WO2000049859A1

WO2000049859A1 - Artificial reef

Info

Publication number: WO2000049859A1
Application number: PCT/NO2000/000064
Authority: WO
Inventors: Sverre Meisingset
Original assignee: Norsk Plast-Gjenvinning As
Priority date: 1999-02-26
Filing date: 2000-02-24
Publication date: 2000-08-31
Also published as: NO310901B1; NO990937L; AU2950200A; NO990937D0

Abstract

An artificial reef consists of a cylindrical core (1) having means for receiving substantially radially outward-projecting elements (3) in the form of hollow or solid sections in the form of rods or tubes.

Description

ARTIFICIAL REEF

The present invention relates to artificial reefs. More specifically, the present invention relates to artificial reefs of the type intended to help ensure the development and growth of fry of saltwater fish in their period of maturation.

It is well-known that cannibalism is common among fish, indeed fish even eat their own offspring.

Continuous advances in technology and man^'s ever-increasing exploitation of resources along, beneath and on the seabed are bringing in their wake an ever-greater destruction of the natural reefs on the seabed.

Furthermore, this constantly increasing pollution has also contributed to the laying waste of parts of the seabed, not least beneath and around aquaculture facilities where the seabed is often covered with a thick layer consisting primarily of a mixture of waste from the aquaculture facilities and of non-utilised feed containing feed additives.

In addition, a large part of the world's continental shelf area consists of a sandy bottom which bears a strong resemblance to biological deserts and has a correspondingly very low density of aquatic life.

One of the reasons for this lack of aquatic life may be the absence of permanent surfaces on which micro-organisms can become attached, thereby providing a basis for an aquatic food chain whereby small fish, including fry and naturally small fish, can feed on such micro-organisms without too many of them at the same time becoming themselves food for larger fish.

In recent years efforts have been made to develop so-called artificial reefs in an attempt to contribute to an increase in fish production.

The effect of artificial reefs on fish production has been known for a number of years and an increased fish stock in and around shipwrecks has been observed, and recently serious consideration has been given to the use of redundant drilling rigs as artificial reefs. In addition to providing a permanent bed for aquatic organisms, it has also been proposed that a number of types of artificial reefs be used, for example, for the simultaneous rearing of shellfish, and this is a feature which, even though not initially desired, may nevertheless also be obtained by using such means.

Of the prior art in this field, reference will be made to:

US 3,898,958-A which describes a geometric framework which is easy to assemble, relatively inexpensive and can be extended, so to speak, indefinitely. This framework consists of a linear, three-dimensional network where hollow tubes are pushed into projections projecting at 90° symmetrically in six directions from ball-like connecting elements.

This results in a relatively open and wholly symmetrical structure which looks like climbing frames more than anything else.

FR 2 276 623 describes elements of various shapes, for example, flat panels and hollow, truncated cones stacked on top of one another and having holes in their side faces, and also different geometrical structures and even a plurality of car tyres held above one another by means of various types of ropes, all held in place by a central pole which is anchored in the seabed.

Lastly, US 5,109,796-A describes stacks of superposed pipes with pipes of a relatively large diameter at the bottom, pipes of a slightly smaller diameter having a longitudinal axis at right angles to the subjacent pipes, and a layer of pipes turned 90° (parallel to the first) above that again, where all the layers are bolted together so that the whole structure forms a single unit.

The present invention has developed a simplified type of artificial reef which in quite general terms is characterised in that it consists of a cylindrical core having means for receiving substantially radially outward-projecting elements in the form of hollow or solid sections in the form of rods or tubes.

In a preferred embodiment, the reef according to the invention is characterised in that the core is made in the form of a tube, divided into discs having recesses along their upper and lower edges for receiving the outward-projecting elements in interaction with the recesses in the superjacent and subjacent discs, the interacting recesses forming the receiving means in the form of holes. However, the core might also conceivably be equipped with longitudinal lines and transverse rows of bosses or spikes for receiving hollow sections.

One of the advantages is that the receiving means on the core on the one hand and the outward projecting elements on the other are equipped with mutually interacting fastening or locking means.

Furthermore, it is a major advantage that the inventive reef either can be locked into one unit or is a single unit and that in addition it is equipped with means for optional fastening to lifting tackle for the positioning, removing or moving thereof.

The present invention will be described in more detail with reference to the attached drawings wherein:

Figure 1A shows a core according to the invention, seen from above; Figure IB shows a core disc;

Figure 1C shows a row of superposed core discs, the last two seen from the side; Figure 2 is a sectional top view of a reef according to the invention; and

Figure 3 is a perspective view of a possible embodiment of a reef.

In the illustrated embodiment, the reef core 1 consists of a plurality of superposed ring- shaped elements 4. These elements 4 are provided with evenly distributed semi-circular recesses 5 along their upper and lower edges.

It is preferred that the inventive artificial reef should be tubular and that the ring-shaped elements are rings, but this must not preclude the reef from being solid and the ring- shaped elements from being discs.

When the elements 4 are placed on top of one another to form a complete core 1 which has the shape of a circular cylinder, the lower recesses 5 in a superjacent element 4 form holes 2 with the upper recesses 5 in a subjacent element 4.

In the illustrated embodiment the recesses 5 are semi-circular and the holes 2 are thus circular, but the skilled person will appreciate that the holes can be of any desired cross- section provided that it matches the cross-section of the section which is to be inserted into the hole.

When the elements 4 are thus stacked on top of one another and secured to one another, the sections 3 can be inserted into the holes, and Figure 2 shows a cross-section, seen from above, of a core 1 with inserted sections 3.

As mentioned above, these sections may be in the form of hollow tubes of any desired cross-section or they may be solid, but circular-cylindrical tubes are preferred.

A non-illustrated embodiment is conceivable wherein the core, either whole or in elements 4, is equipped with longitudinal lines and transverse rows of bosses or spikes for receiving hollow sections 3. It is also conceivable that the core may be very thick- walled or even solid and equipped with holes corresponding to the holes 2, intended for receiving sections 3 that are inserted into the holes.

As mentioned above, it is of course an advantage that the reef when assembled should be in the form of a single unit so that it can, with the aid of suitable means, be put in place, removed or moved as required.

The reef according to the invention can be made of any suitable material, but has the great advantage that it can, for example, be made of recycled plastic, both where the core 1 is concerned and where the section 3 is concerned.

The purpose of an artificial reef of this kind is, as mentioned above, to protect fry and small fish in the sea from being eaten by their greatest natural enemy, namely larger fish.

This permits the production of fish in a given area to be increased and also provides the possibility of being able to control the feeding of the fish stock in the area.

The inventive artificial reef has the advantage of progressively smaller spaces between the sections going from the outside towards the centre, and this means that very many different sizes of fish can find their protected grazing areas where they can move relatively freely whilst they grow and then quite naturally must "move outwards in the reef. The reef according to the invention may of course also be a basis for a certain shellfish production, but is primarily intended for use as a grazing area for fish.

Since, as mentioned above, the inventive reef can be made of very cheap materials such as recycled plastics, the invention enables difficult waste to be put to good use and at the same time affords the possibility of creating, improving or increasing aquatic life in a given area.

Claims

P a t e n t c 1 _a i m

1.

An artificial reef, characterised in that it consists of a cylindrical core (1) having means (2) for receiving substantially radially outward-projecting elements (3) in the form of hollow or solid rods or tubes.

2.

The reef of claim 1, characterised in that the core (2) is made in the form of a tube, divided into annular elements (4), having recesses (5) along their upper and lower edges for receiving the elements (3) in interaction with the recesses (5) in the superjacent and subjacent elements (4), the interacting recesses (5) forming receiving means (2) in the form of holes.

3.

The reef of claim 1, characterised in that the core (1) is equipped with longitudinal lines and transverse rows of bosses or spikes for receiving hollow sections (3).

4. A reef according to any one of the preceding claims, characterised in that the receiving means (2) on the core (1) on the one hand and on the elements (3) on the other are equipped with mutually interacting fastening or locking means.

5. A reef according to claim 1 , characterised in that it consists of a solid or thick-walled core having receiving means (2) in the form of bored holes for receiving the elements (3).

6. A reef according to any one of the preceding claims, characterised in that if it is divided into elements (4) it can be locked to form a single unit, and that the reef as a unit is equipped with means for attachment to lifting tackle for the positioning, removing or moving thereof.