SPC/ 20/WP.33 27 July 1988

ORIGINAL: ENGLISH

SOUTH PACIFIC COMMISSION

TWENTIETH REGIONAL TECHNICAL MEETING ON FISHERIES (Noumea, New Caledonia, 1 - 5 August 1988)

PROGRESS REPORT ON SPC GEAR DEVELOPMENT PROJECT

Paper presented by the Secretariat

INTRODUCTION

Background

1. Since September 1986, the SPC Gear Development Project (GDP), an activity of the Deep Sea Fisheries Development Project, has been based in Vava'u, Kingdom of Tonga. Project personnel consisted of one SPC Master and a single local trainee/ crewman employed by the Commission. Tonga Fisheries Division was to have attached extension officers to the Project as trainee/ counterparts but due to staff shortages this only happened occasionally. SPC Project personnel were assisted in FAD construction and deployment by Tonga Fisheries Division staff and local fishermen. Tonga's main contribution to the Project consisted of FAD materials, boats, a secure storeroom, and strong logistical and moral support. The FAO/UNDP Regional Support Programme made major contributions of gear and FAD materials. In addition to staff, SPC provided some FAD hardware, running costs for the Project boats, and fishing gear.

Objectives

2. The main objectives of the Project were:

- to adapt and improve techniques for catching bait, i.e. the small fish suitable for use, usually whole and sometimes alive, on handlines and vertical longlines set for tuna (e.g. scads such as Decapterus spp and Selar spp) and on surface and sub­ surface lines (e.g. flying fish, Exocoetus and Cypselurus spp);

- to experiment with existing techniques of deep trolling, particularly those used by fishermen in the north-east Pacific, and by sports fishermen in the USA, and adapt them to the capture of deep-swimming tunas, especially those found in association with FADs.

3. Secondary objectives were:

- to carry out deep bottom fishing trials in depths greater than 400m, and (in all depth ranges) on the windward sides of established fishing areas, where conventional fishing using wooden handreels or handlines is difficult or impossible;

- to provide advice to the Government of Tonga as required on aspects of local fisheries development.

892/38 SPC/Fisheries 20/WP.33 Page 2

Activities

4. In order to meet these objectives, the following activities were carried out:

Construction, deployment, maintenance and monitoring of fish aggregation devices (FADs);

Experimentation with a variety of bait catching methods including , trolling, the use of two different types of , and scoop-netting;

Surface, sub-surface and deep-trolling in inshore and open waters and around FADs;

Experimental deep-bottom fishing using bottom longlines and

5. In addition, vessel maintenance, record keeping and other routine activities occupied substantial parts of the Projects time.

6. The purpose of this progress report is to provide an update of the Projects more important activities since it commenced operations. The report is necessarily incomplete as Project activities will not conclude until later in the year. A more detailed terminal report will be prepared at that time.

Project vessel and facilities

7. The Tonga Government made available for the Projects full-time use the 8m fibreglass Yamaha Vete. The vessel was equipped with a 24hp Yanmar ME series dry-exhaust inboard diesel engine, and had a small cabin where electronic and fishing gear could be stored and kept dry while at sea, but which was inadequate for crew accommodation. The vessel had two integral holds in the after deck and three forward, all of which were watertight and one of which was insulated for ice storage. Deck equipment included a Japanese pressure-roller type line hauler, and Koden dry paper echo-sounder with 50 kHz transducer. The Master Fisherman added Koden 8812P chromascope with a dual 28/200 kHz transducer. All the transducers were mounted on lengths of galvanised pipe which could be attached to brackets fixed on the side of the boat. This allowed easy removal of the transducers and avoided major structural work on the hull to mount them. However, the sounders did not function as effectively as they would have if they had been mounted through the hull. In addition, the pipe mounts caused obstructions to some of the fishing operations, as well as being hazardous for the crew.

8. The Project also made occasional use of another fishing boat belonging to Tonga Fisheries Division. This was an open 9.6m Yamaha skiff with self-draining deck and powered by a 55hp Evinrude outboard motor, which was used for hoop-net trials.

9. Most on-shore gear preparation, construction and maintenance was carried out either on the fisheries compound by the main wharf in Vava'u, or in a small gear workshop and office under the Master Fisherman's home. FAD CONSTRUCTION AND DEPLOYMENT

10. In order to accomplish its objectives the Projects first priority was the construction and deployment of FADs. Seven FADs were deployed between September 1986 and April 1988, six for project use and one on behalf of Vava'u Fisheries Division. One of the six deployed for the Project, which was lightly constructed and deployed in a depth of 80m, was lost in heavy weather in December 1986. The FAD deployed in 60m for Fisheries Division as part of a seaweed culture experiment sunk as a result of heavy weed and shell growth. The other five FADs are still in place, two in deep water (780 - 820m) and three in shallow water (30 - 80m). SPC/Fisheries 20/WP.33 Page 3

Table 1: Summary information on FAD deployments

Number Depth Conditions Deployment date Total time 11. in place months

FAD1 36 Inshore sheltered waters Sept 86 23 FAD 2 82 Inshore sheltered waters Jan 88 6 FAD 3 800 Lee side of main island Nov 1986 20 FAD 4 80 Lee side of main island Nov 1986-Jan 1987 2 Redeployed April 1987 16 FAD 5 820 Open sea, strong current April 1988 4

12. All FADs were regularly inspected and maintenance work carried out when signs of wear or imminent breakage became apparent in the raft components or accessible parts of the upper mooring line. As a result, considerable experience in the design and construction of FADs has been accumulated. It is not possible to present this in detail here but this information will be documented in the Project's terminal report.

TROLL BAIT FISHING

13. At the present time in Tonga, most large-sized fully-rigged trolling lures commonly used for larger rapacious pelagic fish species such as wahoo, dogtooth tuna, yellowfin tuna, barracuda and trevally, sell for T$ 15.00 to T$ 25.00. This type of lure can be destroyed by a single fish strike and their use can be a very expensive method of fishing. There are several fish species that are very effective when rigged as trolling baits, in particular shark mackerel and flying fish. Methods of catching, rigging and trolling these species have been stressed during the Projects stay in Vava'u. Capture methods experimented with were light lure trolling (for shark mackerel and barracuda) and scoop netting (for flying fish). This latter was probably the most cost effective means of acquiring good trolling bait.

Scoop-netting

14. Although the technique of scoop-netting for flying-fish by light at night is well known in some areas of the Pacific, it is not practised in Tonga at the present time. Flying fish are excellent trolling baits, freeze well and stay firm on thawing, and in times of shortage can be used on several consecutive days. One 48 kg yellowfin tuna was caught in Vava'u using a flying fish that had been trolled for several hours on each of the three preceding days.

15. A box-type reflector housing two 200W bayonet-mount household light bulbs was built and mounted on a 2.5m removable pole on the front of the Vete. The bulbs were powered by the Project's portable Yamaha ET900 12/240v generator, which has a fuel consumption of about 51/ 8 hours.

1 6. The frame of the scoop net was made from a 2m length of 10mm diameter aluminium pipe, bent into a triangle. The tubing was shaped by first filling the pipe with damp sand, and then using a plumbers pipe bender to obtain the desired shape. After shaping the frame was lashed onto a 3m handle made by planing down a length of 50mm x 50mm length of pine timber. The handle was made as smooth and light as possible. The netting, which was of 19mm mesh multifilament nylon, was then tied on to form a bag.

17. On the Vete, scoop-netting required two people, one to run the boat and the other to scoop fish from the bow. All netting was carried out during moonless nights in fairly sheltered waters on the western side of Vava'u. Flying fish were generally easier to scoop on dark nights 3-4 days on either side of the new moon. SPC/Fisheries 20/WP.33 Page 4

18. Scoop-netting was carried out on 7 different occasions, producing a total catch of 594 flying fish, at an average rate of about 15 fish per fishing hour. Flying fish currently sell in Vava'u for T$ 1.00/fish.

Light lure trolling

1 9. The main gear for this fishing method was essentially the same as that used for sub­ surface trolling (see paras 31 - 33), i.e. two Alvey reels fitted with 50m of 1.2mm 7x7 strand stainless steel cable. For light trolling, the cable terminated in a 8-10mm pearl head with squid skirt tied on, and rigged on a 2-4m length of 20-30kg test monofilament . The main target species for this type of trolling were shark mackerel (Grammatocynus bilineatus), little tuna (Euthynnus affinis) and small barracuda (Sphyraena sp). The main shark mackerel fishing areas were the banks to the south of the Vava'u group. Shark mackerel schools were usually found on the up-current edges of shallow reef patches and around the mouths of passages or channels through the sunken barrier reef. As there were usually toothy fish such as barracuda, dogtooth tuna and Spanish mackerel around the shallow patches, lures were usually rigged on a 1m length of 25-30kg single strand trace wire attached to the main cable by a length of 20-30kg nylon monofilament when trolling in these areas.

20. After a few trips to gain experience, shark mackerel schools were easy to recognise on the chromascope as they seemed to have a much more vertical formation than other school fish. On many occasions, birds were noted working a small area on the up-current edge of a shoal or reef patch. At these times, passing over the area with the chromascope on would reveal a clear picture of a fish school reaching from near the surface to a depth of 15-30m in a total water depth of 40m.

21. Bait trolling was carried out on 17 different occasions producing a catch rate of 2.7kg/ line/ fishing hour, or 1.3 fish/ line/ fishing hour. The average weight of the fish caught was 2.1kg, (which was higher than might be expected because of dogtooth tuna that were occasionally taken by this method). After Project staff became familiar with the area, it was possible to obtain bait any time it was needed. Bait trolling could also be carried out when the sea was too rough for open-water or deep sea fishing.

VERTICAL LONGLINE/ TUNA HANDLINE BAIT FISHING

Jigging

22. Jigging was carried out around FADs using Japanese '' jig sets on light spin casting gear. The type used are stocked in several different shops in Tonga and sell for T$ 1.95 to T$ 3.95, depending on the size, number and make-up of individual jigs in the set. The use of light spinning gear was found to be far more effective than handlining due to the flexibility and leverage of the rod. Jigging was effective around the 36m FAD for a limited time period shortly after sunrise during the cooler months of the year. Scad, juvenile golden trevally and juvenile rainbow runner could be caught at any time during daylight around the 82m inshore FAD, but were easier to catch in the early morning and late afternoon. Catch rates around the FAD averaged over 70 fish per jigging hour. Experimentation showed that up to a dozen scad could be transported as live bait for up to 12 hours in the boats small icebox filled with fresh sea-water. SPC/Fisheries 20/WP.33 Page 5

Lift-netting - 'Kopelu' net

23. During February 1988 a joint 'kopelu' net fishing experiment was carried out with the FAO/UNDP South Pacific Regional Fishery Support Programme. Personnel involved were FAO Fisheries Development Adviser, Gear Development Project personnel, and Tonga Fisheries Division staff. A full description of the fishing technique has been published in the FAO/UNDP Programme report 'Hawaiian Hoop Net Fishing for Decapterus around Niue' and the results of the Vava'u fishing trials have also been written up by the FAO/UNDP Programme. Subsequent to the trials, a Fisheries Officer from the Cook Islands spent a month in Vava'u to receive training from the Master Fisherman in the use of the net, hence additional netting demonstrations were carried out at this time.

24. As the Vete did not have the clear deck arrangement required for this type of fishing, arrangements were made to use a 7.6m Yamaha skiff belonging to the Fisheries Division. The skiff was powered by an Evinrude 55hp outboard motor and its open self-draining deck layout made it an ideal platform for this type of fishing.

25. After two days spent in assembling the net, which was imported from Hawaii, and experimenting with its use, thirteen days were spent areas where bait schools might be expected to occur. Although the Master Fisherman had previously observed schools of scad ('kopelu') along the lee shore at roughly the same time period the previous year, no schools were located This was in despite of a progressive chumming of the 20-40m depth zone along the whole of the iee shore. In addition, chumming was carried out over a substantial area of inshore waters, again with negative results.

26. As no Decapterus schools were located, practice runs at setting the net.chumming, and hauling the net were made on schools of Caesio sp, which were attracted to the chum but which could not be manoeuvred into the net for capture like Decapterus . Even though no Decapterus were captured during these trials, the method appears to have potential in areas where this genus is plentiful.

Lift-netting - hoop net

27. In early 1987 an approximately 3m diameter hoop net was assembled using using 18mm mesh nylon monofilament netting slung as a bag on a circular frame made from reinforced PVC pipe. The net was constructed as a lift-net to be used in conjunction with underwater lights for bait capture at night.

28. For fishing, two 250W light bulbs housed in waterproof reflectors and powered by the Projects small generator were hung over the side of the boat to attract bait species on dark nights. After several hours of running the generator the amount of bait present and an indication of the individual fish size could be deduced from observations using the boats echo sounder.

29. When it was judged that there was enough bait present, the lights would be dimmed, causing the fish to bunch more tightly together around the light source. This resulted in the bait congregating near the surface and over the top of the net. The net was then hand-hauled up from under the school, using an arrangement of blocks and tackle attached to heavy booms mounted on the boat for this purpose.

30. Catches and fishing results in general were moderately encouraging. However, the cabin and superstructure amidships, narrow walkway, and tendency to roll heavily when hauling the net all combined to make handling the net on the Vete difficult and dangerous. Further trials of this method were therefore discontinued pending the availability of a more suitable vessel. SPC/Fisheries 20/WP.33 Page 6

TROLLING

Sub-surface trolling

31. Sub-surface trolling was usually carried out to target on reef-associated species. The basic method has been described in SPC/Fisheries 15/WP 3 and in SPC Handbook # 28, 'Trolling Techniques for Pacific Island Fishermen'.

32. Distance of the reef offshore and surrounding water depth greatly influenced the species composition of the catch. Rigged baits, usually flying fish, shark mackerel or scad were trolled from two Alvey reels mounted on the stern of the Vete. The Alveys were of two different sized models, a 'Reef Master' and a 'Reef King'. Rigged baits were trolled at 4-6 knots behind 50m of 1.2mm diameter stainless steel cable, the cable being backed by 300m of 50kg test "Super Toto' braided line on the Reef King.

33. This type of trolling around the Vava'u area was considerably more productive than using lures. Although the most productive trolling time was usually the 2-3 hour period around sunrise, this method produced fish at all hours of the day. The majority of fish caught were high quality species, mostly dogtooth tuna and wahoo. The overall catch rate was 4.7gk/ line-hour, with "prime time" catch rates more than double this figure.

Deep trolling

34. There are several different versions of deep water or downrigger trolling in use in a number of well established fisheries, such as the commercial troll fishery for salmon off the west coast of North America and Canada. An adaptation of the basic techniques was seen as a possible means of catching tuna around FADs after the usual "early morning bite" had stopped and fish were deeper. The Projects approach while in Vava'u was to use the chromascope and echo-sounder in combination to locate fish, monitor the deployment of the gear, and to observe fish reactions when the gear was presented.

35. Results from SPC deep trolling trials around a FAD in Fiji in 1985 using typical west coast commercial salmon trolling gear seemed to indicate that this configuration was not effective for the fish being targetted, mainly large yellowfin. The main downrigger wire was of relatively large diameter and required a heavy weight to keep it down, even at very low speeds (1-2 knots). The snap clips commonly used for attaching the lures to the mainline were not strong enough to take the initial strike of a large tuna, and the swivels frequently broke. The working area on most boats used by artisanal fishermen in the region is insufficient to allow handling of the heavy multi- gear safely, and most boats are not equipped with mechanical gear to haul the heavy downrigger weights.

36. In Vava'u, deep trolling trials were to be carried out around the 800m FAD deployed on the lee side of the island. Unfortunately, the FAD has never consistently held tuna, although there are usually small fish present, as well as rainbow runner, dolphin fish and occasionally wahoo. Due to the lack of deeper swimming tuna, the amount of deep trolling attempted was limited.

37. Nevertheless, a deep-trolling system was developed which is fairly easy to use and has shown promising results (figure 1). A smaller version of a FAO-style wooden handreel was constructed, since the smaller diameter of the reel made the hauling a heavy downrigger weight easier. As with the version of the reel used for vertical longlining, a Kolstrand 13cm diameter nylon pulley replaced the standard insulator on the reel arm. The reel was mounted forward of the cabin and fitted with 100m of 75kg test single strand stainless steel wire, onto the end of which was clipped a 12kg sinker made from a lead-filled length of 50mm diameter galvanised steel pipe. SPC/Fisheries 20/WP.33 Page 7

Sounder box V^ Handreel Alvey reel

Stainless steel wire (75kg test, small diameter)

>£3>

Heavy Super Trolling sinker Swivel Toto line (12kg lead-filled shaped 50mm pipe)

Figure 1: Deep-trolling arrangement

38. In conjunction with this system, a rigged bait or action lure was trolled from an Alvey reel mounted on the stern of the boat. After locating a promising area using the echo sounder, the rigged bait was attached to the downrigger weight using a break-away system. This consisted of a loop of 25kg test monofilament, attached to the swivel between the rigged bait leader and the mainline, and connected to the sinker by a length of heavy 'Super toto' braided line. After attaching the bait to the downrigger in this way, the drag on the Alvey reel was slackened off, and the sinker lowered to the desired depth. As each turn of the handreel was 1m the exact trolling depth could be set by counting turns of the reel. Depth can also be determined by watching the descent of the sinker and attached bait on the echo- sounder. After reaching the desired depth, the drag Alvey reel was tightened to the proper setting and the rig trolled at a speed of 1.5 to 3 knots.

39. When a strike occurred, the 25kg breakaway loop snapped, leaving the fish attached only to the Alvey reel. The downrigger weight was quickly hauled to the surface and lifted inboard, while the fish was played and landed on the Alvey.

40. Although this fishing method was used on only a limited number of trips, the overall catch rate was over 5kg/ line hour, including periods of trolling in a fairly random manner to practice using this gear configuration. When only the promising areas located using the echo-sounder are taken into account, the catch rate was over 19kg/ line hour. The catch consisted mostly of dogtooth tuna. SPC/Fisheries 20/WP.33 Page 8

DEEP BOTTOM FISHING

41. The development of bottom- that would allow the exploitation of deep-bottom fishes in areas that were difficult to fish using conventional handreel or handline techniques was established as a priority activity during the formulation of the SPC Gear Development Project. Areas of sea floor deeper than 400m, and the windward sides of islands and reefs, were identified as potential fishing grounds that might be exploitable if suitable fishing techniques could be developed.

42. In Tonga, however, the deep-bottom fishery is developing rapidly, with the assistance of the Tonga Government. The number of vessels in this fishery increases yearly, and the level of deep-bottom fish exploitation, which is already high, is continuing to climb. A number of coastal areas and seamounts have been heavily fished and no longer yield adequate catches of desired deep-bottom species. Fishermen are being forced to travel further afield to reach good deep-bottom fishing grounds, and there are concerns that the fishery may not be able to sustain even present levels of exploitation in the long term.

43. In view of these concerns, the development of techniques to exploit presently unfishable areas takes on a new significance. It is possible and perhaps likely that these inaccessible fishing areas form a 'reserve' which may help prevent the resource from being driven down by excessive fishing pressure. Until the pace of development of the fishery slackens, or more is learned about the nature of the resource, it may be irresponsible to encourage development of techniques for the exploitation of presently unfishable deep- bottom grounds in Tonga. This concern greatly influenced the approach taken by the Project in pursuing these trials in Vava'u.

Bottom longlines

44. A limited number of bottom longline sets were made in depths of 400m or more, in order to assess the suitability of this method for fishing in depths beyond the range of conventional handreel or techniques.

45. The longlines were rigged using the same basic 30-hook configurations as in previous trials carried out in Fiji (figure 2). Longline sets were made in depths from 450 to 600m, and produced a catch with a species composition very similar to that obtained by deep-bottom handreel fishing in Vava'u. Trials were discontinued once it became apparent that the Vete's deck layout was not amenable to carrying out this type of fishing effectively.

Droplines

46. Droplines were used in an attempt to access windward slopes where normal methods of fishing using a handreel or handline are not possible, because the wind direction prevents the boat from being maintained in a position above the desired fishing depth.

47. To enable deployment of the lines, a snatch block arrangement, made from a Kolstrand 13cm diameter pulley set into wooden plates on each side, was attached to the arm of a FAO-type wooden handreel in place of the usual ceramic insulator used as a line guide. The open top of the pulley allowed the easy removal and replacement of the line.

48. Two droplines were usually fished at a time. For each , a small grapnel made from No.9 galvanised fence wire was lashed onto the bottom end of a 1.5 to 2kg sinker cut from heave steel bar. A ten-hook bottom rig made of Turimoto wire and tuna circle hooks was made up using the same longline knot and eyed traces as used in a standard deep-bottom fishing terminal rig. A float and flag arrangement, as shown in figure 3, were made up and held ready for use as a line marker. SPC/Fisheries 20/WP.33 Page 9

Longline float ,3m PVC pipe flagpole

Net float

4kg rebar sinker 3m x 6mm kuralon

• 400-600m 6mm polypropylene rope

10mm rebar grapnel' 15cm wire snoods attached to 6mm kuralon mainline by shark clip

30 hook bottom longline

Figure 2: Bottom longline arrangement

49. To fish the lines, a likely fishing area was identified by examining the configuration of the sea floor using the chromascope. Using the sounder to actually locate fish in these windward areas was difficult due to the normally rough sea conditions and the steepness of the slope. After baiting the lines and selecting a fishing spot, the rig was lowered as quickly as possible to the bottom while the boat was, as far as possible, held on station using the engine, so as to keep the line straight up and down. When the sinker touched bottom, the line was slacked off a further 6-8 turns of the reel, the reel removed from the upright (the open top of the snatch block allowing the line to be lifted out from the guide), a flagpole/ float combination quickly tied onto the reel so as to prevent it from unwinding any further, and the lot then dropped over the side. The next line was then dropped in the same manner within easy visual range, after which the first line was hauled. SPC/Fisheries 20/WP.33 Page 10

FAO wooden handreel

«3m PVC pipe flagpole

'Jet float

' 4kg rebar sinker 3m x 6mm kuralon

• 135kg test nylon monofilament mainline

10-hookTurimoto wire bottom rig

*^ $sd

•pftxc-'iwm-

Figure 3: Dropline arrangement

50. Hauling was the reverse procedure to shooting. The flagpole/ float combinations enabled easy sighting and recovery of the reels, which were then replaced on the upright reel post and wound up manually. By alternating the two lines, four to six sets could usually be made per hour, depending on catch and sea conditions. Typical soak time for a line would be 15-20 minutes.

51. In the immediate vicinity if Vava'u this fishing method proved relatively inefficient as the bait was rapidly stripped from every hook on the line with only a small number of fish being caught. Bait is normally expensive and difficult to obtain, and fishing methods which are wasteful of bait would not be feasible in many areas.

52. Several hours of standard reel-fishing, using a normal 3-4 hook terminal rig, were carried out on each droplining trip in order to enable a comparison of the effectiveness of the two methods. To do this it was necessary to hold the Vete on station using the boats engine, since it was impossible to fish from an anchored position. Catch rates per reel-hour using standard fishing techniques were more than twice as high as with the droplines, despite the smaller number of hooks used, and bait consumption was considerably less. SPC/Fisheries 20/WP.33 Page 11

53. The method could nevertheless have merit in areas where bait is plentiful and large fish are abundant.

SUMMARY

54. The Gear Development Projects work to date in Tonga has allowed substantial progress to be made in refining a number of locally appropriate small-scale fishing methods for use in the Pacific Islands context. This work is of relevance to a number of Pacific Island countries. A full and detailed reporting will be made when the Project concludes its activities in Tonga, so that complete information on the progress achieved is available. This work will serve as a foundation for forthcoming SPC gear development activities in Kiribati.