The Shark Longline Fishery in Papua New Guinea
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SCTB16 Working Paper BBRG–2 The Shark Longline Fishery in Papua New Guinea (A paper prepared for the Billfish and By-catch Research Group, at the 176th Meeting of the Standing Committee on Tuna and Billfish, Mooloolaba, Australia, 9th – 16th July 2003) Ludwig Kumoru Papua New Guinea National Fisheries Authority, Port Moresby, Papua New Guinea June 2003 Introduction Shark fishing has a long history in Papua New Guinea, and in certain areas of the country, sharks have considerable cultural significance. Artisanal and community fishers have contributed to the trade in dried shark fins, whilst various larger scale fisheries for shark have operated in the more recent past. A drift net fishery for shark and other species operated in the Gulf of Papua during the early 1980s, but ceased as catch rates declined and international sanctions on drift net fishing were applied; a trial fishery for liver oil from deep water sharks was carried out in the early 1990s. The present shark longline fishery developed in the mid 1990s and comprises freezer longline vessels that were initially licensed as tuna longline vessels at the time the domestic tuna longline fishery was developing. These vessels, attracted by higher prices for shark products, especially fins, and a readily available market for shark meat, increasingly targetted sharks. This change in operations was regarded as unregulated fishing and in response, the National Fisheries Authority (NFA) in 2001, took steps towards introducing a Shark Longline Management Plan, which now governs the operation of the shark fishery in PNG. It is considered that a small well regulated shark fishery targeting primarily pelagic carcharhinid species is sustainable in the extensive EEZ of PNG. The shark fishery is now the fifth most valuable export fishery, after tuna, prawns, beche-de-mer and lobster, and is worth about K8 million (U$2 million) annually. The Fishery The fleet In past, up to 21 vessels (year 2000) have targetted shark, after initially operating in the tuna longline fishery. In 2002, the shark longline fishery, involving freezer vessels, was recognized as a separate fishery subject to a Management Plan. The fishery currently has nine freezer longline vessels, which were initially licensed as tuna vessels. They are mostly 20m to 30m LOA, and between 60 to 170 GRT (Table 1). All, except one, have fibreglass hulls and generally use between10 to 20 crew, mostly Papua New Guinean. Participation in the fishery is restricted to citizen companies Table 1 Vessels currently licensed to fish sharks in PNG Source:NFA records Vessel Name LOA (m) GRT No. Crew Hull Material Neptune 38 22 62.87 14 Fibreglass Neptune 68 22.6 75.88 14 Fibreglass Hung Hua No. 11 33.7 158.88 21 Fibreglass Weng Sheng No.1 29.66 172.00 19 Fibreglass Feng Jung Chin No.1 26.6 99.41 15 Fibreglass Chin Li No. 118 20.3 98.46 8 Fibreglass Wan Feng 20.2 96.79 10 Fibreglass Yu Fu No. 11 23.81 144.92 12 Steel Feng Jung No. 20 17.83 72.65 6 Fibreglass Fishing Operations Gear used The longline gear is set nearer the surface than is the case with tuna longline vessels, employing this and other techniques to more effectively target the various shark species. Two types of gear are deployed by various vessels in the fleet. The first is typical monofilament (400lb), with four hooks between baskets, a float line length of 15m, 10m branch lines and 60m between branch lines (1&2=60, 2&3=80 3&4=40). The 1 branch line comprises 1m 3 strand polypropylene, 1m monofilament (200lb), and 1m trace wire with hook. The second gear is the traditional tarred Kuralon (7mm), with a float line length of 40m, branch line length of 5m and distance between branch lines of 15 meters. The branch line material is 3 strand polypropylene (3mm) with similar terminal gear. Under the Management Plan, a maximum of 1,200 hooks per set, or 10,800 per day for the nine vessels, is permitted Based on observer data collected from 34 sets during 2002, an average hook depth of 72.3m (range 35-108m) was measured. Bait used in most instances is skipjack or kawakawa, purchased from Taiwan and delivered by the reefers that export the shark catch. Damaged tuna in the catch may also be used. Shooting and Hauling process Sets start normally in the afternoons and hauling in the early mornings. Setting takes about 4-5 hours and retrieval about 7-8 hours. Soak time is normally about 8-10 hrs. Shooting is done without line thrower, with manual retrieval of the branch lines. Catch handling & processing on board The sharks are electrocuted before hauling on deck. The fishermen use a grappling pole attached to a 110 volt wiring system to electrocute the sharks. Electrocution takes 25 to 30 seconds depending on the condition of shark. Once immobilized, the sharks are gaffed aboard. They are then headed, gutted, tailed and finned, and the carcass trimmed, typically leaving 60% of the original whole weight. The processed sharks are then blast frozen for 24 to 36 hours in the contact freezers before storage in the fish holds. Fins are removed for freezing, and make up around 6% of the whole weight. Tunas and billfish are similarly headed and gutted, then frozen. Catch details Catch data Prior to 2002, logsheet coverage of the fishery was poor (<30%), partly because the available tuna longline logsheet made little allowance for accurate recording of the shark catch. Logsheets for the shark longline fishery were introduced in 2002, and coverage has improved but remains incomplete, with species composition not yet accurately recorded on the new catch forms. Observer data remains the best source of information on fishing operations and species composition of the catch. Total catch Estimates of the shark longline catch for 2002, based on available logsheet data for 3 vessels and landings data for six vessels indicate a total catch of 1,965t, of which shark (dressed weight) made up 1,530t, tunas 119t and billfish 251t. This compares with recorded exports (shark meat) during 2002 of 1,328t as at June 2003, with increasing quantities of shark known to have been processed in PNG for local consumption during 2002. Based on the available export data, possibly incomplete, catches prior to 2002 were larger than this, peaking in 2000, when 21 vessels operated full or part time in the fishery and 1,747 of shark meat was recorded as being exported. The fishery has taken over 2,000t whole weight of shark since 1999, based on the export data. Catch Composition Shark makes up more than 80% of the catch by weight, with tuna and billfish comprising the balance of the catch, along with a range of other fish species (Table 2). The tuna catch is mostly yellowfin tuna, whilst swordfish, blue marlin and sailfish 2 dominate the billfish catch. Barracuda and deep bottom snappers are most common of the range of other species taken. Most of the catch of all species groups is retained. Table 2: Species composition and fate of the main group of fishes in the PNG shark longline fishery (Source: SPC observer data for trips before 2002; fate % may not total 100% since data not recorded for some captures) SPECIES COMPOSITION FATE SPECIES No.% Wt.% CPUE Ret % Disc % SHARKS 78.0 80.7 34.87 83 11 TUNA 5.5 5.9 2.47 83 10 BILLFISH 6.5 8.4 2.90 86 10 OTHERS 9.8 4.8 4.41 81 13 MARINE TURTLES … … … 0 100 MARINE MAMMALS … … … 0 100 *Total observed HOOKs for period prior to (01 Jan 2002) 374,659 hooks *Total observed SETS for period prior to (01 Jan 2002) 355 sets *CPUE Number per 1,000 hooks * … Greater than zero (0), but less than resolution allows The main shark species taken are oceanic in habitat (Table 3), although the fishery operates close to seamounts and non-emergent reefs which are not defined in the Management Plan. Based on observer data, silky sharks (C.falciformis) and oceanic white tip (C.longimanus) dominate the shark catch by weight (58%), but some more coastal species, such as grey reef sharks (C.amblyrhynchos) and silvertip (C.albimarginatus), are also taken in significant numbers, along with a range of other species such as blacktip, hammerhead, blue, thresher, mako, tiger, and crocodile sharks plus some pelagic rays. The fins and meat of most species are marketable, but the meat of some species is of low value e.g. blue shark and may not be retained. Table 3. Species composition of the shark catch and fate of the main shark species taken (Source: SPC observer data for trips before 2002; CPUE as nos. per 1,000 hooks; fate % may not total 100% since data not recorded for some captures) Trips prior to 01 Jan. 2002 SPECIES COMPOSITION FATE SPECIES No.% Wt.% CPUE Ret % Disc % SILKY SHARK 49.3 47.4 17.00 94 4 OCEANIC WHITETIP SHARK 9.1 10.9 3.15 84 8 GREY REEF SHARK 11.2 9.0 3.85 81 6 BLACKTIP SHARK 8.7 3.6 3.03 86 13 SILVERTIP SHARK 6.2 4.8 2.17 88 11 HAMMERHEAD SHARKS 4.8 7.9 1.68 68 26 BLUE SHARK 2.2 2.8 0.8 12 73 OTHER SHARKS 8.5 13.6 4.1 59 39 Area of fishing and species distribution The fleet operates over most parts of PNG waters, outside 6 miles of land and associated reefs, as required under the Management Plan.