Animal husbandry – Aquatic animal culturing – Handling and transportation
Reexamination Certificate
1999-02-11
2001-04-17
Poon, Peter M. (Department: 3644)
Animal husbandry
Aquatic animal culturing
Handling and transportation
C119S203000, C119S208000, C119S223000
Reexamination Certificate
active
06216635
ABSTRACT:
FIELD OF THE INVENTION
The present invention is for an apparatus and method for lifting a net of an aquaculture pen and, to an aquaculture pen incorporating said lifting apparatus and method.
BACKGROUND OF THE INVENTION
Aqulaculture pens are used for the farming of marine animals in natural bodies of water such as scas or rivers. Aquaculture pens typically comprise a floating frame from which a net is suspended, the net defining or forming an enclosure for confining the marine animals to be fanned. The size of the pens can vary considerably but pens having a diameter of 40-50 meters are not uncommon. The pens are anchored in a sea or river so that the marine animals are harvested in an environment similar to that in which they would normally live. Typically the pens are attended to every day for the purposes of feeding and animal husbandry. The current method for harvesting or examining the marine animals held within the pen is archaic, labour intensive and expensive. A typical scenario for harvesting marine animals is for a team of two or three divers to dive into the pen and physically herd the marine animals into each other so that they can be grabbed by hand. Indeed, commonly, when the marine animals are fish, they are physically grabbed by the gills by the divers and then acted upon as necessary.
It is also known to place a pen adjacent the pen holding the animals and for the divers to cut the nets of both pens, stitch them together, and then herd a predetermined number or otherwise selected group of animals into the second pen and then separate and restitch the pens. This may be done to separate animals of different size or other different characteristics.
It will be appreciated that because of the large volume of water bound by the pens the above described method of harvesting and otherwise handling the marine animals is extremely inefficient, labour intensive and expensive.
It is also known that due to the fragile psyche of marine animals, a significant percentage often die through trauma when being harvested in the above mentioned manner. Current estimates are that up to 5% of the marine animals may die due to stress when harvested or handled in this manner.
Hitherto, it had also been thought that the above type of aquaculture pen had little deleterious effect on the environment. It was believed that the natural sea currents and wave motion would clear away the waste products front the pens, which includes the faeces of the animals and uneaten food. However this does not always occur. It is known that storms can cause waste products on the sea bottom to pass through a pen poisoning the captive marine animals. Studies have revealed that the waste products by and large settle beneath the pens on the sea bed have the effect of; killing natural sea grasses; promoting the growth of selected species of marine animals over others to effect the overall ecological balance; and, potentially acting as a poison for the, marine animals held within the pens.
SUMMARY OF THE INVENTION
The present invention was developed to attempt to address and alleviate at least some of the above described problems in the use of current aquaculture pens.
According to a first aspect of the present invention there is provided a lifting system for reducing the volume of an aquaculture pen disposable in a body of water, the pen comprising a frame for suspending a net, the net having a side wall and a bottom submerged wall, the volume of the pen being defined by an inside surface of the net and the surface of the body of water and being at a maximum when the net is freely suspended by the frame, the lifting system including:
a lifting agency for providing a lifting force; and
a coupling member for supporting or connecting to the bottom wall of the net and coupling to the lifting agency;
whereby, in use, the lifting agency can apply lifting force to the coupling member to raise the coupling member together with the bottom wall thereby reducing the volume of the pen from the maximum volume.
Preferably the coupling member is shaped or otherwise configured to lift a central portion of thc bottom wall to form a channel or race in the pen between the frame and the coupling member when the coupling member is lifted.
Preferably the coupling member is disposed below the bottom wall and is constructed to support the central portion in a plane when lifted by the lifting agency.
Preferably the lifting agency is a gas, and the coupling member is selectively inflatable and deflatable with said gas to control the position of the coupling member and thereby vary the volume of the pen.
Preferably the coupling member includes a body having an open bottom and shaped to trap gas for inflation of the member.
Preferably the body comprises an inverted U channel formed in the shape of an annular ring.
Preferably the system further includes guide means supported by the pen and associated with the coupling member to guide the coupling member as it is raised and lowered.
In one embodiment thc guide means comprises a weight supported by the net and configured to allow the coupling member to pass therethrough.
In an alternate embodiment the guide means passes through and slidably engages with the coupling member.
According to another aspect of the present invention there is provided an aquaculture pen including:
a frame for suspending a net, the net having a side wall and a bottom submerged wall which together with the surface of a body of water in which the pen floats defines a confinement region for a plurality of marine animals, pen; and,
lifting system in accordance with the first aspect of the present invention;
whereby, in use, the lifting system can be used to raise the portion of the bottom wall of the net from its lowest submerged position to reduce the volume of the confinement region defined by the net.
Preferably the aquaculture pen further comprises means for collecting waste products from the marine animals held within the pen.
Preferably the collecting means comprises a pan or net of a diameter greater than that of the pen disposed beneath the pen.
Preferably the pen further includes a hollow tubular member which passes through the coupling member and extends to the collection means the tubular member adapted for connection at an upper end to a suction line whereby, waste material gathered on the collection means can be sucked through the tubular member and suction line to a exterior collection vessel.
Preferably said aquaculture pen further comprises means for generating a circular flow of water in the vicinity of the collection means to force waste material within the collection means to gravitate toward the centre thereof and in the vicinity of the tubular member.
According to another aspect of the present invention there is provided a method for selectively reducing the volume of an aquaculture pen of the type disposable in the body of water and comprising a frame and a net suspended by the frame, the net having a side wall and a bottom submerged wall, the volume of the pen being defined by an inside surface of the net and the surface of the body of water, and being at a maximum when the net is freely suspended by the frame, the method comprising the steps of:
providing a lifting agency for providing a lifting force on the net; and
providing a coupling member to support or be connected to the bottom wall and for coupling to the lifting agency whereby, in use, the lifting agency can be operated to apply lifting force to the coupling member to lift the bottom wall of the net thereby reducing the volume of the pen from said maximum volume.
Preferably the method further comprises the step of shaping or configuring the coupling member so that when the lifting agency lifts the coupling member a channel or race is formed within the pen between the frame and the coupling member in which marine animals are confined.
Preferably the step of providing a lifting agency comprises providing a supply of gas, to the coupling member to inflate the coupling member to cause it to rise from a lowest rest position.
REFERENCES:
pate
Abbott Yvonne R.
Poon Peter M.
Sheridan & Ross P.C.
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