WO2009038471A1

WO2009038471A1 - A method and device for reducing the influence of unwanted organisms in a marine farming facility

Info

Publication number: WO2009038471A1
Application number: PCT/NO2008/000333
Authority: WO
Inventors: Harald Bredahl
Original assignee: Sfd As
Priority date: 2007-09-18
Filing date: 2008-09-17
Publication date: 2009-03-26
Also published as: NO327350B1; NO20074752L; CL2008002754A1

Abstract

A method for preventing unwanted organisms from disturbingly influencing marine farming facilities of the type positioned in the sea, wherein at least one net-pen (1) is used, and wherein the at least one net-pen (1) is provided with at least two electric conductors (4a, 4b, 4c, 4d), wherein the conductors (4a, 4b, 4c, 4d), at least a portion thereof, are connected to the net-pen (1) at a mutual distance, whereby the conductors (4a, 4b, 4c, 4d), when connected to a power-conducting line (2) and subjected to dissimilar polarities, set up an electric field in the water.

Description

A METHOD AND DEVICE FOR REDUCING THE INFLUENCE OF UNWANTED ORGANISMS IN A MARINE FARMING FACILITY

This invention concerns a method for reducing the influence of unwanted organisms in a marine farming facility. More par- ticularly, it concerns a method for preventing unwanted organisms from disturbingly influencing marine farming facilities of the type positioned in the sea, and wherein at least one net-pen is used. The at least one net-pen is provided with at least two electric conductors, wherein the conduc- tors, at least a portion thereof, are connected to the net- pen at a mutual distance, whereby the conductors, when connected to a voltage and subjected to dissimilar polarities, set up an electric field in the water. The invention also comprises a device for practising the method.

A pen-based farming facility is disturbed by many plants and organisms. Sea plants and shells attach themselves to the mesh of the net-pen and result in the pen having to be picked up, washed and impregnated. Animals and birds help themselves to farmed fish, oftentimes having relatively large economic consequences .

It is known that electric fields in the water may assist in keeping plants and organisms away from an area.

Accordingly, Norwegian patent 313931 describes a double net- pen, where each of the two net-pens is made electrically con- ductive, and they are assigned dissimilar polarities. Under normal conditions, net-pens of the type described in NO 313931 are located relatively close to each other, and as such they may be prone to engage each other, particularly during bad weather. A short circuit may thus arise, which may reduce the electric field in the water.

The object of the invention is to remedy or reduce at least one of the disadvantages of the prior art.

The object is achieved in accordance with the invention and by virtue of the features disclosed in the following description and in the subsequent claims.

A method according to the invention for preventing unwanted organisms from disturbingly influencing marine farming facilities of the type positioned in the sea, wherein at least one net-pen is used, is characterized in providing the at least one net-pen with at least two electric conductors, and connecting the conductors, at least a portion thereof, to the net-pen at a mutual distance, whereby the conductors, when connected to a power-conducting line and subjected to dis- similar polarities, set up an electric field in the water.

The electric conductors, which preferably are bare conductors, may also be partially insulated. The conductors may be woven into the mesh material of the net-pen and extend from the surface and down underneath the net-pen, or they may as- sume a zigzag pattern together with an adjacent conductor subjected to the opposite polarity.

Depending on the manner in which the net-pen is produced, there are many possible methods to attach the conductors to the net-pen. For example, the conductors may be tied into the mesh of the net-pen when the conductors are to be attached to a ready-made, manufactured net-pen. It may also be of inter- est to attach the conductors to the net-pen by means of, for example, sleeves, pipes, or rings. The conductors may also be attached to the mesh of the net-pen by means of strips.

For net-pens manufactured from composite materials, it may prove advantageous for the conductors to be glued to the mesh of the net-pen, or for the conductors to be cast into the mesh of the net-pen during manufacturing of the net-pen.

Advantageously, the material of the net-pen is electrically insulating, but it may also be comprised of a material par- tially conductive to electricity. In this connection, a partially conductive material implies a material that conducts electricity poorly, but which may not be referred to as an insulator. In some instances, it may be appropriate for the material of the net-pen to constitute a conductor for one po- larity, whereas the conductors, which in this embodiment are electrically insulated from the net-pen, are subjected to the opposite polarity.

Advantageously, the net-pen may be provided with a bottom ring encircling the lower portion of the net-pen. At least a part of the conductors may be connected to the bottom ring and, if desirable, may support it. Particularly if made from a stiff material, the bottom ring may also contribute to maintain the shape of the net-pen when exposed to relatively strong currents.

In view of the prior art, the method and device according to the invention provide for an appreciable simplification of the components required in order to achieve the intended effect.

In the following, an example of a preferred method and em- bodiment is described and depicted on the accompanying drawing, where: Fig. 1 schematically shows a net-pen provided with conductors according to the invention;

Fig. 2 shows, in larger scale, a section of the net-pen; and

Fig. 3 also shows, in an alternative embodiment, a section of the net-pen.

In the drawings, reference numeral 1 denotes a net-pen connected to an electricity supply (not shown) by means of a line 2.

A number of conductors 4a, 4b, 4c and 4d, see figs. 2 and 3, are connected to the net-pen in various ways.

A distribution line 6 extends from the line 2 and encircles an upper portion of the net-pen 1, insofar as the conductors

4a-4d are alternately coupled to the positive and negative conductors of the distribution line 6.

The conductor 4a is glued to the mesh 8 of the net-pen 1, whereas the conductor 4b is inserted through rings 10 connecting the conductor 4a to the mesh 8.

The conductor 4c is fixedly cast into the mesh 8 during the manufacturing of the net-pen 1. The conductor 4d is attached to the mesh 8 by means of attachment bands 12 made from a metal or a synthetic material .

Claims

C l a i m s

1. A method for preventing unwanted organisms from disturbingly influencing marine farming facilities of the type positioned in the sea, wherein a net-pen (1) is used, c h a r a c t e r i z e d i n providing the net-pen (1) with at least two electric conductors (4a, 4b, 4c, 4d) ; and connecting the conductors (4a, 4b, 4c, 4d) , at least a portion thereof, to the net-pen (1) at a mutual distance, whereby the conductors (4a, 4b, 4c, 4d) , when con- nected to the conductors of a electricity-conducting line (2) , are subjected to dissimilar polarities and set up an electric field in the water.

2. A device for preventing unwanted organisms from disturbingly influencing marine farming facilities of the type positioned in the sea, wherein a net-pen (1) is used, c h a r a c t e r i z e d i n that the net-pen (1) is provided with at least two electric conductors (4a, 4b, 4c, 4d) ; wherein the conductors (4a, 4b, 4c, 4d) , at least a portion thereof, are connected to the net-pen (1) and are positioned at a mutual distance, whereby the conductors (4a, 4b, 4c, 4d) , when subjected to a voltage and assuming dissimilar polarities, are structured so as to be able to set up an electric field in the water.

3. The device according to claim 2, c h a r a c t e r - i z e d i n that the conductors (4a, 4b, 4c, 4d) are woven into the mesh (8) of the net-pen (1) .

4. The device according to claim 2, c h a r a c t e r i z e d i n that the conductors (4a, 4b, 4c, 4d) are tied into the mesh (8) of the net-pen (1) .

5. The device according to claim 2, c h a r a c t e r i z e d i n that the conductors (4a, 4b, 4c, 4d) are inserted through sleeves, pipes, or rings in the net-pen (D •

6. The device according to claim 2, c h a r a c t e r i z e d i n that the conductors (4a, 4b, 4c, 4d) are

5 attached to the mesh (8) of the net-pen (1) by means of attachment bands (12) .

7. The device according to claim 2, c h a r a c t e r i z e d i n that the conductors (4a, 4b, 4c, 4d) are glued to the mesh (8) of the net-pen (1) . o

8. The device according to claim 2, c h a r a c t e r i z e d i n that the conductors (4a, 4b, 4c, 4d) are cast into the mesh (8) of the net-pen (1) .

9. The device according to claim 2, c h a r a c t e r i z e d i n that the material of the net-pen (1) iss partially conductive to electricity.

10. The device according to claim 9, c h a r a c t e r i z e d i n that the material of the net-pen (1) constitutes a conductor for one polarity, whereas the conductors (4a, 4b, 4c, 4d) are subjected to the oppositeo polarity.

11. The device according to claim 1, c h a r a c t e r i z e d i n that the conductors (4a, 4b, 4c, 4d) , at least a part thereof, are connected to a bottom ring.