Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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DEVICE AND SYSTEM FOR TREATMENT OF FISH
Field of the invention
The present invention relates to a device at a fish farm net cage to treat or
vaccinate
farmed fish against parasites and disease, where the device comprises a tank
with a
treatment agent in which the fish shall be treated and where the tank
comprises a
conveyor mechanism for the fish in the tank. The invention also relates to a
method for
continuous treatment of farmed fish in an aqueous environment in such a device
and a
system comprising such a device.
1 0 Background of the invention
Fish farming is more and more common and today makes up a large and important
industry. Attacks of disease and/or parasites lead to large economic losses
and also a
considerable suffering for the fish.
The description of the invention given below is exemplified with the farming
of salmon
and with salmon lice as the damaging parasite as this currently represents a
considerable challenge for the fish farming industry in Norway, but the
invention
comprises all forms of bath treatment of fish.
During a disease attack, and in particular infectious diseases, it is common
to treat the
farmed fish with medication to fight the disease. The medication can be
administered
to the fish in several different ways, where the most common for farmed fish
is injection
of the medicine directly into the fish, oral administration of the medicine as
an additive
2 5 to the feed that is given to the fish, or that the medication is added
to the aqueous
environment (bath treatment) in which the organisms live.
One aim of the present invention is to provide a device, method and system to
be able
to administer treatment agents to farmed fish at the fish farm installation.
The agents
3 0 are administered to an aqueous environment through which the fish is
led.
In addition to the device and the methods according to the invention being
used to treat
a disease for farmed fish, the device can alternatively be used to give a
preventative
effect, such as that different vaccines are administered (dip vaccination), or
that the
35 agents are directly aimed at the cause of the disease/infection, such as
bacteria, virus,
amoeba, parasites etc., to kill these or to prevent an attack.
SUBSTITUTE SHEET (RULE 26)
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We will also emphasise that "treatment" does not necessarily imply that a
chemical or
medicine is added to the aqueous environment. In some cases one can use fresh
water in the tank, for example to fight amoebae, and in other cases one can
change
the temperature of the aqueous environment, such as, for example, that one
raises or
lowers the temperature.
For the treatment of lice, either preventatively to prevent that an aquatic
environment
becomes infected by lice, or to prevent the lice being attracted to the fish,
or to prevent
the lice getting fastened onto the fish or to remove lice that are fastened to
the fish,
there are known techniques to supply so called salmon lice agents to the water
in
which the fish live. The salmon lice agents are mixed into or added to the
water, either
directly or indirectly to the net cages where the fish are.
Today, there are different solutions where the net cage is surrounded by a
cloth or
tarpaulin to demarcate the aqueous environment, and in some cases the net cage
is
hoisted up so that the volume of water one wants to treat becomes somewhat
smaller.
Regardless, it is a problem that the volume of water is very large, which
means that a
considerable amount of chemicals must be used for the treatment. Furthermore,
such
systems are to a more or less extent open, and one does not have complete
control of
the contamination caused by the chemicals to the environment, whether it is to
the
ocean bed or the aqueous environment surrounding the net cage installations.
There are also solutions where the fish are transferred from the net cage to
containers
or tanks, for example, tanks on board well ships. Such systems are closed in
that one
has control of the water and the treatment agents that are supplied and are
removed
from the system.
W02010/087722 describes a unit for the transfer of fish from one net cage to
another
via a chute that is led into the wall section of the net cages. Water from the
one net
cage will flow through the unit and to the next net cage. The treatment agent
is added
in the chute. This solution makes dewatering of the fish impossible during the
transfer
to and from the tank, and with no regulation of the residence time in the
treatment unit
with a conveyor mechanism that has a pre-determined direction and speed.
Therefore,
this solution will lead to discharges of the treatment agents to the
surrounding
environment and an inexact residence time for the fish in the treatment means.
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US 4,363,290 describes a solution where fish are led into a reservoir that
contains a
treatment agent. This solution can not be used for continuous treatment of
fish in the
vicinity of a fish farm. Similarly, use of US 4,363,290 leads to the fish
lying dry on the
conveyor that brings them down into the bath. This is very arduous for the
fish and
limits the survival rate for the fish that shall be treated. For salmon and
trout such a
treatment would lead to an unacceptable death rate if the unit was used at a
farm for
edible fish.
N0332298 describes a solution where the fish are pumped through an arched
pipeline
1 0 where a zone of the pipeline contains a treatment agent. This solution
does not have a
conveyor mechanism and the fish will therefore not have an accurate residence
time in
the treatment agent. This weakness is particularly obvious when the volume of
the
treatment bath is large in relation to the size of the fish.
1 5 The present invention provides a device and a solution that represents
an
improvement of these systems, and in particular the aim of the invention is to
provide a
solution where the treatment of the fish takes place continuously in a loop,
where the
residence time in the treatment bath can be regulated and where there is a
total
replacement of the aqueous environment before entering the treatment tank and
at the
2 0 transfer from the treatment tank.
With the term "continuous" in the context of this invention is meant that the
fish are led
from the net cage and over into a treatment unit, through the treatment unit
and out
again of the treatment unit in a continuous process, i.e. as an on-line
treatment in a
2 5 loop. This does not prevent that the conveyor mechanism can be operated
and be
stopped at intervals to optimise the treatment time or other operating
parameters.
In a presently preferred solution the device for the treatment of farmed fish,
also
described as the treatment unit, comprises a screw tank, for example of the
Helix tank
3 0 type, where the fish are fed in at the one end of the tank, are treated
with different
agents as they are continuously being fed through the aqueous environment of
the
tank, until they are fed out of the other end of the tank. The residence time
in the tank
can be regulated, and added chemicals and removal of water and other agents to
and
from the tank can be regulated also.
The difference between the solution according to the invention and solutions
that are
known from prior art is that the system according to the invention is
"continuous", while
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the known solutions are batch or fed batch-wise, i.e. one carries out the
treatment in
the net cage or in the space of a well boat. In the batch-wise treatments the
fish are
first placed in a treatment volume, thereafter the agent is added and the
agent is
thereafter diluted again.
With a continuous treatment there will be a treatment agent in the tank. The
fish are
added to the tank and the residence time in the treatment tank for the fish is
regulated
by the conveyor mechanism that leads the fish through the tank so that the
residence
time for each fish is approximately the same, i.e. that the fish are fed out
of the tank in
approximately the same order as they come into the tank. Furthermore, the tank
volume is relatively limited since only a limited number of the fish in a net
cage at any
given time will be in the treatment tank. This represents a considerable
advantage as
the consumption of chemicals can be reduced, at the same time as one can
precisely
control the content of the tank.
Summary of the invention
In a first aspect the present invention relates to a device for the treatment
or
vaccination of farmed fish against parasites and diseases at a fish farm where
the
2 0 device comprises a tank with a treatment agent in which the fish are
treated, and
where the tank comprises a conveyor mechanism for the fish in the tank,
characterised
in that the conveyor mechanism has several blades that bring the fish through
the tank
from the inlet to the outlet in a pre-determined direction and speed to give
the fish a
pre-determined residence time in the tank, and where the device comprises
means for
2 5 the transfer of the fish from a first body of water via dewatering
means and the inlet to
a new water environment in the tank and via dewatering means and an outlet to
a new
body of water.
In one embodiment the conveyor mechanism comprises more than two blades.
In one embodiment the blades of the conveyor mechanism are fitted onto a chain
or
driving belt that is driven forward for the transport of said farmed fish
through the tank.
In one embodiment the tank is a screw tank, preferably of a Helix tank type.
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In one embodiment the tank has a vertical, cylindrical-circular shape with
radial blades
fastened to a central axis that splits the treatment volume into sections, and
where the
pre-determined speed and direction are regulated by the rotation of said axis.
In one embodiment the device comprises further conveyor mechanisms for the
transport of fish to/from net cages and the tank, where said conveyor
mechanisms
optionally comprise a conveyor belt and pumps such as a Mamut pump, vacuum
pump, ejector pump or centrifugal pump.
In one embodiment said dewatering means is placed between the first net cage
and
the tank, and/or a sorting machine between the tank and the second net cage.
In one embodiment said sorting machine(s) are not for primary straining, but
is placed
between the dewatering means and the tank or between the last dewatering means
at
the tank outlet and the net cage.
In one embodiment the tank comprises one or more inlets for the supply of
liquid and
different treatment means.
In one embodiment the device comprises several tanks set up to carry out
several
treatments of said fish.
In one embodiment the tank comprises one or more sensors for the measurement
of
different parameters such as temperature, pH, 02 and ORP, concentration of
different
treatment agents, density of organisms in the tank (fish counter), and also a
measuring
unit for the amount of water and dosing pumps with a measuring unit for the
amount of
additions.
In one embodiment the device comprises means for automation, such as means for
the regulation of the supply and exit of the number of fish to/from the tank,
means for
the regulation of the through flow of liquid and residence time, means for the
regulation
of the supply of, and concentration of, treatment agents, etc.
In a second aspect the present invention relates to an application of a device
as given
above for the treatment of farmed fish in a net cage, where said fish are
transferred
from one net cage via dewatering means and an inlet to a treatment tank set up
so that
the fish are taken up in a new aqueous environment and that said fish are
transported,
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in a pre-determined direction and speed, by a conveyor mechanism with blades
through the treatment tank and that the fish, after the treatment, are led out
of the tank
via dewatering means to a new aqueous environment.
In one embodiment the residence time of the fish in the tank can be regulated.
In one embodiment the treatment agent is supplied to the tank via a number of
inlets
so that the aqueous environment in the tank becomes homogenous.
In one embodiment said treatment is set up to prevent and/or treat diseases
for said
farmed fish.
In one embodiment said treatment is set up to remove parasites from the fish.
In one embodiment said parasite is lice, preferably salmon lice, and that the
treatment
comprises treating the fish with an adequate agent which effectively fights
the lice
and/or removes the lice from the fish, where said agent is chosen from
pyrethroids,
pyrethrum, organophosphates, chitin inhibitors, avermectines and hydrogen
peroxide
where said hydrogen peroxide is preferably added to seawater or water with a
low salt
content.
In one embodiment said treatment is for the removal of amoebae and where said
water
in the treatment is fresh water or water with a low salt content.
In one embodiment, where said parasite is lice, preferably salmon lice, the
treatment
comprises treating the fish with water with added ozone.
In a third aspect the present invention relates to a system for the treatment
of farmed
fish from a net cage characterised in that the system comprises a treatment
device as
given above, arranged as a part of a floating installation and where the
treatment
device comprises a tank with a treatment agent in which the fish are treated
and where
the tank comprises a conveyor mechanism for the fish in the tank,
characterised in that
the conveyor mechanism has several blades that bring the fish through the tank
from
the inlet to the outlet at a pre-determined direction and speed, to give the
fish a pre-
determined residence time in the tank, and where the device comprises means
for the
transfer of the fish from a first body of water via a dewatering means and the
inlet to a
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new aqueous environment in the tank arranged in said floating installation and
via
dewatering means and an outlet to a new aqueous environment.
In one embodiment said floating installation is a vessel, such as a ship.
In one embodiment said floating installation is a raft.
In one embodiment the conveyor mechanism is a screw fitted in a screw tank.
In one embodiment the screw in said screw tank can be detached from the tank.
In one embodiment the tank is fitted with a lid or a cover that is placed over
the tank as
the screw is removed.
In one embodiment, where said vessel is a ship, the screw in said screw tank
can be
removed from the tank.
In one embodiment the tank is a vertical circular cylindrical tank with radial
blades.
In one embodiment the tank is on board a boat and where a number of the radial
blades can be dismantled when the boat is used for purposes other than that
described
in claim 19.
A representative device according to the invention will be described below
with
reference to the enclosed figures, where,
Figure 1 shows a perspective outline of a principal diagram of a device
according to
the invention.
Figure 2 shows an embodiment where a screw tank is used for on-line treatment
of
farmed fish.
At a net cage installation which encompasses a number of net cages 12, a tank
14 is
placed in the loop for the treatment of fish from the net cages 12. In the
description of
the example given below, the treatment is exemplified by the removal of salmon
lice
that have become fastened to the fish, but the device 10 can be used for any
bath
treatment of fish.
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The treatment is not carried out in the net cages 12 themselves, but the fish
are
transferred via dewatering means 13 to a separate treatment unit, i.e. a loop
("on-line")
is established through which the fish are transported and this loop comprises
at least
one tank 14. As the tank is used to take up water with a treatment agent, the
term
"treatment unit" is also used about this tank 14. Such a tank 14 can be
permanently
arranged in the vicinity of the net cages 12, but it is preferably mobile with
regard to the
net cage installation, and it is preferably placed on board a raft or barge,
or it can be an
integrated part of a vessel such as a ship.
The transfer of fish from the net cages 12 to the treatment unit or tank 14
can be
carried out in any suitable way and the invention is not limited to how this
is carried out.
In the transfer between the net cage and tank, the fish is dewatered, i.e. the
fish are
separated from the aqueous environment they were in and are transferred to a
new
aqueous environment. Different such means 13 can be used for the dewatering of
the
fish and in the different embodiments, grids and/or sorting machines are used.
One also seeks to achieve an efficient transfer of the fish from the net cage
12 to the
tank 14 and from the tank 14 to the net cage 12, at the same time as the fish
are
treated as gently as possible. To avoid getting a replacement of the water in
the
different net cages 12 and the tanks 14 a transport system that ensures
dewatering of
the fish is used as mentioned, i.e. the fish are separated from the water they
were in
and are transferred to a new aqueous environment. Such dewatering means 13 can
be
arranged as grooves or grids, or openings in the pump system so that one
achieves
that the organisms are separated from the aqueous environment in which they
were
originally.
As an example of a dewatering means 13 a sorting machine is shown in figure 1.
Water and fish are pumped from a net cage 12' by, for example, a pump 15 via
the
sorting machine. In this sorting machine the water is drained at the same time
as
unwanted fish are removed. For example, one can remove small fish, such as
small
pollack and wrasse so that these are not led to the treatment unit 14. One can
remove
the pollack while the wrasse is returned (without going via the treatment
tank) to one of
the net cages 12". A fish counter can be placed between the sorting machine
and the
treatment unit 14, for the counting of the fish that are led into the
treatment unit 14.
Alternatively, a such fish counting is carried out at a different place in the
process, for
example, in the treatment unit 14.
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The fish enter the treatment tank 14 via one or more inlets 14a and are
transferred to a
new aqueous environment, i.e. the one in the treatment tank 14. The aqueous
environment which is in the treatment unit 14 is particularly chosen
considering the
treatment the fish is to be subjected to. For removal of lice the water can
contain
agents that are effective in the treatment of salmon lice, such as
pyrethroids,
pyrethrum, organophosphates, chitin inhibitors, avermectines, hydrogen
peroxide and
ozone. The water contains sufficient amounts of one or more of such treatment
agents
for an effective delousing to take place during the time the fish stay in the
tank 14. The
loop-characteristic of the system makes it possible to use ozone as an agent
where
previously, due to a rapid taking up in large bodies of water one could only
use
hydrogen peroxide.
The residence time in the tank, i.e. how long time a given fish stays in the
tank from
entering the tank till it is fed out of the tank, can simply be regulated by
the conveyor
mechanism. For a helix-tank the blades, i.e. the part of the screw thread
which is
submerged into the water, and the flow of water will push the fish through the
tank, and
the speed of this feeding can be set by regulating the speed of rotation of
the shaft to
which the blades are fastened.
Furthermore, the tank is fitted with a number of inlets and outlets to supply
or remove
water and/or treatment agents, or other components, to and from the tank. A
screw
tank is shown in figure 2 with inlets, such as the inlet 14e for the dosing of
water, inlet
14f for the dosing of oxygen, inlet 14g for the dosing of treatment agent.
Also shown in
figure 2 is the set up 14h for the removal of protein, heat exchanger 14i,
mixer 14j,
sensors 14k, straining grid 141 and overflow 14m.
In some embodiments the temperature of the water bath is important and the
tank 14 is
then fitted with means to be able to supply water at any temperature to the
tank 14. In
some embodiments the tank is insulated so that the temperature of the water is
maintained for a long time period. It is also possible to use a cooler (14j)
to lower the
temperature in the treatment bath. Then, one can carry out the treatment with
oxygen
radicals, such as hydrogen peroxide and ozone during the summer. In today's
method
with hydrogen peroxide in a well boat one can not always treat fish during the
summer
because of the unwanted effects of hydrogen peroxide on the fish at high
temperatures.
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It is preferred that the tank is fitted with a number of sensors 14k, where
these are
arranged and set up so that they can monitor different parameters. This can be
parameters such as pH, 02 and ORP, temperature of the water, salt content of
the
water, the concentration of different treatment agents, the number of
organisms in the
water, etc. In a preferred embodiment sensors are arranged that can monitor if
lice are
fastened to the salmon, i.e. so that one gets a picture of whether the
treatment is
finished.
It is possible to divide up the tank in different zones so that different
treatments can be
given in the different zones. However, it is presently preferred, if the fish
shall be
subjected to different treatments, to carry this out in separate tanks 14
which are
connected in series.
The treatment water can be supplied to the treatment tank 14 by the help of
pumps so
that the mixture becomes homogenous (for example, with respect to the
concentration
of treatment agents) throughout the whole tank 14. It is also possible to add
treatment
agents at different locations in the tank 14 so that one can, for example,
amplify the
effect if the treatment agents are weakened or consumed in the treatment.
The essential element of the device according to the invention is that one has
an on-
line treatment, i.e. the fish are fed evenly and gradually through the
treatment unit
itself.
