Note: Descriptions are shown in the official language in which they were submitted.
3 ol ~
FIEL~ OF THE INVENTION
The present invention relates to apparatus for use in
aquaculture of fish and other marine organisms and more
particularly to a generally spherical, submersible cage
system for culturing aquatic animals adapted for use in
harsh environments.
BACKGROUN~ OF THE INVENTION
Commercial scale floating cage systems for the
cultu~ing of fish and other aquatic animals are known
although the industry is relatively underdeveloped in terms
of practical design and operational experience.
Accordingly, numerous cage designs have been proposed, none
of which has proven completely successful in terms of cost,
durability, biological compatibility and economic viability.
Most designs, including the present one, share a number of
features in common, including a buoyant framework defining
the cage, a net or perforated panels supported on the inside
or outside of the frame to deEine an enclosure, means to
support the cage for rotation about a central axis so that
individual surfaces or port:ions of the net can be
periodically exposed to ambient air eor cleaning, repair or
replacement and a mechanism for submerging the cages in the
event O:e v:Lolent weather, ice, lethally cold water, toxic
bloom and other surface hazards.
~ M~y_OF r~l~.. l~Y~ Q~
It :is an object of the present invention to provide an
economically and biologically viable submersible cage system
for the culturing of fish and other aquatic animals that
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obviates and mitigates from the disadvantages of the prior
art.
According to the present invention, then, there is
provided a submersible cage system for cultivating aquatic
animals comprising a rigid frame, a net supported by said
rigid frame to define a water-permeable enclosure for said
aquatic animals, means for rotatably supporting said rigid
frame in a ~ully or partially submerged condition, and means
for anchoring said frame in a Pixed position in a marine
environment, wherein said rigid ~rame defines a geodesic
sphere.
According to a further aspect oP the present invention,
there is also provided in a submersible cage system Por
culturing aquatic animals, said system inciuding a rigid
frame for supporting a net which defines in combination with
said frame an enclosure for said aquatic animals, the
improvement wherein said rigid frame is a geodesic sphere.
BRIEF ~ESCRIP~N _F T~IE ~AWINGS
Preferred embodiments of the present invention will now
be described in greater deta:Ll and will be better understood
when read in conjunctLon w.Lth the following drawings in
which:
Figure :L is a front elevational view of a geodesic cage
comprising part of the present cage system;
Figure 2 is a perspective view of the present system
with the cage in a partially submerged condition;
Figure 3 is a perspective view of the present system in
a Pully submerged condition;
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Figure 4 is a perspective view of a flotation chamber
forming part of the present system;
Figure 5 is a plan, partially sectional view of the
flotation chamber of Figure 4; and
Figures 6, 7 and 8 are perspective views of a modified
system comprising a plurality of the cages of Figure 1 in a
partially submerged condition.
Figure 9 is an isometric view of a connector for a
geodesic cage.
Figure 10 is an isometric view of a connector for a
geodesic cage in an alternate embodiment.
Figure 11 is an elevation view oE a geodesic cage.
Figure 12 is a plan view of a geodesic cage.
Figure 13 is a detail of an exemplary pipe element of
a geodesic cage.
Figure 14 is a schematic illustration of harvesting
using the submersible cage system.
Figure 15 is a schematic illustration oE mortality
removal using the submersible cage system.
Figure 16 is an isometric view of a portion of a
submersible c,age system in an alternate embodiment~
Figure 17 is an illustration o feeding using the
submersible cage system.
Figure 18 is a plan view oP a portion of a submersible
cage syetem in an alternate embodiment.
Figure 1~ is a view along the equator of a geodesic
cage illustrating the rotation system of a submersible aage
system.
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Figure 20 is a view along the axis of a geodesic cage
illustrating the ro-tation system of a submersible cage
system.
Figures 21 and 22 are isometric views o~ connectors for
the south and north apexes of a geodesic cage.
Figure 23 is a detail view of a connector for the north
apex of a geodesic cage.
Figures 24, 25 and 26 are schematic ~llustrations of
alternative mooring systems for a submersible cage system.
DESCRIPTION OF THE PREFER~ED EMBODIMENTS
With reference to Figure 1, it has been found that the
use of a geodesic sphere provides a markedly superior frame
compared to previous cage constructions in terms of riyidity
and strength, weight, cost of construction, ease of field
assembly and inherent protection against predation by birds,
seals and other predatory fauna.
Cage 1 comprises a frame 2 consisting of a plurality of
five or six-point connectors 4 that anchor the ends of
tubular elements 8 which together define a geodesic sphere
7 typically 40 to ~5 feet in diameter. Larger or smaller
diameter cages are contemplated for some situations.
Elements ~ may advantageously be lengths of stainless steel
or aluminum pipe or some other relatively light, strong and
corrosion-reslstant material.
The st,ructure of ~rame 2 is shown in greater detail in
Figures 9 to 13. ~s shown in Figure 9, pipe elements 8 are
tapered, flattened and crimped at their ends 102. Connector
~ is an extruded hub with a plurality of circumferentially
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spaced longitudinal slots 104 which extend the length of the
connector's outer surface. The cross-sectional shape of
slots 104 corresponds to the cross-sectional shape of ends
102 so that ends 102 are slidably insertable in cooperating
slots 104. Ends 102 and slots 104 are provided with
cooperating teeth 105 so that slots 104 radially retain
pipes 8 after insertion.
As can be seen in Figure 23, the flattened end of pipe
8 is cut at an angle so that pipe 8, when installed in
connector ~, extends at an angle to the axis of connector 4.
The angle is that appropriate for the "curvature" of frame
2 at the point of connection.
A~ial bore 106 extends through connector 4. A threaded
fastener 108 is inserted through bore 106. After ends 102
of each of pipes 8 are slidably inserted into slots 104,
washers 110 are installed on fastener 108 at either end, and
retained by threaded nuts 112. Washers 110 close the ends
of slots 104 preventing any further sliding movement by
pipes ~ which are thus firmly retained by slots 104.
In an alternate embodiment shown in Figure 10l
connector 114 has slots 116 which are larger than the
toothed ends 102 of pipes ~. A high tensile polymer insert
11~ Eits tightly around toothed end 102 and inside slot 116,
so that end 102 together with insert 118 is slidably
insertable into slot 116 and is firmly retained therein.
The use of connector 11~ and insert 11~ facilitates assembly
and disassembly by insulating end 102 from direct contact
with connector 11~ and thereby reducing frictional
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resistance. Inserts 118 also advantageously function to
seal ends 102 of tubes 8 from the corrosive activity o~ salt
water or other corrosive environments.
For use in a salt water environment, marine alloy
aluminum is a preferred material for pipes 8, connectors
~,114 and washers 110, while stainless steel is preferred
for fastener 108 and nuts 112.
Possible alternative shapes for cage 1 include
spherical, oblate spheroid, elliptical, or sausage shaped.
A preferred 8-layer, spherical shape is shown in Figures 11
(elevation view) and 12 (plan view), suitable for exposed
ocean conditions. A sphere with fewer elements 8 can also
be constructed for use in more protected sites. As shown in
Figure 13, elements 8 may be bent at ends 112 to enable the
construction of various cage shapes using connectors 114
having equally spaced slots 116, thus facilitating
manu~acture and assembly. In Figures 11, 12 and 13, the
symbol "\ _ " indicates a bend in an element 8 and its bend
direction.
q'ypical slot arrangements 114a and ll~b are shown in
~igures 11 and 12. In the partLcular geometry illustrated
in Figures 11 and 12, slot arrangement ll~a has six equally
spaced slots (appl;icable eor the rLng Oe connectors at the
equator lL5 and the two rLngs Oe connectors 115a,115b north
and south O:e the e~uator) while slot arrangement 114b has
eight e~ually spaced slots (applicable for the rings o~
connectors 117a,119a adjacent the north and south apexes
117,119).
2 ~ 3 ~ 1
cage 1 is neutrally or pre~erably slightly positively
buoyant. Buoyancy is provi~ed, for example, by sealing
pipes 8 at both ends to provide flotation although excess
~lotation will likely result if all of pipes g are sealed,
depending to a certain extent upon the pipe material used.
Buoyancy may be regulated by perforating evenly distributed
selected ones of the pipes, or by adding symmetrically
distributed weights to the structure. Excess positive
buoyancy is preferably avoided so that in a fully submerged
condition, the cage supports are not subjected to excessive
stress caused by the force of flotation.
However, the innerent buoyancy of cage 1 is preferably
such that when cage 1 is optimally 66% submerged, sufficient
tension is exerted on its mooring cables (described below)
to stabilize the structure in a seaway. Positive buoyancy
may also be obtained by filling the hollow structural
elements with foam.
Cage 1 includes an axle 10 journalled through
diametrically opposed connectors 11 and 12 so that ends 14
and 15 oP the axle extend radially outwardly from the
sphere. The sphere is itselE rotatable with or about axle
10 for cleaning and harvesting purposes as will be described
in greater detail below.
To comp:lete the cage, frame 2 is covered with a taut
net 20 of the appropriate mesh dimensions to retain the fish
within the enclosure so formed.
Preferably, netting of nylon material is used. The
netting is sewed into two half hemisphere sections (not
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illustrated) and continuously reinforced with bolt rope (not
shown) in accordance with standards used for the manufacture
of trawl netting. The netting is then attached to the
inside of frame 2 with a large number of attachments so that
point loads are distributed over a large number of net/~rame
connections. A large number of such connections, together
with the generally spherical shape of the net,
advantageously results in reduced shock load, better load
distribution and higher reliability of the net/frame
connections than if fewer connections are used.
Ends 1~ and 15 of axle 10 each have mounted thereon a
flotation chamber 25, one of these chambers being shown in
greater detail with reference to Figures 4 and 5. Each
chamber can be filled either with air to add the required
degree of buoyancy to cause the cage to rest in a partially
submerged condition at the water's surface 19, or with water
to sink the cage into a more fully or completely submerged
condition in the event of heavy weather, ice or a surface
layer of lethally cold water.
~s shown in Figures ~ and 5, chamber 25 may be
triangular in transverse cross-sectional shape and includes
two mutually orthogonal conduits formed therethrough.
Vertical conduit 36 prov:ides free passage for a cable 30
used to anchor the caye in a Eixed location relative to the
seabed as will be d~scribed below. Horiæontal conduit 28
connects to an umbilical cord 35 extending from the axially
outer end of the conduit to a surface float 45. Umbilical
cord 35 encloses an air hose (not shown) to purge or blow
20~L30~
flo-tation chambers 25 and a food duct (also not shown) to
direct food from a surface tender to the interior of the
cage. The umbilical cord may also include, if necessary, a
reinforcing cable so that the cord is strong enough to moor
the tender. The tender will have both an air pump ~or
blowing chambers 25 and a food pump ~or injecting nutrients
into the cage in predetermined amounts.
Horizontal conduit 28 is formed below the horizontal
centre line of float 25 and includes at its inner end 26 a
bearing 27 which journals a respective end 14/15 of axle 10.
With the majority of the buoyancy provided by chamber 25
located vertically above axle 10, the chamber will be self-
righting and will effectively resist rotation as cage 1 is
itself rotated.
In one embodiment contemplated by the applicant, the
food duct connects to journalled end 1~/15 of a hollow axle
10 for delivery of the food to the interior of the cage
through perforations in that portion of the axle passing
through the cage's center.
Cage 1 is maintained in a fixed position relative to
the seabed by means of cables 30 which pass ereely through
vertical conduits 26 in flotation chambers 25 and which
connect at their lower ends to eixed permanent weights ~2
anchored to the eeabed and at theLr upper ends to a pair of
surface floats ~5. Obviou~ly, cage 1 is free to move up and
down on cables 30 to accommodate either wave motion at the
water's surface or so that the cage can be raised or lowered
along the cables as required.
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The mechanism used to either float or submerge the cage
will now be described with reference to Figures 2, 4 and 5.
As mentioned above, ca~e 1 is slightly positively buoyant
and will therefore remain at the surface of its own
5 volition. Flotation chambers 25 can be purged of water to
add additional buoyancy so that the cage, when at the
surface, is only half submerged which facilitates
maintenance, repair and harvesting of the fish within the
cage. Removing more air from chambers 25 will cause the
cage to remain in an approximately two-thirds submerged
condition which is the normal operating position for fish
culturing. Further air exhaustion from chambers 25 will
cause cage 1 to descend completely below the water's
surface.
Suspended from each of chambers 25 by means of fixed-
length cahles 39 is a counterweight 54. The two
counterweights 54 collectively partially offset the positive
buoyancy of cage 1. Thus, with cage 1 at the surface in a
partially submerged condition, the counterweights will act
as a stabilizing force to dampen wave movement that would
otherwise disturb the fish. When the cage is in a full.y
submerged condition, counterweights 54 will rest on top of
permanent weights 42 and will maintain the cage at a fixed
distance above the permanent weights equal to the length of
cables 39, assumlng of course that chambers 35 are not
purged to the point where the cage assumes negative
buoyancy.
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11
As will be seen most clearly from Figure 3, each
counterweight 54 is formed with a vertical conduit 57 which
freely entrains a respective one of cables 30 for guided
movement of the counterweight up and down along the cable.
Obviously, the economics of cage aquaculture improve
with increased concentrations of fish stocks. Populations
within individual cages can be increased only to more or
less fixed levels, depending upon the species of fish being
cultured, before losses due to problems with feeding, trauma
and disease become excessive. Enlargement of the cages
themselves permits an increase in the si2e of the fish stock
while maintaining densities at acceptable levels, but costs,
and structural and operational difficulties, increase
disproportionately with increasing cage dimensions. The
obvious answer is thereEore to increase the number of cages
per installation. The present system lends itself to this
as shown wi-th reference to Figures 5, 6 and 7.
In each o~ Figures 5, 6 and 7, like elements to those
appearing in the previous figures are identified using lilse
reference numerals. The figures in ~uestion show systems
incorporating 2, 3 and 4 cages, respectively, and as each
system is structurally and operationally similar, reeerence
will be made speciPica:Lly to Figure 7 showing a system
having three cages.
Each cage is mounted on an axle 10. The radially inner
end of each axle is slidably connected to a vertical,
centrally located pylon 75 to permit up and down movement of
the axle as the associated cage is itself raised and lowered
~O~L~30~
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to and from the water's surface. The radially outer end of
each axle is connected to a hoop 68 which circumscribes all
three cages. Advantageously, a radar reflector and beacon
is located at the upper end of the pylon to facilitate
navigation to and from the cages and to prevent collisions
with passing vessels.
In other respects, the three-cage system is
structurally and operationally similar to the one-cage
system described above.
When submerged, the cages will become fouled with a
biomass of material including barnacles, algae and other
marine growths. Cleaning is easily accomplished by
periodically rotating the cages while at the surface to
expose successive portions of the seabed frame and net to
ambient air, causing the biomass to die, dry up and then
blow away in the wind. Heavily encrusted fouling can be
removed by hand or by a pressurized water spray from the
tender.
Some species of fish require that some eree air be
trapped or is capable O:e being trapped within the cage when
fully submerged. This can be accomplished in the present
system by ad~ing an a:ir :lmpermeable membrane in the form of
a cap or dome ~0 to the cage as shown in dotted lines in
F'igure 1. Obviously, when the cage is submerged, it is
rotated into a position with cap 80 at the top thereof
relative to the water's surface.
Methods of harvesting and mortality removal are
illustrated in Figures 1~ and 15 respectively. For
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harvesting, a quarter net 120 is fitted inside cage 1 from
its center to its circumference. By rotating the cage
through one full rotation the fish in cage 1 are harvested.
By using a larger mesh size, the larger fish may be
selectively harvested. For mortality removal, a small net
122 is left permanently attached to the inner circumference
of cage 1. By rotating cage 1 through one full rotation,
dead fish are collected and may be conveniently removed.
Alternate embodiments of the submersible cage system
are illustrated in Figures 16 to 23. Having reference to
Figure 16, cage 131 is substantially the same as cage 1
previously clescribed with the following differences. A
vertically oriented circular track 132 surrounds cage 131 at
its equator, and cage 131 is attached thereto. Cage 131 is
rotated by applying tangential force along track 132.
Mooring cable 134 is attached to car 135 which runs freely
along track ~32. As track 132 and cage 131 are rotated, car
135 moves along track 132 so the position of mooring cable
134 remains substantially stationary while cage 131 rotates.
Track 132 thus eliminates the need for an axle through the
cage, and provides a conveni0nt point of attachment for
mooring cable 134. However, a modi~ied hollow hub connector
136 is provided to which feed hose 138 is pivotably
connectable for supplying nutrients to the fish in cage 131.
Hose 138 remains connected to hub 136 and, except
during feeding, the free end is retained at the surface by
floating buoy 140. As shown in Figure 17, the fish are fed
hydraulically from a service vessel 142 which draws up to
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14
~he cage. A water pump (not shown) in vessel 142
hydraulically forces the fish food below the water through
hose 138 and hub 136. The food pellets 144 are of varying
densities, for example, floating, neutrally buoyant and
sinking, to ensure that all the fish in cage 131, surface,
midcage and bottom dwellers have access to food 14~. The
hydraulic feeding mechanism allows feeding of fish even when
cage 131 is fully submerged.
Having reference to Figure 18, cage 151 is
substantially the same as cages 1 and 131 previously
described with the following differences. Instead of a
vertically oriented circular track 132, cage 151 is
rotatably attached at its north and south apexes to
stabilizer legs 152 and 15~ Cables 156 extend downward and
connect to the ends 158 of rigid spreader bar 160, and
cables 162 connect the ends 160 o~ spreader bar 160 to
mooring cable 164 at grommet 166. Spreader bar 160 is
formed of marine grade aluminum tube filled with foam for
positive or near neutral buoyancy.
An axle which extends through cage 151 is not required,
but axles are provi~ed at the north and south apexes to form
a rotatable attachment of cage 151 to stabilizer legs 152
and 15~. At the south apex, axle 16~ (Figure 19) is rigldly
attaahed to stabilizer leg 15~, and rotatably engages a
special apical hub connector 170 which takes the place, at
this point, of connectors ~ or 11~ described earlier. As
shown in detail in Figure 21, connector 170 is formed oE a
rigid metal sleeve 172 which has a plurality of longitudinal
slots 174 disposed about its outer circumference capable of
slidably receiving the corresponding ends of pipes 8. The
inside of sleeve 172 is circumferentially lined with nylon
bushing 176 which engages axle 168 with a minimum of
frictional resistance.
Similarly, at the north apex axle 178 is rigidly
attached to stabilizer leg 152, and rotatably engages a
special apical hub connector 180. As shown in Figure 22,
connector 180 includes a sleeve 182 with slots 184 for
connection with pipes 8, and nylon bushing 186 for non-
frictional engagement with axle 178. Sleeve 182 is extended
outward and provided with radial spokes 188. Axle 178 has
a hollow inner passage 190 which communicates with the
inside of cage 151 ~or connection to a feeder hose 192.
A rotation system for cage 151 is shown in Figures 19
and 20. Spokes 188 extend radially outward from connector
180 to a hexagonal ring structure 194. Spokes 188 are
rigidly attached to connector 180, and struts 196 reinforce
the attachment of ring 19~ to cage 151, so cage 151 rotates
together with ring 194. Stabillzer leg 152 extends upward
beyond the highest point of ring 194 and mounts a means for
rotationally drivlng rlng 19~. An enclosed, hand cranked,
worm-gear reduct:Lon drive unit 198 drives chain 200, which
in turn drives chain sprocket 202 attached to ring 194.
Guiding roll~rs 20~ are mounted on stabilizer leg 152 at the
upper and lower points of contact with ring 19~ to ensure
smooth rotatio~ ~f cagé 151 relative to stabilizer leg 152.
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16
When cage 151 is optimally 66% submerged, drive unit
198 is above the surface of the water as shown in Figuxe 18.
Once every week or so, or as needed, the aquaculture
operator pulls alongside the cage in a service vessel
normally under calm conditions and at slack tides, and
rotates the cage as needed by hand cranking drive unit 198.
Alternative mooring systems are shown in Figures 24 to
26. These systems are shown with reference to cage 151, but
are equally adaptable to other embofliments of the
submersible cage system. For near shore aquaculture sites
in relatively deep water (e.g. ~0' to 100'), mooring cable
164 runs freely through block 206 (Figure 2~) which is
anchored firmly in the seabed and then to a winch 208 on
shore. The operator can lower cage 151 below the water
surface, or raise cage 151 as the case may be, by winching
cable 164 in or out.
For offshore mooring, cable 16~ runs freely through a
bloc]c 210 (Figures 25,26) which is anchored firmly in the
seabed. Cable 16~ next runs to a two-chambered crown buoy
212; and then is moored firmly to a ballast anchor 21~ in
the seabed. The lower chamber 216 of crown buoy 212 is
filled with foam or other buoyant material. The upper
chamber 218 O;e crown buoy 212 is hollow, open at its lower
exkremity to the water ancl connected at :Lts upper extremity
through a hose 220 to the air above th~ water surface.
Under normal conditions (Figure 25), hose 220 is left open
at its upper end, which allows water to fill upper chamber
218. Lower chamber 216 of crown buoy 212 provides p~rmanent
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floatation sufficient to tension mooring cable 164 and
submerge cage 151 66%.
If it is desired to submerge cage 151 below the
surface, for example in the event of bad weather (Figure
26), air is forced into hose 220 which blows the water out
of upper chamber 218, thereby increasing the buoyancy of
crown buoy 212. The increased buoyancy provides additional
upward force on cable 164 which overcomes the buoyancy of
cage 151. Crown buoy 212 rises and cage 151 submerges below
the surface to a predetermined depth.
As these and other variations and combinations of the
features described above can be utilized without departing
from the spirit of the present invention, the foregoing
description of the preferred embodiments should be taken by
way of illustration rather than by way of limitation o the
present invention as defined in the claims.
