Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
2 1 ~
This invention relates to apparatus for the harvesting
and holding of live fish.
The collection of fish in flowing waters, using fixed
gear, has long been considered a desirable method of
harvesting a number of highly valued migratory fish
species. Such species as Arctic char, salmon, trout,
striped bass and eel spend some portion of their life cycle
in fresh water and it is there where they may be
conveniently collected. The live collection and holding of
some of these species is desired for purposes of securing
higher market prices or their use as sources of spawning
material for stock enhancement.
The collection of these and other freshwater species
has been conducted for millennia and as a consequence of
the variability of environments from which they have been
harvested, an astonishing array of harvesting systems have
been developed. These designs however, are typically used
in the broader, somewhat slower moving rivers
characteristic of the low topography of coastal plain
states on both sides of the Atlantic Ocean. Such ideal
conditions are not present in all regions and few designs
for river harvesting devices are suitable for use in faster
flowing rivers.
Fixed gear by its very nature is attached or anchored
to some bottom substrate and is normally deployed in
shallow rivers, estuaries and coastal areas. It is in
these areas that the largest concentrations of many highly
valued freshwater and coastal fish species abound. Major
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advantages of using fixed gear are: the low cost of
operation; proximity to the shore and processing
-- capability; and the capability of harvesting a live and
consequently absolutely fresh and higher valued raw
material. One specific design of net, named the fyke net
has been developed and extensively used in these
environments.
Several difficulties adversely influence the
effectiveness of harvesting gear in these coastal,
estuarine and freshwater environments.
One of such difficulties involves high velocity
waters. Some fish species move or migrate only when the
water levels are adequately hiqh so as to permit passage up
a river or along the reaches of an estuary. These higher
water levels are frequently associated either with
precipitation or tidal current-induced increases in water
flow velocity.
Another such difficulty involves debris. During
periods of higher water levels and velocities debris, e.g.,
leaves, branches and other plant material are washed into
the streams, rivers and estuaries. This detritus has two
adverse effects on harvesting effectiveness in these
waters. Larger material, e.g., logs, can remove or destroy
the harvesting device. On the other hand smaller
materials, e.g., leaves, can block the wings and body of
the existing harvesting devices causing an obstruction of
water flow and consequent insurmountable strain on the
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netting material which either is destroyed, washed away or
is distorted to a non-functional state.
Yet another difficulty involves high volume harvest.
In temperate waters, although diversity of fish species is
significantly less than in tropical regions, the enormous
concentrations of temperature species in spawning or
feeding migrations or aggregations requires that effective
harvesting devices be capable of accommodating and handling
large volumes of catch within short time frames.
A still further difficulty involves non-target by-
catch. Most existing devices are non-selective in the
species of fish they harvest, with the exception of limits
imposed either by the size of the mesh which they are
fabricated, for quite small fish, or the dimension of the
entrance funnel which may prevent large organisms from
entering.
Finally, there are regulatory restrictions as a
consequence of the previous difficulties with non-target
by-catch. Consequently, fisheries managers and regulators
have required either that the use of fyke nets not be
allowed in lakes or ponds and then only during brief
seasons when the most valued non-target species are not
present in estuarine or riverine waters. The most liberal
permitted usage is a deployment in which the net does not
occlude or harvest from at least one-third of the main
channel of the river or estuary.
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Some prior patents which may have some relevance to
the present invention include the following:
1) U.S. Patent No. 4,170,196 (October 9, 1979)
YONEYA, KIYOO, Kurobe, Japan;
2) U.S. Patent No. 4,079,698 (March 21, 1978)
Inventor: NEFF, GREGORY N., Dobbs Ferry, NY
BARRETT, PAUL C., Homestead, FL
3) U.S. Patent No. 4,003,338 (January 18, 1977)
Inventor: NEFF, GREGORY N., Dobbs Ferry, NY
BARRETT, PAUL C., Homestead, FL
4) U.S. Patent No. 3,852,908 (December 10, 1974)
Inventor: CHRISTOPHER, JOHN P., Islamorada, FL
5) U.S. Patent No. 4,244,323 (January 13, 1981)
Inventor: MORIMURA, SHINJI, Yokohama, Japan
and 6) Canadian Patent No. 1,093,401 (January 13, 1981)
Inventor: STREICHENBERGER, RUDOLPHE, Devin,
France
Existing designs of fyke nets are either submerged,
displaced or distorted by higher velocity water flows.
Existing devices have no means to handle large volumes of
catch and have been known to become bloated with catch,
both to the detriment of the live fish and with such weight
that it is unmanageable and a significant proportion of the
harvest is lost. Existing devices have demonstrated
significant problems of catching non-target species which
difficulty has caused restrictions on their season and
extent of use. Accordingly, the principal aim ~f the
present invention is to provide improvements to th~
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traditional design of fyke net to mitigate or substantially
eliminate these difficulties.
This invention is a highly effective harvesting and
live holding system for fish species, useful in static
waters but particularly effective in flowing waters. The
invention comprises a system with two mechanical components
and a method of use which achieves the above objectives.
The present invention provides a fyke net comprising:
a) a trap body tunnel open at one end and including a
plurality of inward narrowing diownstream funnels; b) wings
or leaders in the form of panels of vertically hung netting
extending from the trap body and adapted to be disposed
along the river or lake bottom; c) wing supports in the
form of stakes adapted to be erected into the stream or
lake bottom and adapted to maintain the shape and position
of the wings and to keep them erect in higher velocity
water currents; and d) a collection bag in the form of an
additional closed-end funnel of netting, situated behind
the body of the net at the narrow end of the funnels.
The present invention also provides a holding cage
comprising: a) a containment cage comprising a frame of
structural material and a mesh covering; and b) a flexible
bladder attached to the containment cage for loading with
a gas thereby to provide buoyancy for the containment cage.
The first mechanical component of the system is a
harvesting device which incorporates novel improvements on
an age-old design of the fyke net. The harvesting device
component of the system has four distinct but integrated
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elements. The first element is a trap body which is a
tunnel of netting, either of rectangular, square or round
cross-section which is open at one end which serves to
attract and trap the fish by means of inward narrowing
downstream funnels to prevent the escape of the fish which
have entered the trap.
The second element is a plurality of wings or leaders,
which are long panels of vertically hung netting extended
from the body of the net along the river or lake bottom to
intercept and guide the moving target fish species to the
net body.
The third element is a plurality of wing supports
which are vertical stakes which are erected, e.g., by
thrusting or hammering them into the stream or lake bottom,
and which serve to maintain the shape and position of the
.
wings and to keep them erect in higher velocity water
currents.
The fourth element is a collection bag which is an
additional tunnel of netting, situated behind the body of
the net at the narrow end of the funnels which provides
space in which volumes of the captured target species may
be retained.
The riverine fyke net of this invention is fabricated
of non-corroding metals and netting. It is designed and
fabricated effectively to divert, funnel and collect fish
moving or migrating in estuaries and rivers. The novel
improvements below enable a number of functional
advantages.
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The net wings are designed to be shaped by higher
velocity water flows tc provide a smoothly contoured
- channel to guide this target species into the body trap
section. When used in water depths exceeding the height of
the wing, a narrow roof of netting, projecting orthogonally
from the vertical wing on either side redirects fish
attempting to swim over the wing downwards towards the wing
and guides the fish along the wing. The vertical pipe
sections of the front frame of the trap body form concave
curves towards the rear of the net, conforming to the
curvature of the net wings channels formed by the
horizontal billowing of the wing netting in the river
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current.
The small mouth at the narrow of the funnel-shaped ;
non-return valve at the opening of the trap body has a
mechanism for deterring the entry of mammals which may
. .
succumb in the net. Such deterrent mechanism is a sharp
double prong which originates from the metallic frame
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surrounding this mouth and projects forward into the
expanding circumferences of the tunnel.
A specially designed rear frame enables rapid
detachment and replacement of collection bags during
periods of high volume harvesting activity.
The trap body frames have a square outline, preventing
movement of the net in turbulence.
The net mesh is oriented to hang in square mesh
configuration on the rear frames to reduce hourglass
narrowing of body net tunnel between frames.
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A special apron along the bottom of the net wings is
used to secure the wings to the bottom by ballasting the
apron, e.g., with available rocks, to prevent escapement of
fish under the bottom of the wings.
Specially designed supports shaped as a mirror image
figure "4" with double angular extensions from a vertical
pole use the force of the river on the net wing to drive
the support into the river bottom and enables the net wings
to remain erect and functioning as an eel barrier in high-
velocity water flow conditions.
A mechanism for facile attachment and removal of the
top of the wings at the support stakes constitutes simple
rings attached to the top of the wing which fits over the
top of the wing support stakes and provide the means
whereby the wings may be rapidly dropped from the support
takes to place the net in a non-fishing/no-obstruction/non~
operating mode which permits passage of other fish species
during periods when movements of target species are not
occurring and also provides for the facile cleaning of
leaves and debris.
Two unique fabrication methods are used for the
production of the fyke net of this invention. One method,
the net-to-net panel method, is to insert a small rope
through each mesh of net panels to be joined, providing a
positive method of joining which ensures greater integrity
of the join over that afforded by traditional hand sewing.
The second method, the neit-to-frame attachment method, is
by means of inserting or sewing a small rope into the
~1 ~2~39
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meshes of the netting which are closest to the support
frames and the attachment of the small rope to the frame by
various means, including plastic or wire wrapping material.
The second mechanical component of the system is a
holding cage for the captured migratory fish. This unit
has two principal elements. The first element is a
containment cage comprising a frame of structural material,
e.g~, wood, plastic or metal pipe and a covering material,
either closed weave fabric or open mesh configured of
netting, plastic or wire mesh. The second element is a
flexible bladder attached to the containment device into
which air or other gas may be injected to provide buoyancy
for the cage.
The submersible fish cage is fabricated of non~
corroding metals and netting. It is designed to contain
concentrated aggregations of more sedentary fish species
and smaller volumes of more active fish species and
particularly throughout the winter months in ice-covered
waters of more temperature regions. The novel improvements
over traditional designs permit a number of functional
advantages, as follows.
The frame is constructed of non-corrodible, hollow
tubular structural material which does not absorb water and
provides some buoyancy to the unit.
The frame may incorporate a skid or runner which is
used both to support the cage frame above the substrate on
which it may be dragged and to provide a sled surface for
retrieval of the cage from beneath ice.
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A hatch or means of access to the cage is afforded by
the use of a marine-grade "zipper" of non-corrodible
material, in a circular or square shape.
The cages may be attached to the body of the
harvesting device through means of a standard slot coupling
and may be removed from the trap at will to be replaced by
another cage or a net collection bag.
The material covering the cage may be either an open
fabric, e.g., a fibre, plastic or wire mesh, either with or
without a variety of protective coatings or partially of an
open fabric and partially of a closed fabric, e.g., a vinyl
sheeting (the closed sheeting is useful for protecting the
live contents of the cage from excessive light.
The lifting element is a flexible bladder which is
attachable to the cage and is of adequate volumetric size
so as to lift the cage and its contents when full in fresh
water.
The bladder may be equipped with a combination inflow
and over-pressure relief valve which permits inflation only
up to a marginal value over the ambient water pressure and
thereafter shuts off the inflow of air, as well as
exhausting excess air upon ascent of the cage.
Alternatively, the bladder may be equipped only with a
readily available separate over-pressure relief valve and
a simple one-way check valve on the inflation hose to
prevent loss of air accumulated in the bladder.
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The cage units may be attached to one another in
series such that a single inflation hose will suffice to ~
lift the whole series of cages. ~ ~:
In the accompanying drawings,
Figure 1 is a diagram of an assembled fyke net of this
invention in perspective;
Figure 2 is a composite diagram of a front frame
detail, both in front elevation and in side elevation; ;
Figure 3 is a diagram of square trap body loop frames
with rounded corners in front elevation;
Figure 4 is a composite diagram of a clamp frame for
attaching the trap body with the collection bag, both in
front elevation and in side elevation;
Figure 5 is a composite diagram of entry deterrent
mechanism for small mammals, both in front elevation and in
side elevation;
Figure 6 is a diagram in side elevation of a double
angle Figure "4" wing support;
Figure 7 is a composite diagram of an assembled
submersible cage, both in top plan view and in side
elevation;
Figure 8 is a diagram of a tubular frame configuration
in perspective;
Figure 9 is a diagram of standard connecting slot for
attachment to fyke net;
Figure 10 is a diagram on side elevation of a buoyàncy i .
bladder attached to a submersible cage; and
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Figure 11 is a diagram of combination controlled
inflow and exhaust valve for a buoyancy bladder.
The description of the drawings is self-evident from
the legends on the drawings and from the drawings
themselves.
Although the two mechanical components of the system
(the riverine harvesting net and the submersible live
holding cage) are discrete and unique onto themselves, it
is the combination of the two mechanical devices and the
method of their independent or conjoint use which permits
maximum effectiveness of the system. Consequently, the
~method of use of the system is also part of the present
invention.
The novel riverine fyke net invention may be utilized
in several different configurations, depending on the site
and species to be harvested.
A preferred embodiment of the invention is that
configured with the body of the trap at the apex or angle
of a "V" formed by the extension of two wings of any
length. In this configuration, the open mouth of the net
body faces the expected approach of tne target species. In
locations where there are limitations on the proportion of
the river channel which must remain unobstructed, this
configuration may be supplemented by the use of another
vertical wing or leader upstream of the net and extending
across the open region left open by the net below. This is
the configuration which is typically used to harvest fish
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21~r39
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migrating either upstream or downstream in fast flowing
streams or rivers.
An alternate configuration, particularly useful in
slower flowing waters, utilizes the same body and
collection device into which one end of a single wing or
"leader" is attached along to the centre axis of the first
funnel in the net body at one and projects from the body
along the same axis in the other direction as a barrier to
fish passage.
A third configuration situates a second body trap and
collection bag on the extreme far end of the singular wing
or "leader". It is on these latter two configurations that
the narrow net "roof" diverting flange on the leaders are
most effective.
Multiple units of the complete system of this
invention may be used to span large distances of water.
The net may be used in deeper water simply by increasing
the height of the wings and the front frame by which the
wings are joined to the body of the net.
The submersikle fish cage or a series of cages may be
filled with fish to the level permissible by the biology of
the particular species, and with the buoyancy bladder
inflated be moved across the surface of the water to a pre-
selected storage site. One end of the series may be
anchored using an attachment which will permit the cage
closest the anchor to float while the anchor is secured on
the bottom of the water body in which they are to be
stored. A boat attached to the other end of the series
~ 21~$39
14
maintains a small but constant tension on the series
maintains their linear orientation. The air is removed
from the bladders and the cages sink to the appropriate
positions on the bottom of the water body. The inflation
hose of the series is plugged and sunk with the cages,
after being marked with a surface buoy.
Retrieval of the series of cages simply requires the
use of the inflation hose pulled from the bottom by use of
a line from the marker buoy and the inflation of the
buoyancy bladders once again. The valves installed in the
buoyancy bladders permit all bladders to be fully inflated
and to exhaust excess air on ascent of the cages to prevent
over-inflation and bursting of the bladder.
The submersible cage may also be attached directly to
the trap body to accommodate increased volumes of catch in
short periods, where the velocity of the river or stream in
which the unit iB deployed is not excessive for the
increased drag produced by the cage. The flexibility of
configuration, interactive features and effectiveness of
the harvesting/live holding system is one of its major
functional advantages.
Trials of the net for the harvesting of freshwater
eels (Anguilla sp) have indicated that the live fish
harvesting and holding system of this invention is
significantly more effective than traditional methods
(collecting up to ten times (10 X~ greater weight of eel
than existing designs of eel nets). As the net is designed
to harvest downstream migrating eels which would be
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- 15
permanently lost to river system, the harvest is conducted
on a sustainable basis, preventing any depletion of the
river stock.
The present invention provides the following novel
features:
1. An integrated live harvesting and holding system
for migrating or motile fish species which comprises two
mechanical components; a highly effective harvesting device
and a submersible holding cage which may be used
independently or joined in a single unit.
2. Net wings of the harvesting component with
appropriate hanging ratios and depths of mesh designed to
be shaped by higher velocity water flows to provide a
smoothly contoured channel to guide the target species into
the trap body section.
3. A novel design of large mesh net or closed fabric
apron attached along the bottom of the net wings used to
secure the wings to the bottom by ballasting it with
available rocks.
4. A novel narrow roof of netting, projecting
orthogonally from the vertical wing on either side which,
in water depths exceeding that of the net wing, redirects
downward the fish attempting to swim over the top of the
wing.
5. Novel metallic supports for the net wings which
are shaped as a mirror image figure "4" with double angular
extensions from an upstream facing vertical pole to enable
~ 21~2~3~
16
the net wings to remain erect and functioning as a fish
barrier in high-velocity water flow conditions.
6. A novel mechanism for facile and rapid attachment
and detachment of the top of the wings at the support
stakes provides the means whereby the wings may be rapidly
dropped from the support stakes.
7. A novel front frame of the harvesting component
with a concave curvature which is the same as that for the
net wings to which the frame is attached when deformed by
the movement of higher velocities of water into the wing
netting.
8. Trap body frames with a square outline,
preventing movement of the net in turbulence.
9. A novel specially designed rear frame enables
rapid detachment and replacement of collection bags during
periods of high volume harvesting activity.
10. A novel collection bag with a frame similar to
that of the trap body which provides volume space to
prevent excessive crowding of the live catch.
11. A novel mechanism for deterring the entry of
mammals which may succumb in the net is installed in the
circular opening at the apex of the first funnel of the
trap body, being a sharp, double-prong which originates
from the metallic ring surrounding opening and projects
forward into the expanding circumferences of the net
funnel.
12. The small mouth at the narrow of the funnel-
shaped non-return valve alt the closed end of the trap body
2~ ~2~
may be stretched in tension with the novel use of an
elastic material on the slit-like opening for purposes of
- preventing the entry of non-target species.
13. A frame constructed of non-corrodible, tubular
structural material which does not absorb water and
contains adequate air when sealed to provide some buoyancy
to the unit.
14. A novel frame design which incorporates a skid or
runner which is used to both support the cage frame above
the substrate on which it may be dragged and to provide a
sled surface for retrieval of the cage from beneath the
ice.
15. A hatch or means of access to the cage as
afforded by the use of a marine grade zipper of non-
corrodible material, in a circular or square shape.
16. A cage being covered by an open fabric such as afibre, plastic or wire mesh, either with or without a
variety of protective coatings or partially of an open
fabric and partially of a closed fabric such as a vinyl
sheeting.
17. A buoyancy lifting bladder for providing buoyancy
to the cage comprising a flexible membrane resistant to
fluid pressures which is attachable to the cage and of
adequate displacement volume so as to lift the cage and its
contents when full in fresh water.
18. A novel combination inflow and over-pressure
relief valve which permits inflation only up to a marginal
value over the ambient water pressure and thereafter shuts
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18
off the inflow of air, as well as exhausting excess air
upon ascent of the cage.
19. A submersible cage unit which may be attached to
others of the same design in series such that a single
inflation hose will suffice to provide buoyancy and lift to
the whole series of cages.
20. A submersible holding cage which may, in a novel
manner, be attached to the body of the harvesting device
through means of a standard slot coupling and may be
removed from the body trap at will to be replaced by
another cage or a net collection bag.
21. A novel method for the join of net panels using
a small rope inserted through each mesh on the edges of the
net panels to be joined, providing a positive method of
joining which ensures greater integrity of the join over
that afforded by traditional hand sewing.
22. A novel method of joining the netting of the
harvesting device to the trap body frames by the insertion
or sewing of a small rope into the meshes of the edge or
portion of the netting which are closest to the support
frames and the attachment of the small rope to the frame by
several means including plastic or wire wrapping material.
23. A novel method of orienting the netting such that
hangs in a "square mesh" configuration on the rear frames
to reduce "hourglass" narrowing of the body net tunnel
between frames caused by the downstream drag on the net
body from flowing water.
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