FIELD OF INVENTION

The invention relates to trawl nets for trawl fishing and in particular self-spreading trawl net technology.

TECHNICAL BACKGROUND AND PRIOR ART

Published International Patent Applications (PCT) having publication numbers: WO 97/13407, WO 98/46070, WO 99/39572 and WO 03/081989 are hereby incorporated by reference and teach a technology produced by the present applicant, Hampidjan hf., of Iceland and sold under the trade name "Helix" and generically known in the industry as "self-spreading trawl technology". In brief, the teachings of the above identified published PCT applications is used to create mesh bars having a plurality of cambered sections oriented and configured so that, when a trawl based on said mesh bars is towed through a body of water, the cambered sectioned mesh bars generate lift vectors mainly directed (i) normalized to the long axis of the cambered sectioned mesh bar, and (ii) away from one side or other of the plane of the netting panel generally formed by the cambered sectioned mesh bars. When the cambered sectioned mesh bars are oriented in such a way that the generated lift vector is mainly directed outward, away from the axis of the trawl, the mesh bar has come to be known as, and is hereinafter referred to as, a "self-spreading mesh bar". When a netting panel includes cambered sectioned mesh bars, and the cambered sectioned mesh bars forming the netting panel mainly are "self-spreading mesh bars", the netting panel has come to be known as, and is hereinafter referred to as, a "self-spreading netting panel".

The above referenced PCT applications disclose different self-spreading mesh bars, which in some embodiments advantageously can be made by forming a rope with a loose corkscrew-shaped pitch with helical grooves. Different threads, such as twines, cords, braided cords, cables or ropes, may be twisted, during assembly of mesh bars which form a trawl's mesh cells, into a loose, corkscrew- shaped pitch with helical grooves. In the most typical embodiment, the mesh bars in a mesh cell of a self-spreading netting panel are configured such that the handedness of the pitch (left- or right- handedness) of one mesh bar is in the opposite direction as its mating mesh bar, as it explained in greater detail in the above referenced applications, in particular WO 97/13407. In the case of a trawl with conventional rectangular (diamond-shaped) mesh cells each formed of four mesh bars, the opposite, e.g. parallel, mesh bars of any mesh cell act as mini-hydrofoils or wings in concert in operations. Such opposite bars (whether formed of a series of twisted strands or of a single twisted strap), are characterized as having a common lay direction when viewed in an axially receding direction (either right-handed or left-handed lay) that is opposite to that associated with the other two mating (e.g. parallel) mesh bars in the mesh cell.

The above mentioned PCT applications further teach that the cambered sectioned mesh bars may be used in a trawl to form at least a front end of the trawl from the cambered sectioned mesh bars

oriented in such a way that lift vectors generated by the cambered sectioned mesh bars mainly are directed outward, away from the center of the trawl (i.e. forming the trawl mainly from several "self-spreading mesh bars"), thus forming a "self-spreading trawl".

In some embodiments, the above identified PCT applications teach that: a) the bottom panel of the front end of the trawl is optionally mainly formed from cambered sectioned mesh bars oriented so that their lift vectors mainly are directed inward, toward the center of the trawl, or so that their lift vectors are neutralized; and b) side panels of the front end of the trawl may include mesh bars forming netting panels having greater outwardly directed lift vectors than netting panels formed of mesh bars in the top or bottom panels of the front end of the trawl; and c) the back end of the trawl may be constructed of mesh not formed of cambered sectioned mesh bars, while the front end mainly includes mesh formed of cambered sectioned mesh bars oriented and configured in such a way that lift vectors formed by the cambered sectioned mesh bars during towing of the trawl through a body of water mainly are directed outwardly, away from the center of the trawl.

These technical solutions are intended to give the trawl an opening which is more wide horizontally than vertically. Such horizontally wide mouth trawls are very useful in many applications, as many commercially important fish species caught by trawl fishing swim in schools that even though they may be large and dense are often of limited height. That is, the fish school occupies a relatively limited stratum of water in the ocean, and adjacent strata may contain other fish species which are not being targeted and by-catch of such other species is generally undesired. Therefore, in order to use the trawl opening most efficiently, is generally advantageous, e.g. in the North Pacific Pollock fishery but as well in many other situations and locations, to have a trawl opening which is wider horizontally than vertically, and such shape will generally make most efficient use of the overall practically available area of the trawl opening.

A problem not addressed by the above identified publications or elsewhere in the known art is that in order to obtain the desired mouth shape for a wide body trawl, such as is common in the Alaska Pollock fishery, and is becoming common in other fisheries, the trawl construction becomes such that the back end opening is poorly maintained, and economy of fishing operations is significantly decreased.

None of the known art teaches the invention described herein below.

SUMMARY OF INVENTION

Briefly, the present invention teaches a "self spreading trawl" having at least a top and bottom panel formed of "self spreading mesh bars", the trawl including a front end and a back end, wherein at least the top panel of the front end comprises:

^

a) an aft front end panel section; and b) forward front end panel section,

the aft front end panel section formed of a "self spreading netting panel", and the forward front end panel section formed of a netting panel having less outwardly directed lift than the netting panel forming the aft front end panel section, whereby trawl mouth opening has a bettered horizontal opening dimension relative to vertical opening dimension, bettered uniformity of vertical opening dimension, both with concurrent better maintained back end opening. That is, the forward front end panel section is preferably formed of a netting panel including mesh that is mainly formed of mesh bars capable of generating less (including none) lift vectors directed outward, away from the center of the trawl when towed through the water environment than the mesh bars mainly forming the aft front end panel section, whereby the trawl shape includes a trawl mouth having a mouth vertical dimension that is better reduced in scale relative to a mouth horizontal dimension while concurrently conserving back end vertical dimensions.

In another embodiment, the mesh forming the forward front end panel section of the trawl described supra mainly includes cambered sectioned mesh bars oriented so that lift vectors generated by the cambered sectioned mesh bars mainly neutralize each other, i.e. a "neutral netting panel section", whereby, the mesh panel forming the forward front end panel section generates less (including none) outwardly directed lift than does the mesh panel forming the aft front end panel section.

Thus, in the presently preferred embodiment, the mesh bars forming the mesh of the forward front end panel section of a trawl of the present invention either: a) mainly neutralize each by being oriented so that mesh bars generating lift vectors mainly directed outward, away from the center of the trawl (i.e. "self spreading mesh bars") are mainly included in individual mesh with a similar number of cambered sectioned mesh bars generating lift vectors mainly directed inward, toward the center of the trawl (i.e. "self collapsing mesh bars"); or b) mainly are formed from conventional rope having insignificant lift vectors; and/or c) mainly are formed from rope having lead (or other heavier than water material) in the rope so as to reduce upwardly (toward the surface of the body of water) directed outwardly oriented lift vectors generated by the mesh bars.

The trawl of the present invention mainly is an all point taper trawl from the circumferential mesh row defining the fishing circle to the end of the trawl. That is, the trawl is constructed with no

"point and bar" taper in the trawl from the fishing circle row (i.e. the first region of the trawl aft of the trawl's mouth, also defined as the first region of the trawl most proximal the trawl's mouth where there is a complete, 360 degree, envelope of netting forming the trawl) to the most aft region of the trawl (in the back end). The all point taper of the front end is preferably formed of radial pattern mesh, as described in WO 03/081989. Radial pattern mesh in a trawl indicates that the size of mesh cells is progressively reduced from front to back of the trawl through progressively shorter mesh bars. Thus, within an individual mesh cell of a radial pattern trawl (or radial pattern portion thereof) the two mesh bars nearer the mouth of the trawl 13 are longer than the two mesh

^

bars further from the mouth. One characteristic of such a trawl is that despite tapering of a panel, the number of mesh cells across the panel remains constant throughout any portion with radial pattern. Thus, such portion of a trawl assembled using a radial pattern lacks any abrupt change both in mesh bar length, e.g. halving of mesh bar length, or in the number of mesh cells across a panel.

None of the known art has proposed a trawl where the front end of the trawl aft of the fishing circle is all point taper (or mainly all point taper) in combination with a back end that is all point taper (or mainly all point taper).

Fig. 1 shows a top plan view of the trawl 1 of the present invention showing the upper (or top) side of the trawl of the present invention having a front end 2 and a back end 3. The distal end part of the back end 3, comprising the codend , is not shown, i.e. the back end extends to a closed end conical or sac-like terminus referred to as the codend or brailer bag, to collect the catch.

The upper side of the trawl of the present invention includes top panel 4 having top panel forward front end panel section 5 and aft front end panel section 6.

Aft front end panel section 6 includes subsections 6a, 6b, 6c and 6d defining progressively smaller mesh sizes, respectively. Back end 3 includes smaller mesh sizes than those forming subsections 6a - 6d, Aft front end panel sections 6a - 6d mainly include "self spreading mesh bars" 31 and 32, thus forming "self-spreading netting panels" 34, and preferably are formed entirely of "self- spreading mesh bars". In this way, aft front end panel sections 6a - 6d serve to provide opening forces directly to and most proximal to back end 3 so as to better maintain the opening of back end 3 under field conditions, including heavy loading.

It should be noted that intersections between the above defined sections of the trawl (forward front end, aft front end and back end) need not be precisely defined by an abrubt or stepwise change in the mesh bar type and/or mesh size, and the ratio between the lengths of the sections can vary between different embodiments of the trawl of the invention. In some embodiments, the forward front end is about equal in widest width as the aft front end panel section. In other embodiments the widest width of the forward front end panel section may be in the range between 50% and 800% of the widest width of the aft front end panel section.

In the presently preferred embodiment, top panel forward front end panel section 5 mainly is formed of neutralized non-self spreading mesh bars 21 and 22, forming a neutralized netting panel section as described supra, so as to form a "non-self spreading netting panel portion" 35. However, selvedge mesh bars 33 are preferably of a larger diameter than mesh bars 21, 21, and also are preferably "self spreading mesh bars", so as to provide improved horizontal opening to the trawl mouth as well as to provide stability to the sides of the trawl, thus improving trawl mouth uniformity and symmetry of shape.

^

Meshes 19 are included in the "fishing circle" of the trawl, as described supra. In the preferred embodiment, the trawl of the present invention includes a front end having a portion aft (toward the back of the trawl) of the fishing circle that mainly is constructed of "all point taper" netting panels in combination with a back end that mainly is constructed of "all point taper" netting panels.