Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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FIELD OF THE INVENTION
This invention relates to the culture of aquatic ~nim~l~ and more particularly,
to an improved feed con~inment and monitoring device.
BACKGROUND OF THE INVENTION
One of the most difficult and most important tasks in aquaculture is
~el~ ",ining how to feed swimming aquatic ~nim~l~ so as to maximize their growth rate and
the extent of their growth and to minimi7e feed waste. M~ximi7ing growth rates and the
extent of growth is largely a function of the amount of feed which is ingested by the aquatic
animal. It is necesc~ in order to optimize growth conditions, that feed be plcsclllcd and
ingested until satiation is reached. Feeding to satiation, however, is largely subjective. If
three experienced farmers are instructed to feed the same group of fish to satiation under the
same con-lition~, each will deliver a different quantity of feed to the same group of fish. In
some cases this difference has been shown to be as much as 30% between farmers. This
type of discrepancy is inPfficient in aquaculture operations.
Feed monitr.,;l-~ is further complicated by the fact that, as the feed sinks
slowly through the water column, the farmer cannot see the amount of un~ten feed which is
being wasted, as it leaves the enclosed net pen and is therefore beyond the reach of the
penned aquatic ~nim~ls. Depending upon the clarity of the water, water ;U~lclltS, the feeding
behaviour of the aquatic ~nim~l~ and the farmer, enormous q~l~ntities of feed may be wasted.
There are a number of patents for monitoring the amount of sinking feed
which is injected by penned aquatic ~nim~ls- Tntern~tional Application PCT/NO91/00056
published October 17, 1991; United States Patent 4,297,973 issued November 3, 1981 to
Knowles; United States Patent 4,237,520 issued December 9, 1980 to Miller; United States
Patent 4,798,168 issued December 17, 1989 to Vadseth et al; ~n~ n Patent Application
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2,000,443 published April 12, 1990 to Vadset et al; and C~n~ n Patent Application
2,913,496 to Moore-Clark (the "Moore-Clark Patent").
The Moore-Clarke Patent discloses a fairly complex apparatus for retrieval of
unused feed which includes a tapered net connected to a funnel collector, a conduit, a means
for colln~tinp one end of the conduit to an outlet of the collector, an air diffuser and a
dewatering box.
Each of the devices described in the foregoing patents, including the
Moore-Clark Patent, is de-~ign~d to remove particulate matter, inclu(ling unused feed, from
the aql-~culture cage or pen. Recently, however, there has been a trend in mamlf~cturing
and market ~lem~nd from sink;n,~ feeds to feeds which float in both fresh and salt water. In
principle, flo~ting feeds provide an excellent way of monilor;ng the consumption by the
aquatic ~nim~l~ since a direct observation of the feed rem~ining on the water surface will
give a quick and precise de~e~ ination of the feed ingestion. In practice, however, much of
the feed is removed from the aquaculture cage, pen or raceway by wind action, water
wllc;nts and the feeding behaviour of aquatic ~nim~ls. This constant removal makes
monilor;ng of feed a completely futile exercise under many c~nditions. Currently, there is
no way to deal efflciently with this wasteage.
It an object of the present invention to obviate or mitig~te the above
disadvantages.
SUMMARY OF TIIE INVENTION
The present invention provides a feed monitoring and cont~inment device
which compri~es a collar having an open top and bottom, a vertical skirt eYten-ling from the
collar such that when the device is in use, the skirt is undel~v~ler and together with the
collar, acts as a barrier to the passage of floating feed from within the confines of the device,
said device being adapted to be placed in an environment of aquatic animal culture to enable
monito~;ng of feed co~sumption and cont~inm~nt of feed.
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The feed monitoring and cont~inmPnt device of the present invention, when
di~rose~ within an aqU~çl~ltllre cont~inmPnt such as a cage, pen or raceway, retains the feed
placed within the enclosure in such a manner that it is unaffected by wind and current actions
or the feeding behaviour of the aquatic anim~ls. Once the fln~ting feed is place in the
confines of the device, a farmer can readily assess the nature and rate of feed consumption.
The ability to monitor consumption in an easy and accurate manner not only m~ximi7es the
growth of the aquatic ~nim~ls within the culture environment but greatly decreases the feed
wasted and the res~llt~nt pollution in the water from over-feeding.
A further object of the present invention provides a method of m~mlf~ctllring a
feed molliLol;n~ and cont~inm~nt device which comprises folding a sheet of suitable
water-proof polymer in half to form a closed edge and an open edge, sealing a line across the
folded sheet at a distance closer to the open than the closed edge, sealing the open edge to
form an elongate dual-chambered tube with two ends, and sealing the end of the tube
together to form a complete enclosure.
This method is simple and relatively inexpensive and produces a device which
may be readily stored and transported. It is to be understood, however, that this method of
m~nufactllre may not be a~rop~iate for all embo~lim~nt~ of the device as contemplated
within the scope of the present invention. The collar and skirt may be made of many types
of m~teri~l~ as described further hereinbelow. Where, however, the m~t~ri~l selected for the
collar and skirt are polymer-based, and where it is desired that the two components be
integral, the method described herein may be app,opliate. Further details of the method are
provided hereinbelow.
DESCRIPIION OF THE DRAWINGS
The present invention is described by way of the following non-limiting
drawings in which:
Figure 1 is a perspective view of an infl~ted feed moni~oring and con~inm~nt
device ~ ted within an aquaculture pen;
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Figure 2 is a perspective view of a d~fl~ted feed monitoring and cont~inm~nt
device;
Figure 3 is a cross section through line 3-3 of Figure l; and
Figure 4 is a perspective view of another embodiment of the device attached
to a sea cage.
l~REFFRRF.n EMBODIMENTS OF THE INVENTION
In a prer~lled form of the present invention the feed monitoring and
con~ ".~nt device compri~es, very simply, a collar which is open ended at the top and
bottom and which may or may not be buoyant, and a skirt eYtPn(ling from the collar, where
in both the collar and skirt are non-porous to feed m?,tçri~l.
Referring to Figure 1, a feed monitoring and cont~inment device is in~ ted
gener~lly at 10 within sea-cage 12. The device comprises a collar 14 and a skirt 16 integral
with and eYten~ing from the collar. A plurality of cut-outs 18 are inteI~el~ed along the
distal edge of skirt 16. As best seen in Figure 3, a stabilizing means 20 may be disposed
within the skirt through one of cut-outs 18. This stabilizing means may be any weight such
as lead line or chain weight which is suitable to m~int~in the skirt in a vertical position when
in use despite wave action, wlle~ and animal movement. Depending upon the m~ttori~l
used to make skirt 16, a stabilizing means may not be necç~ . For example, if the skirt is
made of a fairly rigid m~tçri~l such as resin, polymer-i.l.~fegn~ted foam or fabric, or
hardened plastic (l~min~ted or single layer plastic) such as belting m~t~ri~l used for conveyor
belts and the like, then a stabilizing means may not be neceS~ry.
Collar 14 is depicted in all of the Figures as an inflatable tube, although as
cus~ further hereinbelow, buoyancy is not essçnti~l for the collar if either:
(1) a buoyant holder to which the device may be removably or perm~nçntly
~thclled is provided; or
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(2) a means is available for removable or perm~nPnt ~tt~chment of the device to a
part of the aqll~(cultllre cont~inmçnt
Additionally, buoyancy within the collar may be achieved by numerous means.
The collar itself may be inflatable as depicted in the Figures. The collar may not be
inflatable but may be made of a suitably buoyant m~tPri~l as described further hereinbelow.
Collar 14 is provided in Figure 3 with a sealable air portal 22 through which
the collar may be infl~ted prior to use.
The collar and skirt may be made of a wide variety of m~teri~ls depending on
the structure and size of aquaculture cont~inment and the water and wind conditions within
that envi-u~ ent. Generally, any m~tPri~l which is marine grade and which does not permit
the passage of flo~ting feed pellets may be used. For eY~mple, wooden, cork or rubber
floats may be used for the collar and a suitable mesh or net may be used for the skirt. The
collar may ~ltern~tively be made of any closed-cell foam including, but nût limited to
eYp~nded poly~lylene foams or polyurethane foams. The main consideration with respect to
the choice of foam is that it should not take on water. The skirt may ~ltprn~tively be made
of a subst~nti~lly rigid m~teri~l such as those described hereinabove.
Although in a preferred embodiment the collar is buoyant, it is not essçnti~lly
so. The collar may be removably or pprm~nently attached to a holder within the aq~ ultme
con~ ent This holder may be as simple as a buoyant support or it may be an ~tt~ hmPnt
means such as rope, braided cûrd, wires or the like tû connect the device tû some part, such
as a wall or side, of the aquaculture cont~inm~nt.
Generally, an aquaculture cage or pen comprises a vertical net wall
approxim~tPly 1 meter above the water line and a further vertical net wall of about 17 meters
under the surface which is connected or integral with the horizont~l net floor. It is
cont.s-~"pl~ted that the device of the present invention may be secured to one or more of the
vertical walls by any applûpliate attachment means such as rope, braided cord, wire and the
like. If the device is buûyant, the ~tt~chmçnt means need not be as supportive of the device
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in the water and may be designed accordingly. Conversely, if the device is not buoyant, the
~tt~r-hm~nt means will need to be more secure, incorporating perhaps, two walls of the sea
cage.
With reference to Figure 4, a feed monitoring and cont~inm~nt device is
in-lir~ted generally at 26 comrrising a collar 28 and a skirt 30. Skirt 30 is ~tt~h~d to wall
32 of sea cage 34 by braided cord 36.
In a plcf~llcd form of the present invention the collar and the skirt are integral and
are formed of a polymer-based m~tçri~l. This m~t~ri~l may be selected from any waterproof
elas~ul"~l~, plastics or any other suitable polymers. Non-limiting examples include natural
rubber, synthetic rubber (formed by copolymeri7~tion of but~diene and styrene), polyvinyls
such as polyvinylc~-loride and polyvinylacetate, polyurethans, polyisobutylene,
polychloro~fene and poly~yrene. It is to be understood, however, that these m~tPri~ls ma
be used even if the collar and skirt are not integral.
In another prcfelled embodiment of the invention, the device may be formed,
in whole or in part, of a combination of a core m~tPri~l and a covering m~teri~l, whereby the
core m~teri~l is naturally buoyant such as a foam (described hereinabove) and the m~tPri~l
covering the foam is polymer-based (also described hereinabove) to provide a smooth outer
surface on which the feed will not stick or become lodged. The core may also comprise a
scrim fabric or cloth such as polyester. Most preferably, the core is a polyester fabric and
the covering m~t~ri~l is a polyvinyl or polyurethane.
It is to be understood that the device of the present invention may be of any
size or shape which is practical and suitable for a given aquaculture cont~inmPnt Although
the Figures depict a circular device, it may ~lt~rn~tively be, for example, square,
rectangular, triangular or oval.
Simil~rly, the ~lim~nsic)ns of the device of the present invention may be
tailored to each particular aquaculture environment. For example, in areas of si~nific~nt
current activity, it may be desirable to increase the length of the skirt and in areas of high
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wave action to increase the diameter or cross section of the collar which protrudes above the
water line. In a ple~elled form of the present invention the diameter or cross section of the
collar is approxim~tP-ly one-third and the skirt length the rem~ining two-thirds of the total
length of the device. The diameter of the collar is preferably between 7 cm and 30 cm and
is most preferably between 10 cm and 15 cm. In a prefelled form, the length of the skirt
may range between S cm and 60 cm and most preferably between 20 cm and 40 cm.
The diameter or width of the entire device may also very greatly depending on
the environment in which it will be used. Generally it will be between 2 meters and 10
meters and more speçific~lly between S meters and 7 meters.
In operation, a farmer places feed 24 for aquaculture cont~inmP-nt within the
confinPs of collar 14 and skirt 16. Any food which is un~tPn is retained within the device
until such time as it is consumed by the aquatic ~nim~l~ When all of the food is consumed,
its absence is immeAi~tPly observable by the farmer by ex~mining the surface of the water
within the confines of the device. The farmer is then able to monitor the times between
f~ing~ and the rate of consumption of food to avoid wastage and to ensure satiation of the
aquatic ~nim~ls. More feed may then be added as required. Accordingly, food management
and efficiency of the aquaculture farm greatly increases with the use of the device of the
present invention.
It is to be understood that this device may be used in many types of
aqu~ulhlre farms for all swimming aquatic ~nim~l~ and more particularly for finfish and
crust~ ns
Referring Figure 2, collar 14 and skirt 16 are depicted in the storage, transport
or non-use position. In this embodiment of the invention, air may be removed from
collar 14 through air portal 22 and stabilizing means 20 may be removed through cut-outs 18
so that the entire device may be flattened for ease in storage and transport. The device, so
fl~ttenP,d, may be rolled up or suitably folded to decrease its size.
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In one embodiment of the present invention as described above, the device
may be formed of a polymer-based m~teri~l Such an embodiment may be made readily be
the following steps:
1) folding a sheet of a suitable waterproof polymer in half to form a closed
edge and an open edge;
2) sealing a line across the folded sheet at a distance closer to the open edge
than the closed edge;
3) sealing the open edge to form an elongate dual-chambered tube with two
ends; and
4) sealing the ends of the tube together to form a complete enclosure with two
ch~mbers.
The device, so formed, has one chamber which is capable of being infl~te~, thereby forming
a collar, and another chamber forming the skirt. The skirt may optionally comprise a
stabilizing means as described above.
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