeding stations are. wide, permitting special feeding carriages to be used. This contributes to improved working conditions and to a safer work-place. The floating structure can also be provided with a roof, which may be advantageous for outdoor plants, especially in the cold season. The invention will be disclosed in more detail below with reference to the drawing showing an embodiment of the farming en¬ closure according to the present invention. Figure 1 is a plan view of an embodiment of a farming enclosure according to the present invention. Figure 2 is a side elevation of the farming enclosure according to Figure 1. Figure 3 is a sectional view of the farming enclosure shown in Figure 1 and 2. Figure 4 is a diagrammatic top view of an embodiment of four farming enclosures, each comprising two net cages arranged side- by-side. As will appear from Figures 1, 2, and 3, showing an embodiment of a farming enclosure for fish or marine animals according to the present invention, the plant comprises a supporting structure provided at the surface of the sea and to which a net is secured for forming one or a plurality of net cages where fish or other marine animals can dwell under water. Said supporting structure comprises a buoyancy member compris¬ ing a plurality of'pontoons 1 in the shape of tubes with a bow profile at each end. Tight walls 2 of plates are welded to the pontoons and said walls together with said pontoons 1 extend approximately 1.25 m below the water surface 2a. This combined tube and plate structure will contribute to keep cold surface water from the area that is limited by said walls 2, at the same time as the structure ensures the possibility of pumping warmer water from deeper layers of the sea. Such a structure can improve the breeding environment of the fish 2b dwelling in the farming enclosure, as well as preventing fish from dying due to cold surface water. The pontoons 1 with walls 2 are protected by fenders 3 so that the floating structural units can be assembled to larger units. Inside the area limited by said pontoons 1 and walls 2 a net 4 is extended to form two net cages 4a and 4b, said net 4 being specially designed to withstand stretch loads and to ensure good flow through said net cages or dwelling zones of the fish 2b. At each end of the structure there are mounted members to displace the net 4 at the same time as net cages 4a and 4b are maintained intact without disturbing the fish. Thus, the net can be cleaned or changed without the necessity of moving the fish to another net cage. In the shown embodiment the members for changing the net are shaped as net reels 5 provid¬ ed at each end of the plant, said reels 5 serving to alternat¬ ely reel up and reel off net along the area of the dwelling zones of the fish. When the net reels 5 turn there will be tension on the net. In order tθs keep the net 4 in place form¬ ing suitable net cages 4a and 4b guide rolls 6 are mounted. Said guide rolls 6 may be spring loaded by the aid of slide rods 7, the length of said rods 7 being adjustable for adjust¬ ment of the net cage depth, at the same time as the resilient mounting will balance the tension in net cages 4a, 4b. The net material, may suitably be enlarged at the places where the load is expexted to be greatest. In the shown embodiment the structure is adapted for the net reels 5 to be able to handle two cages 4a and 4b. To ensure that the net material 4 is not damaged during displacement and is, at the same time, kept in place further upper guide rolls 10 and 11 are mounted, and in the area between net cages 4a and 4b an additional roll 12 is provided and serves to take care of said functions. At its upper edges the net is rein¬ forced by a rope 15, which is, in turn, in connection with said guide rolls 10. The structure is provided with gangways 8 and 17 and spacious working decks 13 to ensure good access to the structure. The units may also be provided with a roof 21 which will addition¬ ally improve working conditions. A cleaning area 9 is preferably provided in the area of the net reels 5. Here it will be possible to clean the net 4 as it is pulled up from the sea area and is wound onto the net reels 5, e.g. manually by high pressure washing 16 or by the aid of a stationary washing device on working deck 13. Near the washing area 9 tanks may suitably be provided for collect¬ ing washing sludge, e.g. algae and other kinds of waste. The tanks may be ' placed at the ends of the structure, and the sludge can be removed when necessary, either by dumping in the sea or by being transferred to other containers. The length of the net material per se should be at least twice the length provided in the water, so that there is al¬ ways a clean half reeled up. In this manner the net can be cleaned and mended when this is necessary without the fish being disturbed or moved. For further protection of the fish a bird net 20 may be pro¬ vided which will prevent birds from reaching the net cages 4a and 4b with the fish 2b. At each end of the structure a belaying cleat 14 is provided for a mooring hawser and, if desired, a towline. In the area of the mid net rolls or guide rolls 12 a feeding station 18 is provided, which may comprise a cross gangway with a transport path 19 taking the load of a carriage or a trolley with feed. In Figure 4 an embodiment of a plant is shown comprising four pontoon members, e.g. of the kind disclosed above in connection with Figures 1-3. Each farming enclosure comprises two net cages 4a,4b, and each farming enclosure can be towed off rapidly in case of disease or for slaughtering the fish. The shown struct¬ ure permits simple mooring to a jetty 25 or, if desired, to a waterside 26, as well as to other breeding baskets. Because of its boat shape the separate farming enclosures will be simple to moore, and they can be towed and displaced in a rapid and efficient manner.

Claims: CLAIMS: 1. A farming enclosure for fish or the like comprising a supporting structure that is provided at the surface of the sea (2a) and to which a net (4) is secured for forming one or more net cages (4a, 4b) that constitute one or more dwelling zones below water for fish (2b), c h a r a c t e r i z e d i n that said farming enclosure comprises means (5, 12, 6,7) serving to exchange net (4) while the fish stays in the net cage(s) (4a, 4b). 2. A farming enclosure as defined in claim 1, c h a r a c t e r i z e d i n that the exchange means comp¬ rise a first and a second net reel (5) provided one at each end of the farming enclosure, and that said net reels (5) serve for alternate reeling in and reeling off net (4) along the area of the dwelling zones (4a, 4b) of the fish. 3. A farming enclosure as defined in claim 1 or 2 , c h a r a c t e r i z e d i n that said net reels (5) are operated by the aid of motor or wave power, and that the motive power can be controlled manually or automatically. 4. A farming enclosure as defined in one of claims 1-3, c h a r a c t e r i z e d i n that in a structure comprising a plurality of net cages (4a,4b) arranged in series, one or more guide rolls (12) for a displaceable continuous net (4) are provided in the area between net cages (4a, 4b). 5. A farming enclosure as defined in one of claims 1-4, c h a r a c t e r i z e d i n that adjustable guide means (6,7) for adjusting the cage depth and guiding the net (4) between exchange means (5) are provided in the areas of the net cages (4a, 4b), i.e. the dwelling zones of the fish (2b). 6. A farming enclosure as defined in claim 5, c h a r a c t e r i z e d i n that said guide means (6) are mounted somewhat resiliently for balancing tension in said net cages ( 4a,4b), and provided with individual adjustment means (7). 7. A farming enclosure as defined in one of claims 1-6, c h a r a c t e r i z e d i n that the structures comprise cleaning means (9,16) for the net (4), preferably in the area of the net reels (5), and " that collecting means for the waste removed from the net (4) are provided in the same area. 8. A farming enclosure as defined in one of the preceding claims, c h a r a c t e r i z e d i n that gripping means are mounted on the net (4) to serve for simple transport of dead fish from the dwelling zones (4a,4b) of the fish. 9. A farming enclosure as defined in one of the preceding claims, c h a r a c t e r i z e d i n that the windable net (4) is covered in the area of the water surface (2a) by a portion (1,2) of the supporting structure protecting the net (4) especially the net cage(s) against waves, foreign matter in the sea, and cold surface water. 10. A farming enclosure as defined in claim 9, c h a r a c t e r i z e d i n that the portion of the supporting structure covering the net (4) in the area of the water surface (2a) is shaped as a bow profile, preferably at both ends. 11. A farming enclosure as defined in one of the preceding claims, c h a r a c t e r i z e d i n that the exchange¬ able net (4) is provided in a supporting structure constituting a floating unit with suitable access paths (17,19,13) around the individual net cages (4a,4b), buoyancy being provided by pontoons (1) made from a rigid and durable material, e.g. metal, plastic, or concrete.

Inventors: ESAIASSEN EINAR TORE, FREDRIKSEN SIGMUND, ESAIASSEN, EINAR, TORE, FREDRIKSEN, SIGMUND
Applicants: SENJA AQUASERVICE AS
Application year: 1986
Main classification: A01K61
IPC codes: A01K61, A01K63