United States Patent (19) 11 Patent Number: 5,412,903 Zemach Et Al
Total Page:16
File Type:pdf, Size:1020Kb
O US005412903A United States Patent (19) 11 Patent Number: 5,412,903 Zemach et al. (45) Date of Patent: May 9, 1995 54). SEA CAGE FISH FARMING SYSTEM 4,244,323 1/1981 Morimura ............................. 43/102 75) Inventors: Shalom Zemach, Kfar Yona; Yitzhak Primary Examiner-Kurt Rowan Farin, Ganei Tikva, both of Israel Attorney, Agent, or Firm-Mark M. Friedman 73) Assignee: Metal Yglem Vashkoht Ltd., Tel 57 ABSTRACT V1V, Israe A fish cage system, which includes a fish cage having (21) Appl. No.: 197993 one or more cables connected to it. The fish cage and 22 Filed: Feb. 17, 1994 cable(s) have a combined buoyancy which is such that 6 at least a portion of the fish cage is normally located at s 8 o was a a a - - - - - - - as a a a AOK34: or above the water surface. The cable(s) are connected 58) FiField fa off Searchsearch ......................- - - - - - - - - - - - - - - - - - - - - 43/103,103s s 43. 76 4 s combinedto a sinker buoyancy whose weight of the isfish sufficient cage cable(s). to overcome The sinker the is also connected to a second cable which is connected (56) References Cited to a buoy. The buoy contains a winch for alternately U.S. PATENT DOCUMENTS shortening8 and lengtheningg g the effective length of the 1903,276 3/1933 Y 43/102 second cable so as to alternately allow said fish cage to 3,494,064s1 W/ 2/1970 Steina3a ....... ................................... ... float or to submerge. 4,092,797 6/1978 Azurin .................................. 43/102 4,147,130 4/1979 Goguel .................................. 43/102 11 Claims, 4 Drawing Sheets 4477 aaZZZZZZ U.S. Patent May 9, 1995 Sheet 1 of 4 5,412,903 21 S As 2 f FIG.1A PRIOR ART 12 A 3. ss S t & S Ot 2 FIG 1B Nu PRIOR ART U.S. Patent May 9, 1995 Sheet 2 of 4 5,412,903 FIG.2 PRIOR ART U.S. Patent May 9, 1995 Sheet 3 of 4 5,412,903 N N N U.S. Patent May 9, 1995 Sheet 4 of 4 5,412,903 Z|| |— 5,412,903 1. 2 to a certain depth when desired, e.g., prior to the onset SEA CAGE FISH FARMING SYSTEM of a storm, to avoid cold surface water and/or surface ice in winter and hot surface water in summer, or to FIELD AND BACKGROUND OF THE avoid various toxic contaminants, such as toxic plank INVENTION ton blooms or an oil spill. The present invention relates to systems for farming One such system is the Trident (Trademark) Sea fish in cages and, more particularly, to fish farming Cage System marketed by Innovation & Development systems having a cage which can be submerged and Partners Inc. of Nepean, Ontario, Canada. The Trident refloated as desired. system, shown schematically in FIGS. 1a and 1b, in Considerable efforts have been made in an attempt to 10 cludes a spherical cage 10 and a mooring system. The supply the rapidly increasing worldwide demand for mooring system includes a large mooring anchor 11 fish protein. In addition to increasingly sophisticated through which the mooring cable 12 is led (apparently open sea fishing, a significant fraction of the fish on the through a suitable pulley, or similar mechanism, which market today are raised and harvested using modem is not shown in the figures) to a modified crown buoy 14 aquaculture techniques. Various fish farms have been 15 and thence to the second mooring anchor 16. Tension successfully operating in large man-made pools. How on mooring cable 12 is maintained by the buoyancy of ever, these farms are expensive to build and operate and crown buoy 14 which includes two chambers. Under do not always make it possible to reproduce optimal normal conditions, the lower chamber of crown buoy conditions for the growth of the fish. 14 provides permanent flotation designed to tension More recently, fish farming has been increasingly 20 mooring cable 12 so as to submerge the floating cage 10 carried out in large cages which are made to float near to the desired degree (FIG. 1a). In this condition, the or at the water surface just offshore (hereinafter "near upper chamber of crown buoy 14 remains completely shore') in seas, lakes or other natural bodies of water. A fish cage system includes one or more large cages filled with water. When it is desired to fully submerge which are typically constructed of a rigid frame of some 25 cage 10, water is blown out of the upper chamber of suitable shape and covered by netting which allows crown buoy 14 using compressed air which greatly water to flow freely into and out of the cage but which increases the buoyancy of crown buoy 14 causing it to is of sufficiently fine mesh as to retain the fish inside the rise and to submerge cage 10 to a predetermined depth Cage. (FIG. 1b). The advantage of such fish cage systems is that they 30 Another system is the Atoll 250 marketed by Aqua do not take up scarce real estate and do not require the var of France. A portion of the Atoll 250 system is building of an expensive pool. Furthermore, the water depicted schematically in FIG. 2. Here, as in the Tri conditions (e.g., salinity, temperature, oxygen content, dent system described above, a number of large moor and the like) approximate natural conditions in the open ing anchors 20, 22 and 24, are used and are provided body of water and may be more optimal for the growth 35 with pulleys 26, 28 and 30 through which one or more of the fish than conditions simulated in man-made on mooring cables 34 can move. A buoy 32 is provided to shore pools. alternately take in and release mooring cable 34 which, While the nearshore deployment of such fish cages is in turn, determines the position of fish cage 36. convenient in terms of accessibility, such deployment A disadvantage of both systems is that they use large suffers from certain disadvantages. As nearshore aqua 40 permanent mooring anchors which do not allow the culture develops there is an increasing shortage of qual system to be easily redeployed in other locations as the ity sites in which to locate additional cages. Many sites need arises. Furthermore, each of the systems requires suffer from oxygen depletion caused by fish waste and pulleys or similar mechanisms located near the perma uneaten fish food as well as from industrial, agricultural nent mooring anchors near the sea floor. Such devices and domestic runoffs from the nearby shore. 45 typically require expensive maintenance, involving the It is therefore often advantageous to avoid onshore services of skilled divers. The need to access the mecha locations and to locate the cages farther offshore, in nisms near the sea floor puts a practical limit on the areas which are not adversely affected by runoffs and maximum depth at which such systems can be usefully where the greater water circulation serves to dilute fish deployed. farm wastes. 50 Typically, such systems are not deployed in waters However, locating fish cage systems in locations which are deeper than about 30 meters. While such which are remote from the shore poses certain prob depths may be sufficient in some circumstances, in other lems. Chief among these is the need to ensure the sea cases it may be desirable to lower a fish cage to a greater worthiness of the fish cage system in conditions, such as depth. Furthermore, it may, in some cases, be desirable large waves and strong winds during storms, which 55 to deploy fish cages in waters which are considerably may be much more severe than those experienced by deeper than 30 meters, without regard to the depth to nearshore structures. which it is desired to submerge the cage. Furthermore, it is known that during storms when There is thus a widely recognized need for, and it the water near the water surface is particularly turbu would be highly advantageous to have, a fish cage sys lent, fish, which normally spend most of the their time 60 tem which would be easily deployed in waters of virtu near the water surface where the supply of oxygen is ally any depth, which would allow the fish cages to be most abundant, tend to temporarily relocate themselves submerged in a controlled manner to virtually any away from the surface to depths where the water is depth and which would be easily and readily rede relatively unaffected by the storm and thus avoid dam ployed to other locations. age and stress to themselves. 65 To minimize or eliminate damage to both the fish and SUMMARY OF THE INVENTION the cages, several fish cage systems have been devel According to the present invention, there is provided oped which make it possible to submerge the fish cage a fish cage system, comprising: (a) a fish cage including 5,412,903 3 4 at least one fish cage cable of fixed length connected to the fish cage, the fish cage and the fish cage cable hav DESCRIPTION OF THE PREFERRED ing a combined buoyancy such that at least a portion of EMBODIMENTS the fish cage is located at or above the water surface The present invention is of a fish cage system which when no external forces are exerted upon the fish cage 5 can be used to grow fish in a body of water of virtually or on the fish cage cable; (b) a displaceable sinker con any depth and which gives the ability of submerging the nected to the fish cage cable, the weight of the sinker fish cage to virtually any desired depth.