NZ734267B - Subsurface shellfish farm - Google Patents

Abstract

open seas or adverse weather conditions shellfish farms are subjected to undesired wave action. If ropes supporting mussels, directly or indirectly, are suspended below the waterline then in such conditions they can be subjected to increased stress. It is an object of a preferred form of the invention to address this problem. Accordingly in a preferred embodiment of the invention there is a shellfish farm comprising a plurality of floats 3 at or near water level, backbone threads 2, elastic threads 3 extending between the floats and the backbone thread and shellfish threads 5 extending from the backbone thread with shellfish attached. vention to address this problem. Accordingly in a preferred embodiment of the invention there is a shellfish farm comprising a plurality of floats 3 at or near water level, backbone threads 2, elastic threads 3 extending between the floats and the backbone thread and shellfish threads 5 extending from the backbone thread with shellfish attached.

Description

COMPLETE SPECIFICATION TITLE Subsurface Shellfish Farm FIELD OF INVENTION This invention relates to the field of shellfish farming and in particular to subsurface mussel farming.

BACKGROUND Mussels have been farmed in the Marlborough Sounds in New Zealand for some years. A typical mussel farm includes a number of floats connected by two backbone ropes. Each backbone rope runs along one side of a line of floats and is connected to each float.

Mussel growing ropes are hung from the backbone ropes and extend below the waterline.

In open seas or adverse weather conditions mussels near the surface are subjected to wave action. If the backbone ropes are suspended below the waterline then in such conditions they can be subjected to increased stress. Stress on the floats leads to stress on the backbone ropes and also the shellfish growing ropes.

It is an object of a preferred embodiment of the invention to go at least some way towards addressing the above. However, it should be appreciated that the invention has more general application, and so any objects or advantages applicable to a preferred embodiment should not be seen as a limitation on the scope of the claims expressed broadly. The object of the invention per se is simply to provide the public with a useful choice.

The term “comprising”, if and when used in this document, should be interpreted non- exclusively. For example, if used in relation to a combination of features it should not be taken as precluding the option of there being further unnamed features.

SUMMARY OF THE INVENTION A shellfish farm comprising:  a plurality of floats at or near water level;  a backbone thread;  shock absorbing threads extending between the floats and the backbone thread;  at least one shellfish thread extending from the backbone thread with shellfish attached.

Optionally there are at least two backbone threads similarly arranged.

Optionally at least two shock absorbing threads extend between each float and the backbone threads.

Optionally each shock absorbing thread is elastic.

Optionally each shock absorbing thread connects to a respective float by way of a collet secured around the shock absorbing thread and a collar secured around the collet, wherein the collar is nested in an aperture extending through the float.

Optionally each shock absorbing thread is connected to a/the backbone thread by way of a hook.

Optionally each shock absorbing thread is connected to a hook by way of a collet secured around the shock absorbing thread and a collar extending around said collet, wherein the combination of these is secured in a recess of the hook.

IMAGES Some preferred embodiments of the invention will be further described with reference to the accompanying images in which: Figure 1 illustrates a marine subsurface mussel farm; Figure 2 is a cross-sectional view showing detail through a float within the farm; Figure 3 is a cross-sectional view a mode of connecting the float to a shock absorbing thread; Figure 4 is a side view of a hook forming part of the farm; and Figures 5A-D are isometric views of an alternative hook and the manner it is connected to a shock absorbing thread; and Figure 6 is an isometric view of various parts of the farm.

DETAILED DESCRIPTION Referring to figure 1, a marine subsurface mussel farm has a number of floats 1 at or near the waterline, each connected to a pair of submerged backbone ropes 2 via elastic (eg cords 3 and hooks 4. The cords 3 may be substantially formed from rubber, for example as a single strand or from multiple strands. A number of submerged mussel growing ropes 5 are suspended from the backbone ropes 2 and trail deeper down into the water.

The growing ropes 5 have growing or mature mussels attached.

The length of the elastic cords 3 is such that, in calm conditions, the growing ropes 5 start at a predetermined distance below the waterline. In preferred embodiments, the only connection between the floats 1 and the growing ropes 5 comes via the elastic cords 3 and the backbone ropes 2. In alternative embodiments, the floats 1 may be connected together by a suitable line. One or more anchors (not shown) may be used to anchor the farm to the seabed.

Each float 1 is substantially in the form of a capsule having a cylindrical centre with hemispherical parts either side. The floats 1 may be hollow or filled with foam or some other suitable material for buoyancy. In further embodiments the floats 1 may be any other suitable shape.

Referring to figure 2, each end 6 of each float 1 is profiled to enable easy connection of a respective one of the elastic cords 3. More specifically, at each end a first vertical aperture 7 runs top to bottom and has a broader central opening 8. The opening allows a shock absorbing cord to be correctly housed within the aperture. The aperture 7 also has a shoulder 9 immediately below the central opening 8.

Figure 3 shows the float’s profiled end 6 when connected to one of the cords 3.

Because the cord is elastic it can be stretched, and when this occurs it constricts or has at least a region of lessor diameter. As shown, the cord 3 has been stretched in this way to fit a collet 10 of a lessor diameter than the region of cord it engages. As also shown, a collar 11 has been fitted around the collet 10 to assist with a secure connection to the cord 3. More specifically, the collar 11 sits snugly in the recess 9. Because the collar 11 is wider than the parts of the aperture 7 below the recess it resists downward pulling on the cord 3 so that the cord is securely held. To help keep the collet 10 engaged with the collar 11 and for more accurate placement, a lower laterally protruding rim of the collar extends inwardly into a narrowed part of the collet, as illustrated at 12.

As will be evident from figure 3, the outer diameter of the collet 10 is less than that of most of the aperture 7 (ie the parts above and below the central opening 8 and the recess 9).

This enables the cord 3 with the collet 10 attached to slide through the aperture 7 when being fitted. The collar 11 is fitted to the collet 10 when these parts are in the larger central opening 8 (ie there is plenty of room there to enable this). When that has occurred the collar/collet/cord combination is lowered until the collar 11 sits in the recess 9 in the manner described above. The cord 3 will therefore remain connected to the float 1 until the collar 11 is removed by reversing the process.

In alternative embodiments the cord 3 may simply be knotted at both ends of the aperture 7 to prevent it from pulling free of the float 1. However the mode of attachment described above is preferred.

Each elastic cord 3 prevents or at least reduces shock forces on the floats 1 from being transmitted to the backbone ropes 2 and from there down to the shellfish growing ropes 5 and shellfish. This means that in rough seas where the floats 1 may be experiencing a lot of movement, significantly less movement is transmitted to the shellfish. More specifically, when the floats 1 are moving in rough seas the cords 3 stretch and absorb force transmitted by the floats 1 so that the backbone ropes 2 (and shellfish ropes 5) are less subject to movement than would otherwise be the case. The cords 3 therefore serve as shock absorbers.

The backbone ropes 2 are preferably made of polypropylene, but any suitable alternative material may be used. In some less preferred embodiments the backbone ropes may be substituted by alternative forms of thread, for example a rod.

Referring to figures 1 and 4, each hook 4 is used to connect a shock absorbing cord 3 to a backbone rope 2. The hook 4 has an aperture 13, tab-like guides 14 and a front groove 15. In each case an elastic cord 3 is threaded through the aperture 13 and held by friction between a pair of the guides 14. The hook 4 is then hooked around a backbone rope 2 and the end of the cord 3 pushed into and frictionally held in the groove 15. In this manner the cord 3 loops around the backbone rope 2. Preferably the groove 15 is in the shape of an open channel where the opening is wide enough to admit the cord 3 (eg when constricted by stretching) and narrow enough to retain the cord (eg by friction) when the stretching force is relaxed.

Figures 5A-D showsan alternative hook4a when in use with the shock absorbing cord 3 for fastening to a backbone rope 2. As shown the cord 3 is inserted into an aperture 16 in the top of the hook. A collet 10a and collar 11a are used to retain the cord 3 in the aperture 16 in a similar way to that described for the float 1. Therefore the cord 3 is secured against forces that would otherwise tend to pull it out of the hook 4a. The aperture 16 may include a shoulder-like fastening recess for the collar 11a (eg similar to the recess 9 above, for similar engagement).

The hook’s collet 10a may be applied to the cord 3 before or after the cord is inserted into the hook’s aperture 16. More particularly, after the cord 3 has been inserted into the aperture 15, the collar 11a is attached to the collet 10a and the cord 3 then pulled back up through the top of the hook to move the collet 10a and collar 11a into position.

Referring further to figures 5A-D, the hook 4a has two lower apertures 17, 18 in its curve.

After the cord 3 has been passed through the aperture 16 at the top of the hook and the collet 10a and collar 11a are in place, the cord is passed through the aperture 17 and then back through the aperture 18. A backbone rope 2 is then inserted into the hook 4a as shown at figure 4C.

The hook 4a includes a lower groove 19 into which the backbone rope 2 is nested. The groove 19 is an optional way of keeping the backbone rope 2 in the desired position with respect to the elastic cord 3.

When the backbone rope 2 has been positioned in the hook the elastic cord 3 is pressed into front groove 20 in a tight friction fit. In alternative embodiments, the front groove 20 may be substituted by an aperture and another collet and collar combination in the manner described above.

Referring to figure 6, an elastic cord 3 is shown when 3 attached to a hook 4a at one end and to a collet 21 and collar 22 at the other end. A backbone rope 2 is shown passing through the hook 4a.

While the invention has been described with relation to mussel farming it has broader application. I may for example be used with appropriate other forms of shellfish.

While some preferred aspects of the invention have been described by way of example it should be appreciated that modifications and improvements can occur without departing from the scope of the following claims.

Claims (7)

1. A shellfish farm comprising:  a plurality of floats at or near water level;  a backbone thread; 5  shock absorbing threads extending between the floats and the backbone thread; and  at least one shellfish thread extending from the backbone thread with shellfish attached. 10

2. A shellfish farm according to claim 1, wherein there are at least two backbone threads similarly arranged.

3. A shellfish farm according to claim 2, wherein at least two shock absorbing threads extend between each float and the backbone threads.

4. A shellfish farm according to any one of claims 1 to 3, wherein each shock absorbing thread is elastic.

5. A shellfish farm according to any one of claims 1 to 4, wherein each shock 20 absorbing thread connects to a respective float by way of a collet secured around the shock absorbing thread and a collar secured around the collet, wherein the collar is nested in an aperture extending through the float.

6. A shellfish farm according to any one of claims 1 to 5, wherein each shock 25 absorbing thread is connected to a/the backbone thread by way of a hook.

7. A shellfish farm according to claim 6, wherein each shock absorbing thread is connected to a hook by way of a collet secured around the shock absorbing thread and a collar extending around said collet, wherein the combination of these is 30 secured in a recess of the hook.