SPC/Fisheries21/WP. 30 7 August 1989

ORIGINAL : ENGLISH

SOUTH PACIFIC COMMISSION ,

21ST REGIONAL TECHNICAL MEETING ON (Noumea, New Caledonia, 7-11 August 1989) VERTICAL LONGLININQ -, ;< ' THE CONCEPT,' TRIALS, AND PRESENT STATE OF DEVELOPMENT P ,' . j.'. •...;...•....•''•*••

by

PAUL MEAD SPC MASTERFISHERMAN

DEEP SEA FISHERIES DEVELOPMENT PROJECT GEAR DEVELOPMENT SUB-PROJECT (Vava'u, Tonga) r

660/89

* SPC/Fisheries21/WP. 30 Page 2 Introduction Simply put, a vertical longline consists of a length of mainline suspended near vertical in the water column by a weight at one end and a float at the other, with a number of baited branchlines attached at regular intervals. It permits focussing effort through a band of depth in a single small area, in contrast to more traditional and widespread horizontal longlining which distributes effort over an expanse of ocean.

The notion of a vertical longline surfaced during a country assignment in Yap in 1979. It came about after losing several large fish while outside and along the reef in the area of an extremely steep drop-off. The heavy strikes were confined to that area, and occurred mainly at early morning or late afternoon. The intention of that first vertical longline was to focus fishing effort in these "hbles." The method of those first attempts was to go up-current, lower the longline, and then drift the bait through the holes over a range of depth. '

Since those first trials in Yap, the fishing method and gear configurations have evolved substantially, due to a greater understanding of the geaf and how it responds to a variety of fishing1 and catching situations, and also because much more is known about the behavior of the targetted fish. Vertical longlining moved through a progression of stages and locations before the Gear Development Sub-Project was set up in Vava'u in 1986. It's in Tonga vertical longlining developed to the point it is now - one complementary with local technology, efficiently gets lots of gear in the water, and is generally affordable for local economies. This presentation will briefly track the history and stages of vertical longlining and test fishing trials, list the pertinent findings along the way that helped direct its development, and then focus on present technology and operations of recent work in Tonga.

History Yap (1979). This was the first attempts at vertical longlining, and as mentioned above, the idea was to fish more hooks in holes along the reef where large tunas might dwell. This first time only 1 vertical longline was fished, and the gear was set after dark. A parachute was deployed as a sea anchor to slow the boat's drift through the target area. The longline was 8 mm kuralon mainline with 20 - No.10/0 Sampo swivels spliced in (for branchline attachments) at 8 fathom intervals. Branchlines consisted of a locking snap swivel fastened to a 3 fathom length of 250 lb. test monofilament line that terminated in a No.5 Mustad tuna . If fish struck while the line was being deployed they were fought to the surface and hauled onboard. The first complete haul yielded 4 sharks and 2 dogtooth tuna. Fishing was curtailed at 4 am, and the night's catch was 12 sharks, 2 dogtooth tuna, and 1 large barracuda. Nlue (1982). After that single night of effort in Yap, vertical longlining wasn't tried again until 1982 in Nuie. There vertical longlining was associated with fish aggregating devices (FADs). On first trials fresh flying fish were used as bait, and the longline was set on a FAD after dark and soaked all night. An early morning check revealed no catch, so the line was left to soak through the day, until 4:30 that afternoon. The day set only produced 1 large blue shark. It was decided to postpone further trials until a better bait was available.

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In the meantime the gear was modified. Fisheries Division had a large supply of shark clips, the swivels used,ta.attach the snoods, or branchlines, to the mainline were replaced with shark clips. Instead of clipping thesnood through the lower eye of the swivel, branchlines were snapped directly onto the jnainline just above the splice that joined each swivel to the mainline. ^ • \- ^ Sometime after the gear was modified, large schools of Decapterus were noticed gathered around one of the FADs. Light handlines and a were used to catch enough for use as bait and trials, were, started up again-i The masterfisherman and one other crew, in a 12* aluminium boat, made an early morning run to the FAD, tied off, and set the longline. After the morning's bite finished*,th©catch totaled 5 yellowfin (11 kgs each) and 3 dolphin fish (6 kg average). None of the ifish was caught deeper than 90 fathoms.

Another gear innovation was experimented with: mainline without swivels was tried, Branchline positions were marked, with cord. The idea was abandoned after losing several large fish. Hooked fish wrapped the snood around and around the mainline and then got off. f Cook Islands (1983). In Rarotonga in 1983 local fishermen had already devised their own method of "vertical longlining" around FADs. Their gear usually consisted of a single hook dropped from a.single,fjpat and fished, at depths between 30 and 60 fathoms. Law banned boats from tieing up to FAD*>sq fiahermeamotored 3 r40Q meters uprcurrent, dropped their line, and drifted past. Lines were hauled about 3-400 meters from the FAD on the down-current side.

The Cook Islands was the first spot that two vertical longlines were fished simultaneously, tethered together with;a piece .of floating line. Difficulties with obtaining bait, exceptionally cool winter temperatures, and an El Nino, all combined to confound trial attempts and disrupt the regular seasonal appearance of tunas. Although a new gear innovation arose, few fishing trials were executed. Table 1. Results from vertical longlining test fishing around a FAD in Niue Month No. of Trips Catch .... ~ ~~ 12 yellowfin r Nov 5 3 albacore 6 dolphinfish •. *. 17 yellowfin ... Dec 6 6 albacore , 17 yellowfin Jan 7 3 albacore 1 bigeye 447 yellowfiyellow! n Feb 5 2 albacoralbacoi e 3 bigeye SPC/Fisheries21/WP. 30 Page 4

Fyi (1984). A much more determined approach to developing vertical longlinirig took place during &e Gear Development Project's attachment to Fiji. A Fiji 28 "fo6ter"was the fishing {ttatformyattd several'trip* to a FAD east of Bequa Island with the kuralon longhne prbthiced seVeral large yellowfin and albacore. Even so, the gear was bulky, and careful handling of the line was required because of the limited space onboard the 28 foot vessel. Several points emerged during early operations: ; ; --< •>;. • !v- -?rM'«--<••

|ls,.. ,;, • ,, < •. : /-.-,• •' •>' • •• ..,-•.;•••••,.•. •••- -• • •••-,; > ••'•'**•>• vl« !•'"«:'• .1. Wire snoods were ineffective aftd were more difficult to handle compared to hyloh; s .;'.; 2. A single species of shark was dominant around FADS, but it could be depleted with several days of intense fishing. If the FAD was not fished for 2-3 weeks the process had to be repeated;

-•••'. 3. Tuna hook-ups increased if bait was hooked with the Japanese or Cook Island method instead of hooking through the eyes; -; i; hon; : < r

4. No.3 tuna circle hooks weren't strong enough to hold big fish. Forced to switch to #48 !.••••••, r. • BKN, and even some big fish straightened that size; •''•'" I' -I • O i /•':• > 5. Steady heavy surges of big tuna could undo or break the improved cinch knot. The * palomar knot was more dependable, although more difficult to tie in heavy nylon;': 1 ;. :••..• • >•••••• ;- i-,->!ii.L!? "••;• •'•• 6. If longlines were set after dark, squids stripped the baits in less than an hour;

!...•.••-•! •,- >'!••-...•' , , '. •• • ' ' "••:"'. '.''' 8. After sunrise hookups of most tuna species occurred in water deeper than 30-40 fathftms; 9. Birds working around FADs almost always indicated that fish could be caught; -.;..,,, • . .. .-•..- ••••• •-• •: - '!• ••• U .? ••>"<'; I" 10. A large bait, such as a 1-3 kg skipjack or rainbow runner worked good as a bottom bait; 11. Light line (150 lb test) and smaller hooks (No. 5 Mustad tuna circle hooks) worked good from the surface to 70 fathoms during daylight hours; particularly for dolphinfish and rainbow runner; ,|f1

Several gear innovations were experimented with. The mainline was varied between braided nylon, Super Toto, and nylon monofilament. These alternatives were considered because kuralow mainline was particularly bulky. All three of the lines tested occupied much less deck space than the kuralon, but each was also difficult to haul by hand* A Sarnoan handreel was modified to get around the problem. The only modification required was to replace the terminaF insulator on the lever arm with a 6" nylon pulley to permit the swivels to pas* through. Every reel was capable of storing a single vertical mainline drop. Several drops occupied much less space than the same lengths of kuralon, and the reels were much easier; to load, unload, and store. Additionally, since small diameter line is less affected by current it hangs more near vertical inthe water column1 and also only requires a small sinker. Space saving organisation of snoods was also implemented. Snoods were stored on plastic handcaster spools. It was quickly discovered after trying to land a large 1

SPC/Fisheries21/WP. 30 Page 5

bigeye th^ 50-100 fathoms of backing was necessary on the reels because the fish would sound rapidly once hauling commenced. , Over the cpwrse of several.country assignments it was .shown that vertical longlining worked, especiajjyjin area%,of, known or, likely concentrations of tuna.. The gear had evolved from hand- l haul/ed, Jbulky, mainlines, fished singly, to, lighter, more, easily stowed material set with handreels, ^upg^ogeiher along the surface, and fished several at a time. ; r ,-... > *>

..! :. jt'.-jij^'-'f i'i'ji'ff- •'. . *-v< •'• :.' _'••• -• »'••-, - -' ' i " • • ' ' ••.•••' ' •'' '-•' '.'..,.... ' • • '•-'-••'"•

.•'.•-•!. 'i.llu.' h:)C '.:•• •.!..••• ,; ' ?- •> • ••••'.•''-(''•'' ' '•' ' ' " ' '' ' J ...... t • ,.•••,' Recent Innovations: Vertical Longlining in Tonga Substantia^ and significant innovations in gear and techniques have marked the Tonga component of verfiqaj lpngUjiing. Just as in deploying FADs, there are two options for setting vertical longlines, either, singer., )|rst or float first. „ Most sets in Yap\; Nuie, Cook Islands, and Fiji were sinker first. , In add^t^n^ the rate of lowering the mainline depends on several factors, depending on whether the boat ^sstationary (tied off a FAD).or drifting. When.tied to a FAD the most important factor affecting line siting is current strength. If the current is strong its possible to lower the mainline quickly because the current causes the snoods to stand downstream, and prevents them from tanking around, the _mainline- , When drifting, wind speed is the factor that regulates how rapidly the mainline can be'deployed, because wind speed generally regulates the rate of drift of the boat. A 5-8 knot wind is ideal for setting vertical longlines from a drifting boat. If wind speed exceeds 10 knots, its possible to slow the boat's drift with a parachute sea anchor.

With the sinker first method a fairly slow rate of setting must be maintained while both the upper and hoqk sections of the line is lowered into the water. -Otherwise snoods routinely tangle around the mainline. v Setting time is directly dependent on fishing depth. . ^ Much of the work in Tonga has focussed on streamlining setting operations to enable setting more hooks ip n shorter period of time, .even when current or wind conditions are not the most favorable. Qne< of the key elements in the new technique is a length of 8 mm polypropylene floatline with joins every, 50 fathoms. A float is capped to a loop in the join line and the vertical drop longline is ch;ppe4 into, another loop in .the join line located about .5 m behind the loop where the float is attached. Drops and floats are usually attached at 50 fathom intervals unless there is a shark problem. Once hooked, sharks immediately head toward the surface and swim in circles which tangles the gear excessively. In shark areas drop lines are spaced 100 fathoms until the sharks are fished down. The addition of two specially constructed wooden reels has sped up setting operations considerably. One reel is capable of storing 100 snoods, and the other has a storage capacity of 10 x 150 fathom drops. Both reel are mounted side by side toward the stern about 1 m aft of the steering cockpit. Toward the bow a .5 x .5 x 1.5 m plywood box is mounted to store 1000 fathoms of polypropylene floatline. The setting operation is to deploy the sea anchor with the 8 mm poly floatline attached. Run diagonally across the wind for 100 fathoms and maintain the port side as the upwind side. Attach a longline float at the 50 fathom join as the line is run out. Clip another longline float at the 2nd join. Next clip a vertical mainline to the spliced in loop in the floatline. Steam forward and pay out 8 mm poly line. Now both the mainline and the polyprope are playing out together. Once a swivel is reached a snood is baited, clipped to the swivel, and thrown into the water on the SPC/Fisheries21/WP. 30 Page 6

starboard side of the boat. More mainline is spooled off the reel - at the same rate as the float line, < a swivel is reached, a snood is clipped on, baited and thrown over the side. • The process is 'repeated until all the branchlines are attached. , -.

After all the baited branchlines are clipped on, and the end of the dropline is reached, a'1.5 - 2.0 kg rebar is looped bnto the bottom and the entire vertical longline is dropped over the side?'The sinker prevents branchline fouls because it sets up an artificial current which keeps the branchlines extended behind the sinking arc of line. The boat then steams along the floatkne to the drop line attachment adjacent to the attachment of the dropline just deployed. The whole sequence is repeated until perhaps 10 baited branchlines have been deployed. Under moderate sea conditions with two people working a single drop requires about 10 minutes time. , "!':;,"'wl '" Once the last vertical dropline has been baited and deployed, the boat is tied off on the 8 mm surface line 50 fathoms beyond' the last drop. A pole and flag can be attached to the 'end Of the floating line to enable the boat to patrol the line and look for heavy floats. If it looks like a fish is hooked the dropline is unsnapped from the floatline and slipped onto a modified'Sflmdan handreel and hauled. Snoods are disconnected as they break the surface. * Aftef checking and landing any fish, the dropline is slowly lowered and baited snoods are reattached. " Hauling the entire system starts with the last dropline set. Snoods are undipped, hooks stripped, and lines wound back onto the reel.

Conclusions: With a simple vertical longline system it's possible to concentrate hooks at specific depths in a limited area. The method is particularly suited for fishing tuna "holes", around FADs, and other locations such as the up current sides of seamount peaks where tunas are known to frequent. The system is easily adapted to small vessels^ and its constructed from readily available materials (plywood, hardwood, epoxy resin, etc.). The gear for the vertical droplines and shObds is available throughout the region. Also; the system is inexpensive. In Tonga, materials for a single complete dropline induding hooks, swivels, clips, nylon, and float, cost approximately T$'75.00, which is equivalent to A$ 75.00. The modest costs of construction and gearing up means that operations may be able to rely only on local markets and still be profitable.

* ) ^

150 - 200 kg nylon monofilament

\ No 36 or 3B tuna longline hook or No 48 BKN hook

3 fathoms 250 -300 lb 140 kg) test nylon mono

8mm kuralon loop spliced into bottom ring of swivel 8 fathoms (15 m) 150 - 200 kg nylon monofilament

Figure 1. Longline deployment method SPG/Fisheries 21/WP. 30 Page 8