GB2350539A

GB2350539A - Shellfish cultivation system

Info

Publication number: GB2350539A
Application number: GB9908398A
Authority: GB
Inventors: David Porteous Flockhart
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-04-14
Filing date: 1999-04-14
Publication date: 2000-12-06
Anticipated expiration: 2019-04-14
Also published as: GB9908398D0; GB2350539B

Abstract

A shellfish cultivation system 1 suitable for use in cultivating oysters and the like. The system 1 comprises a support structure 2 for supporting above the ground a plurality of enclosed shellfish cultivation bags 4 stacked one on top of the another. Each of the bags 4 is provided with at least one bag support member 14 formed and arranged for maintaining the top and bottom surfaces of a bag 4 in a spaced apart orientation with respect to each other when bags 4 are stacked one on top of another and for supporting a bag 4 stacked thereon. Each bag support member 14 engages a bag 4 at at least two points on the top surface thereof and at at least two points on the bottom surface allowing water and food to flow freely through said stack of bags 4. There may be rods 8 on the support structure 2 passing through openings 13 in bags 4 to secure them. Stacks of bags 4 may be suspended by rods (32 figure 5) passing through openings 13.

Description

2350539 CULTIVATION SYSTEM The present invention relates to a system and

apparatus for cultivating crustacea, particularly a system for cultivating molluscs and bivalves such as scallops and oysters.

Currently, crustacea such as scallops and oysters are cultivated by a number of methods using a variety of apparatus.

oysters are generally cultivated in large rectangular shaped bags formed from a netting material. The bags (loaded with growing oysters) are generally placed and secured:lonto bag support structures (located in the inter tidal zone of the beach or f oreshore), wherein the bag support structures consist of two or more horizontal support bars running generally parallel to each other which bars are supported by legs embedded securely into the seabed.

The bags are of a generally flattened tubular design and are formed from a polymeric plastic material. The mesh size of the netting material is chosen such that the growing oysters will not fall through the mesh during the normal routine operations of oyster cultivation which includes rotating the bags every few weeks to ensure even growth of the oysters in the bags. Suitable netting materials will be known to those skilled in the art such as those disclosed in FR 2521065 which -2teaches of a plastic netting with trapezoidal mesh holes and suitable for cultivating shell fish.

Typically only one layer of bags is placed on the bag support structure as the net-like material from which the bags is constructed is not rigid enough to support the additional weight of one or more bags placed on the top of it especially when the shell fish contained therein have matured and are therefore quite large. Stacking in this way is undesirable as it is necessary to maintain at least a minimum water flow through the bags to ensure the viability and growth of the oysters contained therein.

There are commercially available spacers which are placed inside the net bags to keep the bags surfaces spaced apart without unduly restricting the flow of water through the bags but these are difficult to use and not sufficiently strong to allow one or more bags to be placed on top of each other. The spacers are generally in the form of a rod provided with pushclip attachment means at each end thereof. The rods are placed inside a bag and the push-clip attachment means are attached to the mesh of the bag in such a f ashion so as to push the bag apart thereby maintaining a relatively open internal volume within the bag. Such rods are manufactured and marketed by INTERMAS S.A. of Spain.

-3Rod-like spacers of this type are both difficult and awkward to position and locate properly within bags. They are also prone to disengagement at one or both ends during the routine handling procedures of oyster cultivation. Furthermore, the spacers do not provide adequate structural support for the stacking of one or more bags on top of one another. Bags with the rod-like spacers tend to collapse laterally when a lateral force is applied such as the pulling off of a top bag (from a table with two or more layers of bags) to rotate and reposition the bag. This is especially the case when the oysters within the bag have reached a reasonably large size such that their combined weight causes the bag to flex when being moved or handled.

Any loss in the structural integrity of the bags resulting in crushing of the bags can lead to a significant decrease in water flow through the bags and is undesirable in that it generally leads to a decrease in the rate of growth of the oysters, as well as a general loss of condition, and even mortality, if the water flow is too low for prolonged periods of time.

To overcome this problem of stacking of bags with reduced water flow therethrough, FR 2590765 (INTERMAS S.A.) provides for a number of rigid, flattened, rectangular cages (instead of net bags) which are formed from a plastic material. The cages are formed and arranged to fit within a simple framework -4or suspended from a cable or chain to form a stack of cages. The rigid cages and framework disclosed in FR 2590765 are not interchangeable with the bags which are currently widely used in the commercial cultivation of crustacea/shellfish and have 5 proved to expensive to use and maintain.

Further problems in cultivating crustacea lie in the tables upon which the bags are placed. Generally the bags are secured to the table by use of long longitudinal rod running the full length of the table which is secured in place over the bags to prevent them being dislodged from the table by the tide.

This system is not adequate to prevent the bags from being dislodged as a result of tidal movement or during routine handling operations when the longitudinal rod is removed to allow access to the bags. When bags are moved about on the tables it is quite common that bags are dislodged and slip through the horizontal support bars, or off the back of the table and onto the surrounding ground which may be sandy and which can contaminate the oysters leading to gritty oysters which are commercially less valuable.

It is an object of the present invention to avoid or minimise one or more of the abovementioned advantages.

-5The present invention relates to a shellfish cultivation system suitable for use in cultivating oysters and the like which system comprises a support structure formed and arranged for supporting above the ground a plurality of enclosed shellfish cultivation bags stacked one on top of the another in use of the system, each of said bags being provided with at least one bag support member formed and arranged for maintaining the top and bottom surfaces of a said bag in use of the system in a spaced apart orientation with respect to each other when said bags are stacked one on top of another and for supporting a said bag stacked thereon and shellfish contained therein in use of the system, each said bag support member engaging a said bag at least two points on said top surface thereof and at least two points on said bottom surface whereby a plurality of bags can be stacked one on top another with the shellfish contained therein spaced apart from the shellfish contained in other adjacently stacked bags and to allow water and food to flow freely through said stack of bags.

Thus with a shellfish cultivation system according to the present invention, oyster bags and the like may be stacked one on top of another without collapsing under the weight of other bags and thereby allowing a greater number of bags to be placed on a given area of f oreshore.

Preferably there are provided two, desirably three, bag support members spaced apart along a bag for supporting the top and bottom surfaces of a said bag in a substantially spaced apart orientation. 5 Said bag support members may be formed and arranged so as to be external of the bag, though preferably said bag support members are formed and arranged to be placed inside a bag.

Any suitable means of securing the support members may be used, for example cable ties or the like, though preferably the support member has a more or less rectangular shape and the corners of the member interengage with holes in the bag, which has a net-like structure, so as to locate securely the support in a bag.

Preferably said support structure is in the form of a trellis of generally similar type and construction to that used in the cultivation of oysters and the like. Desirably said support structure is provided with a plurality of vertically extending pin members arranged in a medial portion of said support structure and formed and arranged to pass through apertures in said bag on said support structure and to prevent lateral movement of said bag with respect to said support structure.

Preferably each of said vertical extending pin member engages and passes through an aperture in said bag support member. This is desirable as it prevents any lateral forces, such as -7the effect of the tide, acting directly in the bag instead transferring such forces into said bag support structure.

Preferably said vertically extending pin member has an upward extent of at least twice the depth of a bag supported by a bag support member, desirably three to five times. Thus said pin member may have an upward extent of from 200 mm to 500 mm or more.

Alternatively and for use with "lanternff type growing arrangements said support structure is in the form of an elongate vertically extending beam or cable/rope(s) having a base portion for supporting the base bag of a plurality of bags stacked thereon, wherein said vertically extending beam or cable/rope(s) passes through a said bag and a said bag support member. This arrangement allows for five or more bags to be supported by said beam from an offshore rig or pontoon or on poles and is particularly suitable for use in growing scallops.

Further preferred features and advantages of the present invention will now be further described by way of example of some preferred embodiment illustrated with particular reference to the following specific examples and drawings in which: Fig. 1 shows a perspective view of a shell fish cultivation system according to the present invention; -8Fig. 2 shows a side view of the shell fish cultivation system according to the present invention; Fig. 3a shows a bag with three internal supports according to another aspect of the present invention; Fig. 3b is an enlarged section of Fig. 3a, showing the interengagement of the internal support means with the mesh of a bag; Fig. 4 is a representation of a lifting pole for use with the present invention; and Fig. 5 is a representation of a second embodiment of the shellfish cultivation system according to the present invention.

A shellfish cultivation system, generally indicated by reference number 1, is shown in Fig. 1. The system 1 comprises a bag support structure 2, and several bags (only one bag 4 shown) supported on the bag support structure 2. The bag support structure 2 is fabricated from steel rods cut and welded together using conventional methods.

The bag support structure 2 is rectangular in outline when viewed from above and is provided with three pairs of substantially upright legs 5 in the form of an inverted letter,U' located at one at each opposing end and one in the middle of the bag support structure 2. The legs 5 are embedded into the foreshore substrate (not shown) to prevent the bag support -9structure 2 from moving under the action of waves and/or tides.

The three pairs of legs 5 support and are conjoined by three parallel horizontal support bars 6 which curve upwardly at each end to form end stops 7. The middle bar of the three horizontal support bars 6 has a plurality (six shown) of vertically extending securing rods 8 fixed thereto.

The end stops 7 are located at a distance of approximately half the width of a bag 4 from the closest vertically extending securing rod 8, see Fig. 2.

The end stops 7 and the vertically extending securing rods 8 locate the bags and prevent the bags from moving laterally or radially under wave or tidal action and this secures the bags 4 onto the bag support structure 2. By placing the bags onto the vertically extending securing rods 8 such that they pass through the mesh 12 (see Fig. 1) of the bags 4 and openings 13 of the middle internal support structure 14, the bags 4 are prevented from any unwanted slippage, rotation or other movement on the bag support structure 2.

With reference now to Fig. 2 the bags 4 are stacked vertically in two layers on the support structure 2 such that the internal support structures 14 within the bags 4 of the second layer are positioned directly above the corresponding internal -10support structures 14 of the f irst layer which are resting upon the horizontal support bars 6 directly thereunder. In this way the internal support structures 14 provide continuous load bearing support to the bags 4 of the f irst and second 5 layers.

The bags 4 (see Fig 3a) are constructed from a polymeric material in a flattened tube form. Bags of this type are manufactured by companies such as INTERMAS S.A. of Spain and/or NORTENE of France.

Within each bag 4 are three internal support structures 14 according to another aspect of the present invention. (Only two shown in Fig. 3a. for clarity - a third internal support structure is shown in broken line).

The internal support 14 (see Fig. 3a) is rectangular in outline and is provided with two parallel major side portions 16 and two parallel minor side portions 18. Each of the major and minor side portions 16 and 18 respectively is rectangular in section (not shown).

The internal support 14 is further provided with two support structures 20 which are located close together near the mid points of the opposing major side portion 16 such that the support structures are parallel to the minor side portions 18. The support structures 20 provide additional structural rigidity to the internal support 14 and in the central support are for locating the bag on the vertically extending rods 8 on the bag support structure as shown in Fig. 1.

At each of the corners the major and minor side portions 16 and 18 meet there are provided ball shaped lugs 22, which extend generally outwardly from the internal support 14. The lugs 22 interengage with the apertures 24 in the mesh of the bags 4 (see Fig. 3b) in a ball and sockettype arrangement.

The internal support 14 is positioned in the bag 4 and the ball-shaped lugs 22 are pushed through the apertures 24 of the mesh of the bag 4, thus securing the internal support 14 within the bag 4.

The central portion of the support structure 14 define a space or passageway 26 (Fig. 3a) which is in direct communication with circular openings 13 in each of the major side portions 16. The openings 13 allow a lifting pole 30 (see Fig.3) to be inserted therethrough. The lifting pole 30 comprises a rod section 32, an attachment loop 34 located at the top of the rod section 32 and a rectangular base section 36 located at the lower end of the rod section 32. In use the lifting pole 30 passes through the openings 13 of the internal support 14 (when in place within a bag 4) such that the attachment loop 34 protrudes from the top of the bag 4.

-12There are three rectangular internal supports 14 placed within the bags 4 thus providing adequate support to the bags 4 and a corresponding number (three) of lifting poles 30 are also used. The rod section 32 is long enough to allow three bags 4 to be placed on the lifting pole 30 and leave the attachment loop 34 protruding from the top.

The attachment loop 34 is attached to a cables 38 via hooks 40. The cables 38 are afixed to a bar 42 located above the water surface (A) such that the lifting poles 30 and the bags 4 secured thereon are suspended below the surface (A) of the water (see Fig. 5). The bags 4 are shown as being separated by optional plastic spacers 44 placed onto the lif ting poles 30.

The foregoing description is intended to illustrative of some of the preferred aspects of the present invention. It is intended that the scope of the present invention extends to the variations and embodiments which will be apparent to those skilled in the art. Various modifications may be made to the embodiments described above without departing from the scope of the present invention.

Claims

CLAIMS 1 A shellfish cultivation system suitable for use in cultivating

oysters and the like which system comprises a support structure formed and arranged for supporting above the ground a plurality of enclosed shellfish cultivation bags stacked one on top of the another in use of the system, each of said bags being provided with at least one bag support member formed and arranged for maintaining the top and bottom surfaces of a said bag in use of the system in a spaced apart orientation with respect to each other when said bags are stacked one on top of another and for supporting a said bag stacked thereon and shellfish contained therein in use of the system, each said bag support member engaging a said bag at least two points on said top surface thereof and at least two points on said bottom surface whereby a plurality of bags can be stacked one on top another with the shellfish contained therein spaced apart from the shellfish contained in other adjacently stacked bags and to allow water and food to flow freely through said stack of bags.
2. A shellfish cultivation system according to claim 1 wherein there are provided two or three bag support members spaced apart along a bag for supporting the top and bottom surfaces of a said bag in a substantially spaced apart orientation.
-143. A shellfish cultivation system according to claim 1 or claim 2 wherein said bag support member is formed and arranged so as to be external of the bag.
4. A shellfish cultivation system according to claim 1 or claim 2 wherein said bag support member is formed and arranged to be placed inside a said bag.
5. A shellfish cultivation system according to any one of claims 1 to 4, wherein there is provided means for securing the support member to a said bag.
6. A shellfish cultivation system according to anyone of claims 1 to 5 wherein the support member has a more or less rectangular shape and the corners of the member inter-engage with holes in the bag, which has a net-like structure, so as to locate securely the support in a bag.
7. A shellfish cultivation system as claimed in any one of claims 1 to 6 wherein said support structure is in the form of a trellis.
8. A shellfish cultivation system as claimed in any one of claims 1 to 7 wherein said support structure is provided with a plurality of vertically extending pin members arranged in a medial portion of said support structure and formed and arranged to pass through apertures in said bag on said support -15structure and to prevent lateral movement of said bag with respect to said support structure.
9. A shellfish cultivation system as claimed in claim 8 wherein each of said vertical extending pin members engages and passes through an aperture in said bag support member.
10. A shellfish cultivation system as claimed in claim 8 or claim 9 wherein said vertically extending pin member has an upward extent of at least twice the depth of a said bag supported by a bag support member.
11. A shellfish cultivation system as claimed in claim 8 or claim 9 wherein said vertically extending pin member has as upward extent of from three to five times the depth of a bag supported by a said bag support member.
12. A shellfish cultivation system as claimed in any one of claims 8 to 11 wherein said pin member has an upward extent of from 200 mm to 500 mm.
13. A shellfish cultivation system as claimed in any one of claims 1 to 6 wherein said support structure in the form of an elongate vertically extending beam or cable/rope(s) having a base portion for supporting the base bag of a plurality of bags stacked thereon, wherein said vertically extending beam -16or cable/rope(s) passes through a said bag and a said bag support member.
14. A shellfish cultivation system as claimed in claim 13 wherein a central portion of the bag support member defines a space or passageway which is in direct communication with circular openings in each major side portions of a said bag.
15. A shellfish cultivation substantially as described hereinbefore and with reference to Figs. 1, 2, 3a and 3b of the accompanying drawings.
16. A shellfish cultivation system substantially as described hereinbefore and with reference to Figs. 4 and 5 of the accompanying drawings.