Aquaculture system

Abstract

Method and apparatus for the aquaculture of aquatic, non-air breathing, carnivorous animals, wherein a generally enclosed body of water is established, and aquatic non-air breathing, carnivorous species to be reared is disposed in said body of water, a filter-feeding aquatic non-air breathing species is also disposed in said body of water, and an aqueous euphotic zone containing phytoplankton is established in said body of water; the excreta from said carnivorous and filter-feeding species providing nutrients to said phytoplankton, said phytoplankton at least in part providing the food for said filter-feeding species, and said filter-feeding species at least in part providing the food for said carnivorous species. The water in said enclosed body is circulated so as to move water from below said euphotic zone to within said euphotic zone so that settling nutrients and phytoplankton are returned to the euphotic zone for maximum photosynthetic production of protoplasm in the system, and to avoid eutrophication in the lower levels of the body of water resulting from phytoplankton death and bacterial action on the nutrients. Such circulation may, according to the invention, be provided by energy from sea water, either from its higher specific gravity than fresh or brackish water, or from tidal action, or both. Sea water is utilized according to the present invention in combination with fresh water to provide brackish water at least in said euphotic zone for optimum growth conditions of all three principal life forms, the phytoplankton, the filter-feeding species, and the carnivorous species. A fresh water lens or blanket may be spread over the top of the more dense brackish water during the cold season to provide a "greenhouse effect" maintaining the body of water within the desired temperature range for the growth cycle of the system.

I claim: 
     
       1. A method of aquaculture of a carnivorous aquatic non-air breathing species in a generally enclosed body of water, which comprises establishing an aqueous euphotic zone containing phytoplankton in said body of water above an aqueous bottom zone, providing nutrients in said euphotic zone sufficient to cause growth of phytoplankton .[.at a rate of at least about 2 grams of carbon per square meter per day.]., disposing a filter-feeding aquatic non-air breathing species in said body of water which will feed upon said phytoplankton and upon which said carnivorous species will feed, introducing said carnivorous species into said body of water, the excreta from said carnivorous and filter-feeding species providing at least a portion of said nutrients to said phytoplankton, said phytoplankton at least in part providing the food for said filter-feeding species, and protoplasm of said filter-feeding species at least in part providing the food for said carnivorous species, establishing a waterdriven upwelling movement of water in said body of water from within said bottom zone by introducing water into said bottom zone such that water in said bottom zone is moved upwardly to within said euphotic zone to recirculate nutrients from the bottom zone to the euphotic zone for reconversion therein by the phytoplankton, thereby generating oxygen and eliminating the toxicity of excreta to said carnivorous species, removing water from said euphotic zone near the surface thereof, and harvesting members of said carnivorous species which have grown to a desirable size. 
     
     
       2. The method of claim 1, wherein the young of carnivorous fish species are introduced into said body of water. 
     
     
       3. The method of claim 2 wherein the young of Atlantic salmon are introduced into said body of water. 
     
     
       4. The method of claim 1, which includes some ration feeding of said carnivorous species in addition to the feeding thereof on protoplasm of the filterfeeding species. 
     
     
       5. The method of claim 1, wherein said upwelling movement of water is at least in part caused by tidal action. 
     
     
       6. The method of claim 1, which comprises adding makeup water to said body of water, and removing water from an outlet zone of said body of water that is generally isolated from said upwelling movement of water. 
     
     
       7. The method of claim 6, wherein said upwelling movement is caused by having said makeup water of a different salinity than the water in said euphotic zone, and creating a pressure head in the addition of said makeup water that causes said upwelling movement. 
     
     
       8. The method of claim 1, wherein makeup water is added to said body of water including a sea water component and a fresh water component, said components being mixed to provide said brackish water. 
     
     
       9. The method of claim 8, wherein said brackish water has at least about 3 o/oo saline content. 
     
     
       10. The method of claim 9, wherein said brackish water has a saline content that is approximately isotonic for said carnivorous species. 
     
     
       11. The method of claim 8, which includes establishing a discrete fresh water insulating layer on top of said brackish water so as to raise the temperature in said body of water. 
     
     
       12. The method of claim 11, wherein said insulating layer is adjusted on a seasonal basis. 
     
     
       13. The method of claim 8, wherein brackish water is removed from said body of water. 
     
     
       14. The method of claim 13, wherein a forebay is associated with said body of water, said sea water component being moved as a lower zone in one direction through said forebay and then introduced into said body of water, and said brackish water that is removed from said body of water being moved as an upper zone in a direction generally opposite to said one direction through said forebay and then into the ocean. 
     
     
       15. The method of claim 14, which includes establishing a discrete fresh water insulating layer on top of said upper zone of said forebay so as to raise the temperature in said forebay. 
     
     
       16. The method of claim 8, wherein said sea water component is introduced into a lower zone in said body of water and said fresh water component is introduced into an upper zone in said body of water so as to create discrete upper and lower zones in said body of water with said lower zone having a higher salinity than said upper zone. 
     
     
       17. The method of claim 16, wherein said upper zone is included in said euphotic zone. 
     
     
       18. The method of claim 16, wherein the salinity difference between said lower and upper zones is at least about 0.1 o/oo saline content. 
     
     
       19. The method of claim 16, wherein said lower and upper zones are caused to move in generally opposite directions in said body of water. 
     
     
       20. The method of claim 19, wherein a brackish water outlet region is established, and wherein said upwelling movement is principally of water from said lower zone into said upper zone in a region of said body of water remote from said outlet region, and wherein brackish water is removed at said outlet region from said upper zone. 
     
     
       21. A system for the aquaculture of a carnivorous aquatic non-air breathing species, which comprises an enclosure having a body of water therein, an aqueous euphotic zone containing phytoplankton in said body of water above an aqueous bottom zone, a carnivorous species in said body of water, a filter-feeding species in said body of water which will feed upon said phytoplankton and upon which said carnivorous species will feed, the excreta from said carnivorous and filter-feeding species providing nutrients to said phytoplankton, said phytoplankton providing food for said filter-feeding species, said filterfeeding species providing food for said carnivorous species, water circulating means in said enclosure including water-driven means for introducing water into said bottom zone such that water in said bottom zone is moved upwardly causing an upwelling movement of water in said body of water from below said euphotic zone to within said euphotic zone to recirculate nutrients from said bottom zone to said euphotic zone for reconversion therein by the phytoplankton, thereby generating oxygen and eliminating the toxicity of excreta to said carnivorous species, and means for removing water from said euphotic zone near the surface thereof. 
     
     
       22. A system as defined in claim 21 wherein said water circulating means comprises, at least in part, sea water inlet means for introducing sea water into said enclosure. 
     
     
       23. A system as defined in claim 22, wherein said sea water inlet means comprises tidal inlet means whereby tidal movement at least in part causes upwelling. 
     
     
       24. A system as defined in claim 21, wherein said body of water includes lower and upper brackish water zones of respectively higher and lower salinities. 
     
     
       25. A system as defined in claim 24, in which said water circulating means causes movement of said upper and lower brackish water zones generally in opposite directions in said enclosure. 
     
     
       26. A system as defined in claim 25, wherein said circulating means comprises at least in part, sea water inlet means for introducing sea water into said lower brackish water zone. 
     
     
       27. A system as defined in claim 26, wherein said circulating means comprises, at least in part, fresh water inlet means for introducing fresh water into said upper brackish zone. 
     
     
       28. A system as defined in claim 21, wherein said body of water in said enclosure is principally brackish water having an upper boundary, and fresh water inlet means in said enclosure proximate said boundary for flowing a discrete fresh water insulating layer on top of said brackish water boundary so as to raise the temperature in said brackish water. 
     
     
       29. A system as defined in claim 28, which includes means on said enclosure for adjusting the thickness of said fresh water insulating layer. 
     
     
       30. A system as defined in claim 21, which includes a forebay having a lower sea water zone and an upper brackish water zone, and having respective sea water and brackish water inlets to said zones, means connecting said forebay sea water zone with said enclosure to provide a sea water component to said body of water, fresh water inlet means in said enclosure providing a fresh water component to said body of water, means for mixing said sea water and fresh water components in said body of water so that said body of water is principally brackish water, and brackish water outlet means in said enclosure providing brackish water to said forebay brackish water inlet. 
     
     
       31. A system as defined in claim 30, which includes fresh water inlet means to said forebay proximate the upper boundary of said brackish zone of the forebay for flowing a discrete fresh water insulating layer on top of the brackish water in the forebay so as to raise the temperature in the forebay. 
     
     
       32. A system as defined in claim 21, wherein said body of water is divided into a sink region and a main rearing area by a barrier that is at least in part foraminous, and sea water inlet means proximate the bottom of said sink region to provide a flow of sea water upwardly in said sink region and thence through said barrier and into said main rearing area; water oultet means on said enclosure and generally isolated from said upwardly flowing sea water for outflow from proximate the surface of the body of water, said carnivorous species comprising a carnivorous crustacean species located in said main rearing area, and said filter-feeding species comprising bivalve species located at least in part in said sink region. 
     
     
       33. A system for the aquaculture of a carnivorous aquatic non-air breathing species which comprises an enclosure having a body of water therein, an aqueous euphotic zone containing phytoplankton in said body of water above an aqueous botton zone, respective downflow and upflow mixing chimneys remotely spaced from each other in said body of water, sea water inlet means for introducing sea water into said downflow mixing chimney to cause mixing of sea water with water from said euphotic zone to provide brackish water and disposition of same in said lower zone, fresh water inlet means for introducing fresh water into said upflow mixing chamber to cause mixing of fresh water with brackish water from said lower zone and disposition of the resulting mixture in said euphotic zone, whereby brackish water in said bottom zone is caused to move generally in the direction from said downflow chimney toward said upflow chimney, and water in said euphotic zone is caused to move generally in the direction from said upflow chimney toward said downflow chimney, and means for removing water from the euphotic zone near the surface thereof at a position remote from said upflow chimney.