GB2033191A

GB2033191A - Breeding Shellfish

Info

Publication number: GB2033191A
Application number: GB7935673A
Authority: GB
Original assignee: SIMONTORPS AKVATISKA AVELSLAB
Current assignee: SIMONTORPS AKVATISKA AVELSLAB
Priority date: 1978-10-18
Filing date: 1979-10-15
Publication date: 1980-05-21
Also published as: SE7810834L; GB2033191B

Abstract

An arrangement for the breeding of shell-fish, in particular crayfish, comprises elements which can be joined together to form continuous wall portions and which are made up of elongated angle sections of plastic material, provided with cup-shaped recesses or spaces 4 intended to constitute protected abodes or hiding- places for the crayfish. <IMAGE>

Description

SPECIFICATION Arrangement in Ponds, Basins and Watercourses for the Breeding of Shell-fish, in Particular Crayfish The present invention relates to an arrangement in ponds, basins and water-courses for the breeding of shell-fish, in particular crayfish, which arrangement is intended to be located below the water surface against the bottom and sides of the said ponds and basins so as to provide haunts and protected abodes for crayfish. The invention also relates to the utilization of the arrangement in connection with the catching of crayfish.

In the breeding of shell-fish, in particular crayfish, there is a relatively large number of animals collected in a limited space and in connection with the recurrent changing of shell the animal is vulnerable to attack from the other crayfish, wherefore protected hiding-places or spaces wherein they can reside and thus escape attack and damage must be provided.

Especially in the breeding of the so-called signalcrayfish (Latin: pacifastacus), which has very strong claws, it has been found necessary to make arrangements for providing the crayfish during breeding with protected places, since otherwise, at least in connection with the shell changing periods, a large number of crayfish will be lost.

It is known that in ponds and basins for the breeding of crayfish protective parts are provided by arranging stones stacked on top of one another, clay pipes or the like, but it has been found that such measures are not always effective in giving adequate protection or a sufficient number of hiding places for crayfish families. By means of the invention, however a simple and cheap arrangement is shown which provides adequate protection for the crayfish and has large capacity, that is to say a great number of hideouts reckoned per surface. Moreover it is possible with the arrangement in accordance with the invention to arrange feeding places near the protective hide-outs of the crayfish, which is not possible if the latter are made up of stones or the like.

An embodiment of the invention will be described in the following with reference to the enclosed schematic drawing, wherein Fig. 1 shows an element in accordance with the invention, and Fig. 2 shows a number of elements joined together to form a lining of part of a basin or pond.

In Fig. 1 is shown an element 1 in accordance with the invention. To save cost, the said element 1 can preferably be made of a relatively thin, weblike plastic material, which is heated to softening, whereupon the softened plastic material is processed by means of deep-drawing, so that cup-shaped spaces 4 are drawn out. Moreover the element is deformed by folding to produce two plane panels 2 and 3 at an angle to each other, the panel 2 being provided with the said cup-shaped spaces 4. If desired the panel 3 may also be provided with an uneven surface structure in that the plastic material, whilst it is still warm and plastically deformable, is processed, e.g. by vacuum forming, so that a channelled or otherwise uneven pattern 6 is engraved in the panel 3.Another way of producing the said uneven surface consists in fixing a granular material, such as sand or grit, by means of an adhesive to the surface of the panel 3.

In the case shown here the panel 3 is provided with an outwardly angled flange 7, which is used for joining together a number of elements in the manner which is described in the following.

The said cup-shaped spaces 4 in the panel 2 of the element are of a length which preferably exceeds the transverse dimension of the openings 5, and the spaces 4 are preferably manufactured with circular cross-section. To stiffen the construction of the element it is possible to arrange between the walls fin-like parts coherent with the said walls which join the cup-shaped parts to one another. These fin-like parts, which may be formed during the deep-drawing operation of the spaces 4, impart great stiffness to the element, which is sometimes desirable. In other cases, however, it may be desirable that the element 1 should be pliable so that it can adapt itself to the curved shapes of the pond walls, and in such cases stiffening connecting parts are not desirable.As is evident from Fig. 1, the openings 5 to the cupshaped spaces 4 are situated in the plane of panel 2 and the openings 5 are arranged close to the panel part 3 projecting outside the openings.

The elements 1 may be produced advantageously of in principle endless strips, which are processed by moulding and cut into suitable lengths. What constitutes a suitable length will be decided in the individual case depending on the structure of the pond. Thus in ponds or basins with straight and long sides, long elements may advantageously be used, whilst in ponds with a more unevenly shaped bottom, shorter elements 1 must be used. If the elements are manufactured from relatively thin plastic material of a thickness of approximately 1 mm, they can easily be cut up to suitable lengths with the help of ordinary scissors.

In Fig. 2 is shown how a number of elements is joined together and is arranged on the bottom of a breeding pond below the water surface of the pond, in that the elements 1 are placed on the bottom and are fixed in that position with the help of long nails or the like which are hammered through the elements. Several elements may be joined together further in that the flange part 7 on the panel 3 of one element is hooked together with the top part of the panel 2 of a second element in the manner as shown, whereafter a number of elements may be built-up stepwise in such a manner that the sides of the pond or basin are lined or covered with the elements in question. To fix the construction it is advantageous to fit self-tapping screws or similar fasteners 9 to the flanges so as to hold together two elements 1 arranged next to one another.The elements in accordance with the invention may also be arranged on a plane basin floor or on the relatively plane floor of a pond, the elements being joined together in the manner as described above, but the spaces 4 will slope upwards a little, as also the panels 3. In other words the elements 1 will be arranged with the point of the V-shaped profile pointing downwards towards the floor of the basin or pond and the panel surfaces 2 and 3 arranged obliquely upwards from the point.

Elements arranged so can also be fixed with the help of long nails or similar devices 8, but they can also be fixed in that bars of a heavier material are placed over the elements and retain them in the joined position. Since in the breeding of crayfish, animals of varying sizes will be encountered, elements with different size of the cup-shaped spaces 4 are required whereby it is possible of course to arrange a larger number of spaces in the elements, if the spaces are smaller.

When the abovementioned elements are joined together in the manner as described and arranged in a pond or basin intended for crayfish breeding, the crayfish will seek spaces 4, of which they take possession in that they enter backwards into the spaces so that they can easily defend the opening 5 of the space without exposing themselves to attack which may be directed towards the soft body, vulnerable after the change of shell. The food, which the crayfish must have, may be laid out on the panels 3 whose uneven structure contributes to the food remaining there and not sliding off, and thanks to the openings 5 of the spaces 4 being placed quite close to the panels 3 where the food is laid out, the crayfish will have their feed within easy reach, which is not always the case in more "natural" environments, where the hide-outs for the crayfish are formed by stone formations etc.Owing to the crayfish having their food within easy reach, the risk of attack during the time they have to leave their protective spaces so as to search for their meal is reduced.

The uneven surface 6, which is achieved through impressions in the material of the panels 3 or through a special coating of granular material, contributes not only to the retention of the food laid out, but also makes it easier for the crayfish to move forwards on the base when they seek out their protective spaces.

it has been found that with elements in accordance with the invention very good safety for the crayfish can be achieved, even in breeding ponds with very high density of animals, and the elements are moreover very cheap, durable and easy to place.

The arrangement in accordance with the invention can also be used advantageously for the catching of the crayfish bred, in that the said elements 1 are lifted out of the water whilst the crayfish are in their spaces 5, but in such cases the elements 1 must of course not be anchored to the bottom, but be provided with weights. The lifting out of the elements 1 may be done advantageously by means of hoisting gear or the like which can be attached to the elements.

It has been assumed in the present case, that the element 1 is manufactured of plastic material, e.g. polystyrene, but it is conceivable also to make the elements of some other material, although the deformation by deep-drawing of the plastic material is probably the cheapest possible method of manufacture. Furthermore it is of course also possible to conceive a variation in the widths of the panels 2 and 3, so as to adapt in this manner the elements 1 to different slopes of the pond walls, that is to say pond walls with small slope would have a considerably wider panel 3. It has been found, however, that the orientation of the elements 1 is not critical in any manner, but that the spaces 4 may slope quite considerably towards the horizontal plane without losing as a result their function as protective hide-outs for crayfish.It is of course more difficult to apply the food onto the panels 3 if these slope excessively, but the coarse structure helps to retain the food so that the location of the panels 3 is also in no way critical.

Instead of anchoring the elements 1 at the bottom of lakes of rivers in the way shown in Fig.

2 by means of nails or similar fixing equipment 8, three or more elements 1 can be interconnected into a triangle, square, rectangle or a similar configuration, whereby the elements are interconnected along their shorter sides in such a way, that they are forming a relatively stiff frame.

This frame can be thrown into a lake or a river without any risk of for that the elements will fall in a wrong direction so that the openings of the cuplike compartments 4 will be pointing downwardly. It is of course also possible to provide a cut in the panel 3 and to bend panel 2 in such a way that the element will form an angle which also will diminish the risk for that the element will be positioned in a wrong way. A still further possibility is of course to bend a very elongated element into a circle by connecting its shorter sides to each other, and to obtain a ringshaped frame construction. The elements can be interconnected in the way mentioned before, i.e.

by means of plugs, screws etc, but also glued together.

Claims

1. An arrangement in ponds, basins or watercourses for the breeding of shell-fish, in particular crayfish, characterizedbyan elongated element comprising at least two coherent panels placed at an angle to one another, one of the panels being provided with a number of cupshaped recesses or spaces arranged side by side, whose mouth portions coincide with the surface of the panel, and that the other panel is arranged in front of and in the vicinity of the said cup-shaped recesses or spaces.

2. An arrangement in accordance with claims 1, characterized in that the said cup-shaped recesses or spaces have a depth which exceeds the largest transverse dimension of the opening.

3. An arrangement in accordance with claim 1, characterized in that the said spaces have a circular cross-sectional area.

4. An arrangement in accordance with claim 1, characterized in that one or both of the longitudinal outer edge zones on the panels making up the said element are provided with folded, flange-like portions, by means of which several elements can be joined to one another.

5. An arrangement in accordance with claim 1, characterized in that the said second panel has an uneven surface structure.

6. An arrangement in accordance with claim 5, characterized in that the said second panel is provided with a surface covering of granular material, e.g. sand or grit which by means of an adhesive is fixed to the panel.

7. An arrangement in accordance with claim 1, characterized in that the said element is manufactured from plastic material.

8. An arrangement in accordance with claim 1, characterized in that a number of elements are adapted so as to be joined together to form a coherent wall portion.

9. An arrangement in accordance with claim 1, characterized in that the individual elements or whole wall portions are fixed to the bottom or sides in the said ponds so as to form a covering wall lining.

10. An arrangement in accordance with claim 1, characterized in that the said elements can be lifted out so as to facilitate the catching of the crayfish present in the spaces 5 of the elements 1.

11. An arrangement in accordance with claim 1, characterized in that one or more of said elements 1 are interconnected along their shorter sides in such a way that a closed frame will be formed.