WO2020048915A1

WO2020048915A1 - Hatching box

Info

Publication number: WO2020048915A1
Application number: PCT/EP2019/073332
Authority: WO
Inventors: Sveinung Alvestad
Original assignee: Sval Aqua As
Priority date: 2018-09-03
Filing date: 2019-09-02
Publication date: 2020-03-12
Also published as: NO344204B1

Abstract

It is described a hatching box (1) and a method for production of fish fry. The hatching box (1) comprises a bottom plate and four wall plates wherein at least one of said wall plates have a perforated area (3), and that the bottom plate is a substrate plate with perforations (4) and a plurality of vertical pins (5), wherein said bottom plate and wall plates are moulded in one piece.

Description

HATCHING BOX

Technical Field

The present invention relates generally to a hatching box, in particular a hatching box with an artificial substrate for salmonid farming. Background

In fish farming, eggs are artificially fertilized and developed in hatcheries. An artificial substrate can be placed in the hatching tray for better yield. The eggs are typically placed on a grate or similar above the substrate and stay there during the egg state. When entering the yolk-sac larval state, the larvae will move through the grate onto the artificial substrate. It is then important to have a place to hide away while consuming the yolk-sac, or else the fish larvae will be forced to swim too early. Swimming too early will have undesired consequences such as loss of weight and increased mortality.

Cleanliness is very important for the health of the fragile creatures living in a hatching tray. If the trays, trough or substrate plates are not thoroughly cleaned, the danger of infection will significantly increase. The number of components to be cleaned, and disassembled, effects the amount of labour involved in each cleaning process. With increased labour, the system is more vulnerable.

The eggs, larvae and fry are all very small in size and can therefore easily escape through tiny cracks or gaps. It is therefore crucial that the boxes containing them are tightly assembled. Materials can shrink or contract and fastening means can wear over time, causing joints to be torn apart. Damages can also occur during handling. It is therefore a never-ending risk of escape.

N019824003/N0151 266 concerns a double hatching plate for use in hatcheries for fish farming, especially salmonids. By placing a double hatching mat with opposing pins in the base of common undercurrent devices it creates a resting place for the larvae.

W02006130020 / N020052617 refers to a substrate plate for use in hatchery systems consisting of through holes or perforations and vertical support pins or spikes with a predetermined height. These pins provide support for a grating or mesh plate for hatching. The substrate plate is also equipped with spreading pins that are lower than the support pins. The perforation provides for the replacement of water, but the holes are too small to allow fry to pass. Both the spreading pins and the support pins have the function of spreading the fry and limit the swimming activity. The fry will move down through the upper mesh plate and settle down between the pins. These substrate plates are inserts fitted in the hatching trough or assembled to wall plates.

A further publication is the article“System where the fish eggs lie on the bottom - Aquaculture” by Odd Ivar Lekang. The hatching trays described in this article can be placed in rows in a trough and have perforations in the bottom and in one of the side walls (also known as the California system). Water is supplied at one end of the trough and will flow through the perforated bottom of a first tray, through the layers of fish eggs which are located on the tray, and through the side perforation into the next zone of the hatching trough, before entering a second tray the same way as the first, and so on. Artificial substrate plates can be placed at the bottom of these trays for better results.

DE 43 16 995 is concerned with a cage aimed at facilitating the natural reproduction of fish in a fishing water. The mesh-sided cages are positioned where the fish roe and the spawn collectors comprise shaped strips set vertically over the cages. The fish rub over the strips and the spawn is collected to drop into the cages. The cage floors are covered with marine plants and the entry side of the water flow through the cages has absorbing panels to generate a warm water flow through the cages.

Summary of the Invention

The present invention has the objective of providing an improved hatching box, in particular with regard to the issues of escape and cleanliness.

Said objectives are fully or partially achieved by a hatching box according to the independent claims. Preferred embodiments are set forth in the dependent claims.

According to a first aspect, the invention relates to a hatching box for production of fish fry, comprising a bottom plate and four wall plates wherein at least one of said wall plates has perforations and the bottom plate is a substrate plate with perforations and a plurality of vertical pins, wherein said bottom plate and wall plates are moulded in one piece.

By moulding the perforated substrate plate, the hatching box and all the vertical pins as one piece, the cleaning procedure is made faster due to fewer items to clean and no required disassembly and reassembly. All areas of the hatching box are easily accessible, ensuring thorough cleaning is made easy. With thorough cleaning comes better hygiene. Thus, the risk of infection between productions are strongly reduced or even eliminated. This combined design cause fewer manufacturing processes and reduced material consumption; hence, the production is simplified, and the production costs reduced. Compared to assembled hatching boxes the present invention eliminates the risk of gaps occurring, through which larvae or fry can escape.

Some of the vertical pins can have V-shaped or X-shaped cross-sections (x-pins). The vertical pins with V-shaped or X-shaped cross-section will provide stabilization of activity and movement of the larvae and fry in a better way than those with a circular cross-section. Each x-pin provides four separate spaces each sheltered from two sides, where v-pins also provide shelter and separated areas. This feature provides the larvae/fry with a sheltered area where to grow without using energy on unnecessary movement/swimming.

Some of the vertical pins can be adapted to support a roe box, preferably at a height below the perforated area of the side wall.

The perforations in at least one side wall of the hatching box forms a water outlet. By having a distance from the top off the wall to the perforations in the same wall, the water level will not rise to a level where eggs, larvae or fry can be washed over the edge.

The cleaning process is further facilitated by avoiding sharp inner edges and / or corners in the hatching box.

As a further means to fight infection, the hatching box material can comprise an antimicrobial polymer or a polymeric biocide. According to a second aspect, the invention relates to a method for production of fish fry in hatching boxes where the hatching boxes have a bottom and four side walls, wherein at least one of said walls have a perforated area, and the bottom is a substrate plate with perforations and a plurality of vertical pins, and the entire hatching box with said components is moulded in one piece, which method comprises at least the steps of: placing a roe box with fertilized fish eggs on at least some of the vertical pins, supplying water through the perforations in the bottom at a rate allowing all the water to escape through the perforated area in the at least one side wall, removing fry from the hatching box, and emptying and cleaning the hatching box.

The described method will provide a simplified and predictable production of fish fry which facilitates cleanliness in the hatching box and eliminates the risk of escape.

In summary, all the above identified advantages will positively affect the economy of the end user.

Brief Description of Figures

The invention will now be described with reference to the exemplifying

embodiments shown in the accompanying drawings, wherein:

Fig. 1 shows a top view of the hatching box,

Fig. 2 shows a side view of the hatching box, and

Fig. 3 shows a perspective of the hatching box.

It should be noted that the features in the drawings are not drawn on the same scale.

Reference numerals

1. Hatching box 2. Vertical pins with X-shaped cross-sections

3. Perforations/perforated area of wall

4. Perforations/perforated area of bottom/substrate plate

5. Vertical pins

Detailed Description

Fig. 1 shows an embodiment of the hatching box 1 from a top view. The hatching box 1 is box-shaped with an open top and a square bottom; however, other shapes can be used e.g. hexagonal, any polygonal or circular/oval shape. A continuous wall, comprising four wall plates, extends from the square periphery of the bottom of the hatching box 1. The top edge of said wall is provided with an outwards collar.

The bottom of the hatching box 1 is a substrate plate (a surface on which organisms live). Said substrate plate is perforated 4 and has vertical pins 5. Perforations 4 in the substrate plate must be big enough to provide a sufficient flow of water, as they serve as a water inlet, but at the same time be small enough to prevent the organisms living on it from passing through. Depending on the required volumetric flow rate, the perforated area 4 of the bottom can be adjusted by

increasing/decreasing the hole count. The entire substrate plate should be perforated in order to provide a flow of new water to all areas of the hatching box 1. Fry and larvae situated in the hatching box 1 will preferably be evenly distributed over the area of the substrate plate. For the wellbeing of all the fry and larvae in the hatching box 1, it is therefore important to avoid dead spots with stagnant water. Ideally, the distance from the base of a vertical pin 5 to its surrounding perforation 4 holes should be as short as possible.

The vertical pins 5 extend upwardly from the bottom of the hatching box 1. These vertical pins 5 are evenly distributed over the entire area of the bottom of the hatching box 1. One purpose of the vertical pins 5 is to spread the fry and larvae. Vertical pins 5 used to spread the fry and larvae typically have circular cross- sections. A second purpose of the vertical pins 5 is to stabilize and prevent activity and movement among the fry and larvae. Vertical pins 5 used to stabilize and prevent activity and movement among the fry and larvae have V-shaped or X- shaped cross-sections 2 (x-pins). Isolated spaces are created by the V-shaped or X- shaped cross-section. Each space is formed in the area between two perpendicular side plates. In an alternative embodiment the angle between side plates can be an obtuse angle or an acute angel, preferably between l20°and 90°. The areas between the bottom plate and adjoining side plates are areas where a flow of new water arrives in the hatching box and they are thus very important. Thus, the areas between adjoining side plates must be sufficiently perforated 4. The vertical pins with V-shaped or X-shaped cross-section 2 are of the same height, taller than the other vertical pins 5. By being of the same height, the vertical pins with V-shaped or X-shaped cross-section 2 are adapted to support a roe box. The vertical pins 5 with a circular cross-section in the figures doesn’t necessarily have to be circular and can be of various heights.

Fig. 2 shows the hatching box 1 from a side view. At least one of the wall plates is provided with a perforated area 3. Perforations 3 in the wall must be big enough to provide a sufficient flow of water, as they serve as a water outlet, but at the same time be small enough to prevent the organisms living in the hatching box 1 from passing through. This perforated area 3 is located in an upper part of the wall plate. To avoid organisms being washed over or escape over the edge of the wall, the perforated area 3 can preferably be located at a distance below said edge.

Depending on the required volumetric flow rate, the perforated area 3 can be adjusted by increasing/decreasing the hole count or resizing the area itself, heightwise or lengthwise. In Fig. 2 the perforated area 3 ranges the entire length of the wall plate and has a height corresponding to approximately one third of the box height; however, this may be adjusted according to the volumetric flow rate. In an alternative embodiment, a plurality of wall plates can have perforated areas 3. The vertical distance from the bottom of the hatching box 1 up to the perforated area 3 of the wall plate will set the water depth in the hatching box 1. All wall plates may have a draft angle to ease the release of the hatching box from the mould.

Fig. 3 shows a perspective of the hatching box 1. The hatching box 1 is moulded in one piece. The hatching box 1 moulded in one piece comprises four connecting walls, wherein at least one wall has a perforated area 3, and a bottom plate, in form of a substrate plate with perforations 4 and vertical pins 5. Additive manufacturing is an alternative to moulding of the hatching box 1. Suitable materials are food approved and may be selected from the group of polymers or metals. Preferred polymers are selected from the group consisting of polypropylene, polyethylene and acrylonitrile butadiene styrene, (ABS). To reduce the risk of infections the hatching box can be made of an antimicrobial polymer, or an antimicrobial polymer may be mixed with a polymer such as polypropylene or polyethylene.

To ease the cleaning process, inner edges and corners should be rounded.

Water is supplied through the perforated area 4 of the bottom of the hatching box 1. In this sense the perforated area 4 of the bottom of the hatching box 1 forms a water inlet. As the water level rises, it will at some point reach the perforated area 3 of the at least one wall plate. Water will leave the hatching box 1 through the perforated area 3 of the wall plate. In this sense the perforated area 3 of the wall plate forms a water outlet. The required volumetric flow rate and the perforations 3, 4 must be aligned, such that the water level doesn’t exceed the perforated area 3 of the wall. If the water starts to flow over the edge of the wall, so can the roe, larvae and fry. The vertical pins with V-shaped or X-shaped cross-section 2 adapted to support a roe box should position the roe box level at a height in which the roe is sufficiently covered by water. When hatched, the larvae move down below the roe box into the space defined between the roe box, the wall plates and the bottom plate of the hatching box 1. The space defined between the roe box, the wall plates and the bottom plate of the hatching box 1 form a substrate box. Larvae will come to rest in the substrate box where they consume the yolk-sac and grow into fry. The vertical pins 5, and in particular the vertical pins with V-shaped or X-shaped cross-section 2, will spread the larvae and provide shelter. After a completed production of fry, the fry is transferred and the hatching box 1 is emptied. Thorough cleaning of the hatching box 1 is then performed before the next production of fry is initiated.

Claims

1. A hatching box (1) for production of fish fry, comprising a bottom plate and four wall plates wherein at least one of said wall plates has a perforated area (3), characterised in that the bottom plate is a substrate plate with perforations (4) and a plurality of vertical pins (5), wherein said bottom plate and wall plates are moulded in one piece.

2. A hatching box (1) according to claim 1, wherein the perforated area (3) of at least one of the wall plates is located in an upper part at a distance from the upper edge of said wall plate.

3. A hatching box (1) according to any preceding claims, wherein the plurality of vertical pins (5) have various heights and cross-sections.

4. A hatching box (1) according to any preceding claims, wherein at least some of the vertical pins (5) have V-shaped or X-shaped cross-sections (2).

5. A hatching box (1) according to any preceding claims, wherein at least some of the vertical pins (2) are of the same height and taller than the other vertical pins (5), in order to support a roe box.

6. A hatching box (1) according to claim 5, wherein the roe box is supported at a height below the perforated area (3) of the at least one side wall.

7. A hatching box (1) according to any of the preceding claims, wherein the hatching box (1) is made of a food approved polymer selected from the group consisting of polypropylene, polyethylene and acrylonitrile butadiene styrene.

8. A hatching box (1) according to any of the preceding claims, wherein the hatching box (1) comprises an antimicrobial polymer.

9. A hatching box (1) according to claim 1, wherein all inner edges and corners are rounded.

10. A method for production of fish fry in hatching boxes (1) characterised in that the hatching boxes (1) have a bottom and four side walls, wherein at least one of said walls have a perforated area (3), and the bottom is a substrate plate with perforations and a plurality of vertical pins (2), and the entire hatching box (1) with said components is moulded in one piece,

which method comprises at least the steps of:

placing a roe box with fertilized fish eggs on at least some of the vertical pins,

supplying water through the perforations in the bottom at a rate allowing all the water to escape through the perforated area in the at least one side wall,

removing fry from the hatching box (1), and

emptying and cleaning the hatching box (1).