WO1998058537A1

WO1998058537A1 - Selective fish hook

Info

Publication number: WO1998058537A1
Application number: PCT/NZ1998/000086
Authority: WO
Inventors: Paul Daniel Louis Barnes
Original assignee: Paul Daniel Louis Barnes
Priority date: 1997-06-25
Filing date: 1998-06-17
Publication date: 1998-12-30
Also published as: AU7943698A; NZ328189A

Abstract

A fish hook of a kind having a hooking portion (or 'bight') which may optionally have one or more barbs or other retaining means thereon, the bight having a distal sharp region, and a shank wherein either integrally formed from said shank or provided as an attachment there is a sharp ended projection of finite distance, the projection extending from the shank away from the distal sharp region of said bight.

Description

SELECTIVE FISH HOOK

TECHNICAL FIELD

The present invention relates to a selective fish hook. BACKGROUND OF THE INVENTION

Currently most of the worlds 's fisheries are considered to be fully developed, over exploited or depleted and at risk of a collapse in the stocks.

Fisheries manages worldwide have identified that a significant level of wastage occurs in both the commercial and recreational fisheries and have been actively promoting the development of more selective fishing technology capable of targeting fish above the size that produces the optimum yield per recruit, can reduce the catch of fish below any Minimum Legal size and also reduce any other forms of wastage or losses to the fish stock caused through the act of harvesting fish for reward or sport.

A significant portion of the fish harvested worldwide are taken by using fish hooks. This application concerns a new selective fish hook or appendage attached to an existing hook that has considerable benefits over any previous art in both the recreational and commercial fisheries that use fish hooks to take their catch. An additional benefit is that the incidence of gut hooking, which is another cause of wastage, is significantly reduced. The perfect solution to fisheries management problems concerning wastage is to catch only the size of fish desired, all of which are in top quality condition.

In one aspect the present invention provides a device, which when attached to (or integrally formed as part of) a fish hook, can significantly reduce the number of undersized fish caught and also correspondingly increase the number of fish caught that are above the legal size limit. By changing the configuration of the device (and particularly where the device is not integrally formed as part of the fish hook but can be attached thereto) the selectivity of the hook can be further altered allowing increases to be made to the size limit without increasing the by-catch of unwanted undersized fish. Therefore as an attachment a main function of the device is being able to preset or alter the selectivity of fish hooks the device is fitted to. A further benefit is that fish taken on hooks fitted with the device are much less likely to be gut hooked. Thus all fish over the minimum legal size are landed in a top quality condition, and the reduced amount of undersized or any unwanted legal sized fish can be returned to the water with a much improved chance of survival. (Gut hooking has been found to a major cause of mortality in released fish). BRIEF SUMMARY OF THE INVENTION

In a first aspect the present invention consists in a fish hook of a kind having a hooking portion (or "bight") [which may optionally have one or more barbs or other retaining means thereon], and a shank wherein either integrally formed from said shank or provided as an attachment there is a sharp ended projection of finite distance, the projection extending from the shank (in preferably the general plane of the hook) away from the distal sharp region of said bight.

Preferably said finite distance is chosen with a view to selectivity of fish sizes, for example, a distance of from say 15 mm to 60 mm (eg; 20 mm or 40 mm).

In some forms of the present invention said projection projects from said shank from between the ends thereof whilst in other forms said projection projects away from said shank at or adjacent the snood or line attachment aperture, eyelet or other means thereof. Preferably said projection is in the form of a wire or the like member which, if being provided as an attachment to a fish hook, includes means which passes through the eyelet or opening of the fish hook for line or snood attachment and thereafter clamps to said shank, (for example, in the form substantially as hereinafter described).

Preferably said projection is substantially straight but is preferably at an angle to a general longitudinal axis of said shank (preferably said shank is straight).

Preferably any angle of any such substantially straight projection to a substantially straight shank can extend (with respect to a line normal to the general longitudinal axis of said substantially straight shank) from -30° (eg; towards the eyelet or opening end of the shank) to +90° (ie; towards the bight end of the shank). Preferably the fish hook whether integrally formed or formed as a combination of components is of a form generally described by reference to the accompanying drawings. Whilst in preferred forms reference is made to metal (eg; an appropriate steel, etc.) for both the hook and the attachment or the means providing the projection other suitable materials or combinations thereof may be utilised.

In a further aspect the present invention consists in a fishing line having a multiple of fish hooks thereon each adapted to be selective for a particular fish size, such fish hooks each being provided with a substantially similar projection of the kind previously defined.

In yet a further aspect the present invention consists in a method of selectively fishing for fish of a species within a particular size range (eg; above a minimum size) which comprises the operative use of a fish hook with an integral or attachment provided projection of the kind previously defined and thereafter (optionally) returning unwanted fish from such hooks to the sea or water.

In still a further aspect the present invention consists in a fish hook as previously defined selective substantially for a fish of over 30 cm fish size when of a form substantially as hereinafter depicted with reference to Figure 1 irrespective of whether or not the projection is integrally attached or (as shown in the drawings) provided as an attachment.

In still a further aspect the present invention consists in a fish hook as previously defined selective substantially for a fish of over 42 cm fish size when of a form substantially as hereinafter depicted with reference to Figure 2 irrespective of whether or not the projection is integrally attached or (as shown in the drawings) provided as an attachment.

In still a further aspect the present invention consists in a fish hook as previously defined selective substantially for a fish of over 34 cm fish size when of a form substantially as hereinafter depicted with reference to Figure 3 irrespective of whether or not the projection is integrally attached or (as shown in the drawings) provided as an attachment.

To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims. The disclosures and the descriptions herein are purely illustrative and are not intended to be in any sense limiting.

The invention consists in the foregoing and also envisages constructions of which the following gives examples. BRIEF DESCRIPTION OF DRAWINGS Preferred forms of the present invention will now be described with reference to the accompanying figures in which;

Figure 1 shows a conventional fishing hook having as an attachment thereto a 40 mm long protuberance which (as detailed hereinafter with reference to Trial 6) provides selectivity above 30 cm fish size, Figure 2 shows a similar hook to that of Figure 1 again with a 40 mm protuberance but this time extending at a different angle and from a different position, such a hook (as used in Trials 1, 2 and 3 discussed hereafter) having selectivity above 42 cm fish size- Figure 3 is a similar view to that of Figures 1 and 2 but showing a still further variant (as referred to in Trials 4 and 5 hereinafter) having selectivity above 34 cm fish size, each of the arrangements shown in Figures 1 through 3 showing a retrofit device to a normal commercial fish hook but the same result being achievable in any appropriate material whether as in a integral component or as (in Figures 1 through 3) a retrofit, Figure 4 shows graphs showing data for Trials 4 and 5 using squid bait and a 20 mm wire appendage as shown in Figure 3,

Figure 5 is also two graphs showing data for Trials 4 and 5 using squid bait and a 20 mm wire appendage as depicted in Figure 3,

Figure 6 also for the same trials as Figures 4 and 5 show still other graphs of the results,

Figures 7, 8 and 9 are similar graphs for a different trial to those described with reference to Figures 4 through 6,

Figures 10 to 12 show still further graphs of the kind previously depicted in relation to still different trials, this time using a 40 mm wire appendage, Figures 10 through 12 showing the outcome of data for trials 1, 2 and 3 whilst Figures 4, 5 and 6 show the data for the outcome of trials 4 and 5. DETAILED DESCRIPTION

The preferred form of the present invention provides for an extension or appendage the distal end of which is sharp. The length of the extension or appendage is selected so as to limit the number of fish of target species which are caught of less than a target or selected size.

The present invention arises from the results of at least 7 comparative hook trials undertaken where normal hooks (control) have been run against hooks fitted with a variety of selective appendages.

In some trials the modified hooks of different types were run intermittently with the normal hooks. In the remaining trials were run with intermittent groups of 29 modified hooks against groups of 29 normal hooks. (Each trace tray held 29 hooks per side). Each line had 116 hooks fitted.

Depending on weather and crew experience, either 3 or 4 longlines were set per day. The trials were conducted under a special permit which allowed for a total catch of 500 snapper. This level of catch has been reached.

Several previous experimental trials were undertaken where hooks with appendages of one type were run against hooks with other types of appendages or with chemically sharpened appendage hooks against normally sharpened hooks with appendages. All hooks used were 16R size longline hooks of the Tainawa pattern. It has been a consistent feature of the appendage selection trials that the sharpness of the hook used has an effect on the Catch Per Unit Effort (CPUE), ie sharper hooks had a higher CPUE on all size classes.

Because of the observed importance in the sharpness of the hooks, all hooks were replaced after every two trips in the most recent trials. The length of the appendage was found to be critical to the selectivity of different size classes of fish. A shorter appendage resulted in less small fish and a shifting of the entire catch profile to the right as shown in Figure 4.

The fitting of the appendage is achieved by utilising the snood knot already used by commercial fishers. It is simply held in place during tying the snood to the hook and is securely held in place by the knot. It takes around 3 seconds longer than normal to tie the snood to a hook with an appendage. Baiting and setting speeds appear to be unaffected.

Three different devices as shown in Figures 1 to 3 were trialed against hooks that had no device fitted. In each of the trials the hooks with the device were set intermittently with exactly the same hooks without the device. Exactly the same number of each hook type were run and size and type of bait were consistent between the hooks fitted with the device and the hooks without the device on each trial.

In trials 1, 2 and 3 a 40 mm device was fitted half way down the shank of the hook on the opposite side from the bight and angled down and away from the hook at 45 degrees.

This design of the device resulted in a dramatic reduction in the number of fish less than 42 cm being caught while the weight of the landed catch of 42 cm plus fish were the same on both hook types. Four of the five largest fish were taken on hooks fitted with the device. On the hooks without the device 230 fish under 42 cm were caught on which 58 were gut or gill hooked. Hooks fitted with the device caught 153 fish under 42 cm, none of which were gut or gill hooked.

In trials 4 & 5 the device was shortened to 20 mm. This altered the selectivity to 34 cm plus fish. The weight of fish above 34 cm was the same on both hook types.

The four largest fish were all taken on hooks fitted with the device. On hooks without device 345 fish under 34 cm were taken of which 161 were gut or gill hooked. Hooks fitted with the device only caught 172 fish under 34 cm, two of which were gut hooked. In trial 6 a 40 mm device was attached to the back of the hook positioned at approximately right angles to the shank on the opposite side of the bight. The device left the shank at the bottom on the eye of the hook. The total weight of fish above 30 cm (the optimum size at which snapper should be harvested) was significantly greater on the hooks fitted with the device.

The hooks without the device cause 103 fish under 30 cm of which 57 were gut hooked. Hooks with the device fitted caught 63 fish under 30 cm of which none were gut hooked. 12 of the 16 largest fish taken were caught on hooks fitted with the device. During the trials fishing gear was set at a variety of depths from 15 to 40 metres.

Areas fished were Tiri, northern face, 20 to 40 metres; between Tiri and Kawau, worm bed, 40 metres; between Tiri and Whangaparaoa, north of cable of area, 30 metres; out from Waiwere, 15 to 20 metres; south of Kawau, 35 to 40 metres; and outside Motoketekete Island, 25 to 35 metres.

Baits used were normal sized Octopus, normal sized Blue Mackeral, small and normal sized squid strip baits and large baits of half baby squid. Normal baits were approximately 20mm x 40mm. Baits were hooked through once at one end with the point and barb clear of the bait. Only one bait type was used per day.

Gut hooking rates varied. The least gut hooking occurred in conjunction with the lowest catch rates and small baits which may indicate that gut hooking is a factor offish abundance and competitive feeding behaviour. The overall gut hook rates on the normal hooks were 29.7 per cent. Gut hooking did not appear to be related to bait size.

The highest gut hooking rates occurred in fish less than 31 cm and then reduced with increasing fish sizes. No fish over 40 cm were gut hooked.

The number of legal sized fish taken by the normal hooks is still greater, but the appendage appears to deter small fish from taking the bait, hence the bait is left longer in the water and more larger fish are able to be caught. While the modified hooks caught 16 per cent fewer fish than the normal hooks the weight of legal sized fish taken by each hook type were virtually the same.

The above results clearly indicate that the device affects the selectivity of the fish hook it is attached to by reducing the number of smaller fish caught and increasing the number of larger fish caught when compared directly to the performance of the same hooks without the device being fitted.

It is also demonstrated that altering the configuration of the device allows said selectivity to be adjusted so as to minimize the capture of undersized fish under a range of minimum legal size scenarios. In the results reported the NZ fish known as snapper were the target species and only snapper are represented in the results. Also only one type and size of hook was used.

The intended usefulness of the device is not limited to snapper or the hook size or type or in fact the dimensions mentioned, neither is the devices' application limited to baited hooks. It will clearly be as effective on hooks with lures, jigs, poppers or soft artificial or sponge type baits as well. Fish eat a variety of foods and species that are omnivorous or carnivorous have to contend with a variety of choking hazards and potential digestive catastrophes if their often spiky or prickly prey is swallowed incorrectly.

While smell and visual clues may rouse a fishes interest in a potential food source all fish rotate prey thoroughly in their mouth parts prior to swallowing, all fish that are eaten are always swallowed head first to prevent the spines being raised and causing serious damage to the internal parts of the predator fish or the backward facing backbone causing damage as the flesh is digested.

Other sharp fish foods such as sea urchins, crabs and shellfish are chewed and constantly rotated, respectively expelled and picked up again to similarly align the food item to pass easily into and through the fishes digestive tract. Obviously visual and olfactory clues are insufficient to explain this behaviour in fish. Additional sensory areas inside the fishes mouth parts and internal gill area must sense when a prey item can be safely swallowed. The device being relatively sharp and prickly deters many small fish completely because the device becomes wedged in the front of the mouth parts immediately the bait enters the mouth. These fish either spit the bait out completely and consider it inedible or too dangerous, in which case the baited hook remains fishing. Alternatively, the fish is hooked in the mouth parts while trying to eject the bait. Larger fish do not become aware of the device until the hook is further into the mouth parts as there is sufficient room inside the closed mouth that a device does not become wedged and scare or spook the fish. However, larger fish are aware of the device (this is attested by the fact that even very large fish very seldom get gut or gill hooked on the hooks fitted with the device) but are content to work at trying to align the device so it can swallow the bait. As this is nearly impossible eventually the fish will be caught in the mouth parts while trying to chew the device off or align it, possibly even repetitively spitting it out and trying again.

If the results achieved in the trials can be duplicated in the commercial fleet several benefits to the stock will occur. These benefits are derived at a SNA1 Commercial longline catch of 2,500 tonnes per annum. (An effective size limit means all snapper above that size limit caught are landed regardless of condition). At an effective 25 cm size limit 335 less snapper would be killed per tonne of landed catch. This would save 837,500 snapper per year.

At an effective size limit of 27 cm, 441 less snapper would be killed per tonne of landed catch. This would save 1,077,500 snapper per year. At an effective size limit of 30 cm, 752 less snapper would be killed per tonne of landed catch, saving 1,880,000 snapper per year.

Wastage of scavenged snapper above any of the size limits would also be reduced as this mainly occurs in gut hooked fish that are on the sea bed in a dead or dying state. Normal hooks gut hooked 35 kg out of 140 kg of catch, modified hooks only gut hooked 2 kg out of 140 kg of catch.

High grading of dead snapper above the Minimum Limit Size (MLS) would be reduced by over 90 per cent from current levels.

Commercial CPUE and economic returns are higher on the modified hooks under every scenario examined.

Claims

CLAIMS:

1. A fish hook of a kind having a hooking portion (or "bight") [which may optionally have one or more barbs or other retaining means thereon], said bight having a distal sharp region, and a shank wherein either integrally formed from said shank or provided as an attachment there is a sharp ended projection of finite distance, the projection extending from the shank away from the distal sharp region of said bight.

2. A fish hook as claimed in claim 1 wherein said projection extends away from shank in the general plane of the hook.

3. A fish hook as claimed in Claim 1 or 2 wherein said finite distance is chosen with a view to selectivity of fish sizes, for example, a distance of from say 15mm to 60mm.

4. A fish hook as claimed in Claim 3 wherein said finite distance is from 20mm to 40mm.

5. A fish hook as claimed in any one of Claims 1 to 4 wherein said projection projects from said shank from between the ends thereof whilst in other forms said projection projects away from said shank at or adjacent the snood or line attachment aperture, eyelet or other means thereof.

6. A fish hook as claimed in any one of Claims 1 to 5 wherein said projection is in the form of a wire or the like member which, if being provided as an attachment to a fish hook, includes means which passes through the eyelet or opening of the fish hook for line or snood attachment and thereafter clamps to said shank.

7. A fish hook as claimed in any one of claims 1 to 6 wherein said projection is substantially straight but is preferably at an angle to a general longitudinal axis of said shank (preferably said shank is straight).

8. A fish hook as claimed in any one of claims 1 to 7 wherein said shank is straight.

9. A fish hook as claimed in Claim 7 or 8 wherein any angle of such substantially straight projection to substantially straight shank can extend (with respect to a line normal to the general longitudinal axis of said substantially straight shank) from -30┬░ (ie: towards the eyelet or opening end of the shank) to +90┬░ (ie; towards the bight end of the shank).

10. A fish hook whether integrally formed or formed as a combination of components is of a form generally described by reference to the accompanying drawings.

11. A fishing line having a multiple of fish hooks thereon each adapted to be selective for a particular fish size, such fish hooks each being provided with a substantially similar projection of the kind substantially as claimed in any one of Claims 1 to 10.

12. A method of selectively fishing for fish of a species within a particular size range which comprises the operative use of a fish hook with an integral or attachment provided projection of the kind as claimed in any one of claims 1 to 10 and thereafter (optionally) returning unwanted fish from such hooks to the sea or water.

13. A fish hook as previously defined selective substantially for a fish of above 30 cm fish size when of a form substantially as hereinafter depicted with reference to Figure 1 irrespective of whether or not the projection is integrally attached or (substantially as shown in the drawings) provided as an attachment.

14. A fish hook as previously defined selective substantially for a fish of above 42 cm fish size when of a form substantially as hereinafter depicted with reference to Figure 2 irrespective of whether or not the projection is integrally attached or (substantially as shown in the drawings) provided as an attachment.