WO2024100021A1

WO2024100021A1 - A fish singulation system and method

Info

Publication number: WO2024100021A1
Application number: PCT/EP2023/080954
Authority: WO
Inventors: Kristján FINNUR SÆMUNDSSON; Ásgeir SÆVARSSON; Unnsteinn GRÉTARSSON; Magnús INDRIÐASON
Original assignee: Marel Iceland Ehf.
Priority date: 2022-11-08
Filing date: 2023-11-07
Publication date: 2024-05-16

Abstract

A system and a method for transferring an irregular stream of arbitrarily oriented fish into a single-file stream of fish. Fish is delivered from a first conveyor to a second conveyer which comprises a plurality of dividing structures. To form the single-file stream, the system comprises a singulation sensor configured to identify slots containing more than one fish, and to reject fish from such identified slots.

Description

A FISH SINGULATION SYSTEM AND METHOD

INTRODUCTION

The invention relates to a fish singulation system configured to transfer an irregular stream of arbitrarily oriented fish into a single-file stream of fish. Each fish in the stream of fish defines a longitudinal direction from a head region to a tail region, and the system comprises a first conveyor extending between a first inlet and a first outlet, and a second conveyor extending between a second inlet and a second outlet. Since the second inlet is arranged to receive fish from the first outlet, the system defines a downstream conveying path from the first inlet to the second outlet.

BACKGROUND

In fish handling, specific processes, e.g., de-heading, gutting, or filleting, often require a specific orientation and timing of the fish. However, fish is typically transported in bulk. There is hence a need for processing bulk fish into a single file of periodically timed well-oriented fish.

Typically, bulk fish are introduced onto a conveyor resulting in an irregular stream of fish where fish are randomly orientated, not periodically timed, and possibly lying on top of each other. In some facilities operators are manually handling the irregular stream of fish onto a subsequent conveyor in order to achieve a single-file of periodically timed well-oriented fish. As labor is getting more scarce and therefore possibly more expensive, there is a need to automate at least parts of this process.

Machines for transferring an irregular stream of food objects, such as fish, into a single-file of food objects, that are possible periodically timed and/or oriented, exist.

To describe these operations, the following definitions are used in this document,

- singulation means the process of forming a single-line of non-overlapping fish (not necessarily orientated or periodic),

- periodic singulation refers to the process of forming a singulated line of with substantially equal distances between the fish (not necessarily oriented), and - orientation refers to the orientation of the fish along the head-tail direction and/or the belly-back direction. Orientation can be partial, i.e. head-tail or belly-back, or full, i.e. head-tail and belly-back.

It is understood that substantially equal distances refer to distances that are similar so that the stream of fish can be handled efficiently by industrial machinery. The distances are not exactly equal as this is not needed and because the fish are never exactly the same size.

It hence follows that a single-line stream of periodically timed food items that are aligned in the longitudinal and in the transverse directions is denoted as a periodically singulated and fully oriented stream of food items.

As with all industrial processes, there is a continuous desire to improve throughput. However, in industrial handling of fragile food objects, such as fish, high speed processing may not always work optimally as the products are prone to sustain damage.

Often, the value of the fish will be reduced by rough handling leaving marks or otherwise damaging the fish.

Whereas small and/or inexpensive fish are typically handled with focus on speed rather than caution, the balance between speed and caution becomes particularly relevant when handling expensive species such as fish of the Salmonidae family including salmon or similar relatively expensive fish species such as catfish etc., or even larger fish such as tuna or halibut etc.

There is hence a need for an improved, stable, and reliable high throughput processing system to singulate and possibly orient food objects such as fish.

SUMMARY

To improve speed in handling fragile fish, and to protect the fish better, embodiments of the disclosure, in a first aspect, provide for a fish singulation system configured to convert an irregular stream of arbitrarily oriented fish into a single-file stream of fish of the kind mentioned in the introduction wherein the system comprises a first and a second conveyor and wherein the second conveyor defines a row of adjacent slots.

Additionally, the system comprises a rejection structure arranged to reject at least one fish from a slot identified to contain more than one fish. Since the system comprises a rejection structure, fish can be rejected while the fish is protected in the slots of the second conveyor, and the system allows for carrying out singulation in two separate process steps: a step where the fish is received by the second conveyor, and a step where fish are rejected from selected slots if said slots contain more than one fish, preferably such that said selected slots contain at most a single fish after removal of the redundant fish.

As mentioned, the first singulation step separates fish from each other at the interface between the first and the second conveyor, i.e. when the fish is delivered from the first conveyor into the slots of the second conveyor. As a result, each slot typically, however, not always, contains only a single fish.

In the subsequent, second step, selected fish, and only selected fish in slots identified as containing more than one fish are rejected such that all slots contain at most a single fish. It is understood that the word 'rejected' indicates the removal of fish from slots containing more than a single fish. Rejection hence does not indicate a defect in the quality of the fish but instead a correction of the stream of fish to achieve a singulated file.

Due to the separation of the first step from the second step, the first step of separation of fish from each other can take place at high speed, and potentially, the second step of rejecting fish is only to be considered for relatively small sub-group of the fish, namely only for those slots having more than one fish.

This process can therefore potentially be carried out at a much lower speed and therefore more gently. Accordingly, only the first step of separating the fish needs great care relative to the balance between speed and caution, and this need can be accomplished by the slotted structure of the second conveyor which can gently separate the fish even at high processing speed. Particularly, it has been found that the fish is protected well when received in individual slots, and that the risk of damage is reduced in the later step of rejecting selected fish.

In operation, bulk fish may be received by the system via a hopper or chute forming a funnel or initial storage until the fish slides from the first inlet towards the first outlet. In this stage, the fish is conveyed in an irregular stream of arbitrarily oriented fish. The fish may even partly overlay each other.

When the fish reaches the interface between the first outlet and the second inlet, they are, preferably, received one-by-one in slots by the conveyor belt. This converts the irregular stream into a single-file stream. Should one slot receive more than one fish, the singulation sensor identifies such slots, and the rejection structure removes at least the excessive fish and potentially all fish in that slot.

The first conveyor could be a belt conveyor or a sliding conveyor, e.g., with rollers, or simply with a low friction and inclined surface, e.g., of stainless steel or plastic on which the fish can slide. It may e.g., form an elongated path from the first inlet to the first outlet, or it may form a curved path. The first conveyor may also comprise different sections using different conveying principles, e.g., belt conveyor sections and sliding sections.

The second conveyor may define a conveyor belt, particularly an endless belt rotating between two drive pulleys. The conveyor belt may define an upper surface movable in a second conveying direction and a plurality of dividing structures extending upwards from the upper surface to an upper edge, the upper edge extending in a longitudinal direction transverse to the second conveying direction to divide the conveyor belt surface into the slots.

The dividing structures may extend upwards from the upper surface and define an upper edge. The dividing structures could be separate components adhesively bonded and/or bolted to the conveyor belt, or the belt could be made in one piece with dividing structures.

The upper edge of the dividing structures extends by definition herein, in a direction referred to as a "longitudinal direction". This direction could be transverse or potentially perpendicular to the second conveying direction in which the fish is conveyed by the second conveyor.

The dividing structures divide the conveyor belt surface into a row of adjacent slots. The purpose of these slots is preferably to house only a single fish when conveyed from the second inlet to the second outlet.

The system may comprise a singulation sensor configured to identify the slots containing more than one fish. The rejection structure could particularly comprise a re-circulation conveyor which returns the fish to the first conveyor, e.g., to the first inlet, based on a signal from the singulation sensor.

In an alternative embodiment, the rejection structure could comprise a rejection arm extending transverse to the second conveying direction across the upper surface and arranged to interact with fish not being completely contained in the slot. This may be achieved by shaping and sizing the slots relative to the type of fish intended for the system such that presence of more than one slot inevitably prevents the excessive fish to be fully contained in the slot. In this case, an arm located close to the upper edge may swipe that fish, which is not fully contained in the slot, out of the slot.

Another alternative implementation of the rejection structure may comprise a robot configured to remove selected fish from a slot containing more than one fish.

The singulation sensor may e.g., comprise a camera and a connected vision detection computer system programmed to identify a fish in a picture. If more than one fish is detected, the singulation sensor defines a corresponding electronic singulation signal for the rejection structure, and the rejection structure may comprise power operated means reacting on the electronic singulation signal to direct the fish back to the first conveyor when there is more than one fish in a slot.

The system may comprise a re-orientation structure, e.g., located downstream the interface between the first and second conveyors and configured to reorient selected fish. This may provide uniformly oriented fish by orienting all fish with the head region and tail region pointing in the same directions. It is hereby understood that the term downstream is used in the usual fashion to indicate a later processing event. Similarly, the term upstream is used to denote previous processing events.

The re-orientation structure may comprise a re-orientation sensor configured to identify an orientation of the fish, e.g., by identifying a tail region distinct from a head region of a fish. The re-orientation sensor may be arranged to identify the orientation when the fish is in the slots of the second conveyor.

The re-orientation sensor defines an electric orientation signal representing an orientation of the fish in the slot. In a simple implementation, the orientation signal may simply be a digital signal of 1 or 0 depending on the head being to the left or to the right. The skilled person would consider alternative solutions.

The re-orientation sensor may be constituted by the singulation sensor. The combined singulation and re-orientation sensor may e.g., be in the form of a camera with suitable image recognition software to identify the number of fish in a slot and the orientation of the fish. In one implementation, the output from such a combined singulation and re-orientation sensor could be 0, 1, or 2 where 0 indicates more than one fish in a slot, 1 indicates only one fish and head to the right, and 2 indicates only one fish and head to the left.

The system could comprise a routing structure configured to route the fish from the second outlet to a selected one of at least three conveyors based on a signal from the reject structure or a signal from the re-orientation structure. The system may comprise a recirculation conveyor, a re-orientation conveyor, and a delivery conveyor.

In the example where the combined singulation and re-orientation sensor provides an output in the form of 0, 1, or 2, the corresponding action of the routing structure could be to route the fish to the re-circulation conveyor in case of 0, to the re-orientation conveyor in case of 1, and to the delivery conveyor in case of 2.

The routing structure may e.g. comprise a pivoting lid movable between three positions allowing the fish to be received by one of the three conveyors.

The re-circulation conveyor may direct the fish back to the first conveyor, and it may e.g. form a chute towards the first conveyor. A chute, in this context, is a low friction surface on which the fish can slide.

For this to work exclusively by sliding the fish on the chute by gravity, the second conveyor may extend in an upwards direction from the interface such that a major part of the second conveyor is higher than the first conveyor relative to gravity, and the chute or basin may be under that part of the second conveyor which is higher than the first conveyor.

By this structure, fish delivered at the second outlet on the re-circulation conveyor may simply slide towards the first conveyor and thereby be returned into the conveying path. In an alternative implementation, the re-circulation conveyor comprises a power-driven conveyor belt. In that case, the level of the first conveyor relative to the second conveyor matters little, since the re-circulation structure may move fish wherever it is dropped from the second conveyor in an upwards direction to a position where it is delivered to the first conveyor.

The re-orientation conveyor may form a loop such that all fish are turned from an orientation where the head is e.g., turned right to an orientation where the head is turned left.

Subsequently, the re-orientation conveyor could arrange the fish in a buffer or directly on a takeaway conveyor.

Depending on the orientation signal, the re-orientation conveyor may receive fish from the second outlet.

If the fish is already oriented in the intended orientation, it can be moved directly to a buffer or to the takeaway conveyor by the takeaway conveyor. In one embodiment, the system comprises a first buffer for fish being re-oriented, and another, second, buffer for fish already being in the intended orientation on the second conveyor and therefore not being re-oriented.

The optional buffer(s) may contain slots for individual storage of a plurality of singulated fish, and it may allow a more continuous operation of the system.

Due to the above-described structure, the system may define three routes after the second outlet, being towards the first conveyor by use of the re-circulation conveyor, towards a reorientation conveyor, or directly towards a buffer or takeaway conveyor by the delivery conveyor.

The first outlet may define a longitudinal delivery edge terminating the first conveyor and extending along the longitudinal side of an adjacent one of the dividing structures such that the fish is delivered into one of the slots in direction being transverse to the longitudinal direction and being transverse to the first conveying direction. During operation and moving of the conveyor belt of the second conveyor, the upper edges of the dividing structures may all pass the delivery edge in an orientation where they are parallel with the delivery edge.

The distance between the upper edge and the delivery edge may particularly be smaller than an expected size of the fish such that the fish is unlikely to enter in a gap between the upper edge and the delivery edge. With this in in mind, the distance from the upper surface to the upper edge may exceed the distance from the upper edge of the adjacent one of the dividing structures to the delivery edge and the first conveyor may define a transverse conveyor section being non-perpendicular to the delivery edge.

The first conveyor may define a perpendicular conveyor section being perpendicular to the delivery edge. This perpendicular conveyor section may particularly terminate the first conveyor, i.e. it may extend up to the delivery edge such that the fish is moved in a direction perpendicular to the delivery edge to the point where they are delivered into the slots. This may provide a more precise delivery of fish into the slots.

At least one, and particularly a plurality of deflectors may be arranged across the conveying path for deflecting fish while they are moved on the first conveyor. This may provide a preorientation of the fish before they reach the interface and therefore ensure a more precise delivery of the fish into the slots. Each deflector may e.g., extend from a first end, e.g., located at an edge of the first conveyor, to a free end located between the edges of the first conveyor. When a fish bumps into such a deflector, its position will change, and depending on the angle of the deflector relative to the conveying path, the fish may typically be oriented longitudinally relative to the deflector, e.g., such that the ventral or dorsal side of the fish slides along the deflector.

The deflectors may be straight, elongated, beams extending from one side of the first conveyor towards, an opposite side of the first conveyor - however, not reaching the opposite side of the first conveyor and thus allowing the fish to slip passed the deflector at that opposite side.

The deflectors may particularly have an oblique angle relative to the conveying path meaning that the free end points downstream in the conveying direction. An oblique angle could be anything from below 90 degrees to the conveying direction to e.g., 10 degrees to the conveying direction.

The system may e.g., comprise 2 or 3 deflectors fixed as stationary pins or walls extending at different angles relative to the conveying path and offset relative to each other along the conveying path. When the fish bounces between the deflectors, it further improves the preorientation and thus the ability of the slots to receive the fish.

In this respect, different angles of the deflectors relative to the conveying path may further improve the system, particularly, one deflector may extend at an angle selected e.g., between 80 degrees and 70 degrees with a free end of the deflector pointing downstream, and another deflector may extend at an angle between 70 and 60 degrees with the free end pointing downstream.

In a second aspect, the disclosure provides a method of transferring an irregular stream of arbitrarily oriented fish into a single-file stream of fish, each fish defining a longitudinal direction from a head region to a tail region, by use of a system according to any of the preceding claims, the method comprising delivering fish into an adjacent one of the slots in direction being transverse to the longitudinal direction and being transverse to the conveying direction, and returning the fish to the first conveyor in case it is rejected from the second conveyor.

The fish could be delivered into the slot in an arbitrary orientation, and all fish having the tail region oriented in the same direction could be rejected from the second conveyor prior to rejection of fish not having the tail region oriented in that direction. BRIEF DESCRIPTION OF THE DRAWING

The accompanying drawings are included to provide a further understanding of embodiments and are incorporated into and forms part of this specification. The drawings illustrate embodiments and together with the description explain principles of embodiments. Other embodiments and many of the intended advantages of embodiments will be readily appreciated as they become better understood by reference to the following detailed description. The elements of the drawings are not necessarily to scale relative to each other. Like reference numerals designate corresponding similar parts.

Fig. 1 is a schematic representation of the system;

Fig. 2 is a schematic representation particularly illustrating the second conveyor;

Fig. 3 illustrates the system seen from the second outlet; and

Fig. 4 illustrates the system seen from above.

DETAILED DESCRIPTION

The following description generally refers to any of Figs. 1-4, and a specific reference is made to figures illustrating specific features particularly well. The illustrated system 1 is for fish handling and particularly for a singulation process. The system comprises a first conveyor 2 extending between a first inlet 3 and a first outlet 4. A second conveyor 5 extends between a second inlet 6 and a second outlet 7. The second outlet is at the upper pulley 8 where the fish is emptied from the corresponding slot when the slot turns around the upper pulley.

At an interface 20, c.f. Fig. 2, fish is transferred from the first conveyor to the second conveyor, and at the second outlet 7, the fish can follow three different routes depending on a signal from the singulation sensor 24. The three different routes are particularly well understood in view of Fig. 4.

From the second outlet at the end of the second conveyor, the fish may follow three different routes, in the following referred to as first route defined by the re-circulation conveyor 30, second route defined by the re-orientation conveyor 13, and third route defined by the delivery conveyor 42. The fish is routed between the three conveyors 13, 42, and 30 with a pivoting lid moving between three positions allowing the fish to be received by one of the three conveyors 13, 42, 30. The first route directs the fish by the rejection re-circulation conveyor 30, c.f. Fig. 3. The disclosed re-circulation conveyor is in the form of a chute, i.e., defining a low friction surface on which the fish can slide.

The rejection re-circulation conveyor 30 sends the fish back to the first inlet and thereby recycles the fish. This route is followed when the singulation sensor 24 detects more than one fish in a single slot of the second conveyor. The route is triggered by a structure referred to herein as a rejection structure. The rejection structure comprises means for moving the recirculation conveyor 30 relative to the second conveyor to a position where the content of a slot can be emptied onto the re-circulation conveyor 30, when the conveyor belt reaches the upper pulley. Accordingly, all fish contained in the slot are emptied onto the re-circulation conveyor 30 and returned to the first inlet.

The second route directs the fish to a first point of delivery on a re-orientation conveyor 13, e.g., in the form of a chute c.f. Fig. 4. This route is followed when a re-orientation sensor, in this case constituted by the singulation sensor 24, detects a single fish in a single slot of the second conveyor and with the head and tail in a specific direction, e.g., head pointing to the right. The route is triggered by a structure referred to herein as a re-orientation structure. The re-orientation structure comprises means for moving the re-orientation conveyor 13 relative to the second conveyor to a position where the content of a slot can be emptied onto the re-orientation conveyor 13, when the conveyor belt reaches the upper pulley. Accordingly, all fish contained in the slot are emptied onto the re-orientation conveyor 13.

The re-orientation conveyor 13 makes a U-turn and thereby re-orients the fish and delivers the fish in a second point of delivery in a first buffer 32, c.f. Fig. 3.

The first buffer comprises a row of first-buffer-slots which each can store a single fish until it is delivered on a takeaway conveyor.

The third route directs the fish to a third point of delivery which is a position in a second buffer 33, c.f. Fig. 3 and 4.

This route is followed when the re-orientation sensor, still constituted by the singulation sensor 24, detects a single fish in a single slot of the second conveyor and with the head and tail pointing in a specific direction, e.g., to the left. The route is also triggered by the reorientation structure, i.e. again, the fish is routed between conveyor 13, 42, and 30 with a pivoting lid moving between three positions allowing the fish to be received by one of the three conveyors 13, 42, 30, and thereby depending on the orientation allowing the fish to be emptied onto the re-orientation conveyor 13, or onto the delivery conveyor 42, c.f. Fig. 4, or depending on the number of fish in a slot, to be delivered onto the re-circulation conveyor 30.

The delivery conveyor is in the form of a chute. Accordingly, all fish contained in the slot is emptied onto the delivery conveyor 42 and slides into the second buffer.

Also, the second buffer comprises slots, referred to as "second-buffer-slots". Each of these slots can store a single fish until it is delivered to the takeaway conveyor. In the embodiment of Figs. 1-4, the system comprises two takeaway conveyors, best seen in Figs. 3 and 4. The two takeaway conveyors 9 are on opposite sides of the first and second buffers, and each buffer can deliver to one or the other of the two takeaway conveyors.

In the embodiment of Figs. 1-4, the system comprises two buffers. However, a single buffer may also be implemented to receive fish both from the re-orientation conveyor and from the delivery conveyor.

The fish is received at the first inlet in the form of an irregular stream of arbitrarily oriented fish, and when the fish is delivered at the takeaway conveyor 9 or at the buffers 32, 33, it is in the form of a single-file stream of fish.

The first conveyor may be defined by a conveyor belt surface 10 driven by motors via pulleys. However, it may also be constituted by a low friction, a stationary, conveying surface 10 on which the fish slides due to a downward inclination from the first inlet to the first outlet. The first conveyor thereby forms a chute with no movable parts.

Referring particularly to Fig. 4, the illustrated first conveyor is a combination of a conveyor belt surface 10 defined by two separate conveyors, and a chute 10'. The first section of the first conveyor is constituted by a belt conveyor structure. This belt conveyor structure comprises two belt sections 2' and 2" each having an endless belt moved by pulleys 40 and motors 41. The second section of the first conveyor comprises a sliding section 2"' with a low friction, a stationary, conveying surface on which the fish slides due to a downward inclination towards the interface 20. The first section is horizontal, and the second section is inclined downwards towards the interface and thus towards the second conveyor. In the illustrated embodiment, the first outlet defines a longitudinal delivery edge 42 terminating the first conveyor and extending along the longitudinal side of an adjacent one of the dividing structures such that the fish is delivered into one of the slots in direction being transverse to the longitudinal direction and being transverse to the first conveying direction in the second section of the first conveyor. Deflectors 11, 12 are arranged along the first conveyor. Each of these deflectors are constituted by plate elements extending across the conveying path such that fish which slides on the conveyor bumps into the deflectors and becomes deflected.

The illustrated deflectors are stationary relative to the conveying path, and they are offset relative to each other along the conveying path. The angle of the deflectors relative to the conveying path is indicated in Fig. 4 by o, 0. In the illustrated embodiment, the angles are identical, however, each angle may be individual and differ from the other angles. Figs. 2 and 3 and 4 illustrate how the fish becomes oriented mainly in one direction after the contact with the deflectors. The second conveyor defines an inclination of the conveying path from a relatively low position at the interface 20 between the first and second conveyors to a relatively high position at the end of the second conveyor. The second outlet is therefore located at a higher position than the first inlet, and the first inlet is located at a higher position than the first outlet. The first outlet and the second inlet are in the same height. As best seen in Fig. 2, the second conveyor comprises a conveyor belt with an upper surface movable in a second conveying direction illustrated by the arrow 22. A row of adjacent slots 21 are defined by dividing structures 23 extending upwards from the upper surface.

Claims

1. A system (1) configured to convert an irregular stream of arbitrarily oriented fish into a single-file stream of fish, the system comprising a first conveyor (2) extending between a first inlet (3) and a first outlet (4), and a second conveyor (5) extending between a second inlet (6) and a second outlet (7), the first outlet and the second inlet defining an interface (20) where fish from the irregular stream of arbitrarily oriented fish is received from the first conveyor by the second conveyor thereby defining a downstream conveying path from the first inlet to the second outlet, wherein the second conveyor comprises a row of adjacent slots (21) configured to receive fish at the interface, and wherein the system comprises a rejection structure arranged to reject at least one fish from slots containing more than one fish.

2. The system according to claim 1, wherein the rejection structure comprises a singulation sensor (24) configured to detect the number of fish in each slot and to generate an electronic singulation signal, and wherein the rejection structure is configured to remove the at least one fish from a slot based on the electronic singulation signal.

3. The system according to any of the preceding claims, wherein the rejection structure is configured for rejecting all fish in a slot identified to contain more than one fish.

4. The system according to any of the preceding claims, comprising a re-orientation structure configured to reorient selected fish to define a single-file stream of uniformly oriented fish.

5. The system according to claim 4, wherein the re-orientation structure comprises a reorientation sensor (24) configured to identify an orientation of a fish in one of the slots and to generate an electrical orientation signal representing the orientation, and wherein the reorientation structure is configured to reorient the selected fish based on the electronic orientation signal.

6. The system according to claim 2 and 5, wherein the re-orientation sensor (24) is constituted by the singulation sensor (24).

7. The system according to any of the preceding claims, comprising a routing structure configured to route the fish from the second outlet to a selected one of at least three conveyors based on a signal from the reject structure or a signal from the re-orientation structure, the three conveyors being a re-circulation conveyor (30), a re-orientation conveyor (13), and a delivery conveyor (42).

8. The system according to claim 7, wherein the routing structure comprises a pivoting lid movable between three positions allowing the fish to be received by one of the three conveyors 13, 42, 30.

9. The system according to claim 7 or 8, wherein the re-orientation conveyor (13) forms a first point of delivery where fish is received from the second outlet, and wherein the reorientation conveyor (13) is configured for re-orientation of fish as they are conveyed on the re-orientation conveyor between the first point of delivery and a second point of delivery.

10. The system according to claim 9, comprising a first buffer comprising a plurality of first- buffer-slots for storing fish separated from each other, and wherein the second point of delivery is in one of the first-buffer-slots.

11. The system according to any of claims 7-10, wherein the delivery conveyor (42) is configured to receive the fish from the second outlet and to deliver the fish onto a third point of delivery.

12. The system according to claim 11, comprising a second buffer comprising a plurality of second-buffer-slots for storing fish separated from each other, and wherein the third point of delivery is in one of the second-buffer-slots.

13. The system according to claims 10 or 12, wherein each of the first buffer and second buffer is configured to deliver fish to at least one takeaway conveyor.

14. A method of transferring an irregular stream of arbitrarily oriented fish into a single-file stream of fish, each fish defining a longitudinal direction from a head region to a tail region, by use of a system according to any of the preceding claims, the method comprising delivering fish into an adjacent one of the slots, and returning fish from a slot to the first conveyor in case the slot contains more than one fish.

15. The method according to claim 14, wherein the fish is directed from the second outlet to one of at least three conveyors.