16

MANAGEMENT OF SHARK FISHERIES IN NORTHERN AUSTRALIA

J.D.Stevens
CSIRO Division of Marine Research, GPO Box 1538, Hobart,
Tasmania 7001, Australia

1. INTRODUCTION

1.1 Distribution of the fishery

1.1.1 Foreign fisheries

A Taiwanese gillnet fishery operated in offshore waters of northern Australia between the Northwest Shelf and north of the Gulf of Carpentaria (GoC) from 1974 until mid 1986 (Stevens and Davenport 1991). Before 1978, the Taiwanese fished throughout northern Australian waters, to within 12 nautical miles (22km) of the coast, from the North West Shelf to Cape York. In August 1978, the GoC was closed to foreign fishing. With the declaration of the Australian Fishing Zone (AFZ) in November 1979, the permitted fishing area included waters from the Monte Bello Islands to the western end of Torres Strait and at least 12nm from the Australian coast (Figure 1). The gillnetters were excluded from an area around Melville Island and from within 25nm (46km) off Eighty Mile Beach (Western Australia)(Figure 1). In November 1980, the area of exclusion off Arnhem Land and the Wessel Islands was increased to between 30 and 40nm (56 and 74km) from the coast, and Joseph Bonaparte Gulf was closed to Taiwanese gillnetters. In August 1983, all vessels were restricted to grounds north of 18°S.

Figure 1

Area of Taiwanese gillnetting in Northern Australia

Indonesian vessels also fished for shark in northern Australian waters prior to the AFZ. Today, there is limited access by traditional Indonesian fishers to an area off north western Australia known as the MOU (Memorandum of Understanding) Box. There is also some illegal Indonesian fishing within the AFZ.

1.1.2 Domestic fishery

The main area of the Northern Shark Fishery (NSF) extends from 123°45'E in Western Australia (WA) to Cape York, Queensland (141°20'E). Most of the fishing activity is concentrated in inshore areas of Joseph Bonaparte Gulf, Fog Bay, Van Diemen Gulf and from the Goulbourn Islands to the southern GoC (Clarke 1996). Some fishing occurs down the Western Australian and the east Queensland coast (Figure 2). The majority of fishing is within 36km of the coast in depths from 15– 70m. Prior to the Offshore Constitutional Settlement (OCS) in February 1995, the NSF was managed as a single unit between 123°45'E and 141°20'E under complimentary Commonwealth and State/Territory controls. As a result of the OCS (Australian legislation which related to jurisdictional responsibilities between the Commonwealth and States/Territory), the fishery is managed as three separate Commonwealth - State/Territory Joint Authorities (Caton et al. 1997; McLoughlin et al. 1993, 1994). The zone from 123°45'E (Koolan Island) to the WA/Northern Territory (NT) border (129°E) is controlled by Joint Authority between the Commonwealth and WA. From 129°E to 138°E is managed by the Commonwealth and NT and from 138°E to 141°20'E by the Commonwealth and Queensland. The area west of 123°45'E to 114°06'E is managed by WA (Figure 2). The Queensland East coast fishery has no specific shark management plan and the shark fishery is covered by the inshore east coast and Gulf net licence. Shark fishing extends as far south as Hervey Bay (25°S) (Kailola et al. 1993).

Figure 2

Northern Australian Shark Fishery (WAF - Western Australian Fishery; WAFJA - Western Australian Fishery Joint Authority; NTFJA - Northern Territory Fishery Joint Authority; QFJA - Queensland Fishery Joint Authority; QF - Queensland Fishery)

1.2 Species composition of the fishery

i. Taiwanese fishery

The Australian blacktip shark (Carcharhinus tilstoni), the spot-tail shark (Carcharhinus sorrah) and the longtail tuna (Thunnus tonggol) comprised about 70% by number of the Taiwanese gillnet catch in the AFZ (Stevens and Davenport 1991). Scomberomorus spp., which together with sharks and tuna were a target group, represented about 5% of the catch by number (Table 1). Carcharhinus tilstoni accounted for a considerably higher proportion (54%) and C. sorrah a considerably lower proportion (10%) of the catch in the Wessels area, while the proportion of T. tonggol was highest in the Arafura Sea (21%) (Table 1). Sharks, tuna and mackerel comprised about 63%, 26% and 6%, respectively, of the catch by weight in the AFZ. About 20species of shark, a few batoids and a considerable diversity of teleosts are taken by the fishery although teleost numbers are generally low with the exception of Scomberomorus spp. The species composition from some longline fishing carried out by the Tawanese in 1990 and 1991 is shown in Table 2.

The relative abundance of the two target species in the catch varies with fishing method. C. †tilstoni predominating in gillnet catches while C. sorrah is more abundant in longline catches (Table 3) (Anon 1990). However, this difference in species composition was not evident in the Taiwanese longlining further offshore (Table 2).

ii. Domestic fishery

Fishery independent research data from the Northern Pelagic Fish Stock Research Programme show that C. tilstoni and C. sorrah comprised 53% and 19%, respectively of the total gillnet catch by number (Anon 1990). Carcharhinus tilstoni accounted for 24–74% of the shark catch by number in gillnets depending on area, and this shark comprised the highest proportion of the catch on the Queensland east coast, in the GoC and inshore waters of the NT (Anon 1990). Carcharhinus sorrah comprised a relatively higher proportion of the catch in the GoC and in inshore waters of the NT. Catches from north western Australia, which were mainly from Napier Broome Bay, contained proportionately more hardnose shark (Carcharhinus macloti) than the other regions (Anon 1990)

The research data suggests there is also a relationship between depth and relative catch composition from gillnets. Carcharhinus tilstoni comprised the highest proportion of the catch by number in the four depth ranges examined, less than 20m, 20–29m, 30–39m and more than 40m. Carcharhinus sorrah accounted for only 10% of the catch in less than 20m while it represented between 19–29% of the catch in the deeper zones. Carcharhinus macloti showed a proportionately higher representation in catches from both the shallowest and the deepest depth zones. Of the other sharks that occurred in reasonable numbers, the graceful shark (Carcharhinus amblyrhynchoides) and the milk shark (Rhizoprionodon acutus) represented a higher proportion of the catch in shallow water (Anon 1990).

Northern Territory logbook data indicates that blacktips, hammerheads and milk sharks comprise 72, 2.4 and 0.3% of the catch on average. Down the east Queensland and WA coast, the species composition is likely to be somewhat different although blacktips are still well represented in the catch. No detailed species composition data are available but in the WA zone between 114°06'E and 123°45'E, C. tilstoni, C. sorrah, C. plumbeus, C. obscurus, Galeocerdo, Carcharias taurus and Sphyrna spp. are known to be taken.

1.3 Biology of key species

Carcharhinus tilstoni

Carcharhinus tilstoni is a medium sized whaler shark attaining about 200cm total length (TL) which is currently known only from the continental shelf of tropical Australia (Last and Stevens 1994). It is found from close inshore to a depth of about 150m and ranges throughout the water column although it is most common from near the surface to midwater. This species is very similar to the common blacktip shark (Carcharhinus limbatus) and at the moment can only be reliably separated from it by genetic techniques or vertebral counts (Lavery and Shaklee 1991). Carcharhinus tilstoni is born at about 60cm TL and grows relatively quickly increasing by about 17cm in the first year and reaching sexual maturity in 3–4 years at a size of 110cm in males and 115cm in females; longevity is about 20 years (Stevens and Wiley 1986; Davenport and Stevens 1988). Carcharhinus tilstoni is viviparous and the embryos are nourished via a yolk sac placenta. The reproductive cycle is distinctly seasonal with mating in February-March, ovulation in March-April and the main birth period in January. The average litter size is three (range 1–6), the gestation period is 10 months and individual fish breed each year. There do not appear to be spatially restricted pupping or nursery areas as new-born fish are widely distributed both in inshore and offshore areas. Based on catch data, C. tilstoni occurs in groups that are sometimes composed predominantly of one sex or size range, sometimes with small spatial distibutions. Genetic studies have shown that there is only one stock of C. tilstoni off northern Australia and tagging studies show that while the maximum distance travelled was 1348km, 60% of fish were recaptured within 50km of their tagging site (Lavery and Shaklee 1989; Stevens unpublished data). Smaller sharks tended to move greater distances than larger sharks. The diet of C.tilstoni consists of teleost fishes, and to a lesser extent, cephalopods. The proportion of cephalopods in the diet is greater in larger sharks which feed in midwater and near the surface to a greater extent than small sharks which contained a higher proportion of demersal species in their stomachs.

Carcharhinus sorrah

Carcharhinus sorrah is a medium sized whaler shark attaining about 160cm TL with a tropical Indo-West Pacific distribution. In Australia, it occurs north of about 25°S over shallow continental and insular shelves from the intertidal area down to about 80m depth (Last and Stevens 1994). It is common in open areas over muddy bottoms, but also occurs near coral reefs. It ranges through the water column but it is caught more frequently in midwater or near the surface, often in sex or size segregated groups. Carcharhinus sorrah is born at about 50cm TL and grows relatively quickly increasing about 20cm in the first year to reach sexual maturity in 2–3 years at a length of 90– 95cm TL. After some five years of age, growth declines to 5cm a year or less; longevity is about 20 years (Stevens and Wiley 1986; Davenport and Stevens 1988). Carcharhinus sorrah is viviparous and the embryos are nourished via a yolk sac placenta. Reproduction is distinctly seasonal with mating in February-March, ovulation in March-April and the main birth period in January. Litters of three pups (range 1–8) are born after a gestation period of 10 months and individual fish breed each year. New-born fish are widely distributed both in inshore and offshore areas suggesting that nursery areas are not confined to specific regions. Genetic studies show that there is only one stock of C. sorrah in northern Australia and although tagged fish moved distances of up to 657km, about 50% were recaptured within 50km of their tagging site (Lavery and Shaklee 1989; Stevens unpublished data). The diet of C. sorrah consists of teleost fish and to a lesser extent cephalopods and crustaceans.

1.4 Associated species (bycatch or discards)

In addition to C. tilstoni and C. sorrah, some 25 species of sharks, 25 species of teleosts and a few batoids are taken by the fishery (Table 3). In the Taiwanese fishery most sharks, with the exception of the tiger shark (Galeocerdo cuvier) and very small specimens of any species, were retained for their meat; fins of all but the smallest sharks were retained. Scomberomorus spp. and Thunnus tonggol were retained but most other teleosts were discarded or used onboard for the crew. Other bycatch included turtles and cetaceans; it was concern over the bycatch of cetaceans which resulted in net length restrictions being imposed on the fishery.

The domestic fishery discards most of the smaller species of shark such as Rhizoprionodon spp. and C. macloti as well as some Sphyrna spp., Galeocerdo and Stegastoma: fins are retained from all but the smallest specimens. Of the teleosts, Scomberomorus spp. are an important bycatch. Because of the relatively small net lengths, cetaceans are rarely caught in the fishery.

1.5 Discussion

The NSF is a multispecies shark fishery that operates in the northern part of the country with complex shared jurisdictional arrangements between the Commonwealth and the States/Territory. Of the two target blacktip sharks, one is endemic and the other has an Indo-West Pacific distribution. Teleosts are not targeted but Scomberomorus spp. are a desirable bycatch.

The biology of the target species are reasonably well known (Stevens and Wiley 1986; Davenport and Stevens 1988; Lavery and Shaklee 1989; McLoughlin and Stevens 1994; Stevens unpublished data) but less information is available for many of the other sharks taken by the fishery (Lyle 1987; Stevens and Lyle 1989; Stevens and McLoughlin 1991).

There is a reasonably high level of utilisation of the catch and the relatively short net lengths and set times means there is less wastage of the product. Bycatch of other groups such as turtles, sea birds and cetaceans does not appear to be a significant problem in the current NSF.

2. DEVELOPMENT OF THE FISHERY AND CURRENT FISHING PRACTICES

2.1 Evolution of the harvest process and fishing fleet

The northern Australian shark resource was initially exploited by a Taiwanese gillnet fishery which operated in offshore waters of northern Australia between the North West Shelf and north of the GoC from 1974 until mid 1986. Fishing effort was concentrated north of the Wessel Islands. The Taiwanese fished primarily for shark, T. tonggol and Scomberomorus spp. The product was marketed in Taiwan, chiefly for domestic consumption, although some was exported.

The Taiwanese gillnetters were steel vessels of 160 to 380t, 30 to 45m long. They included converted Taiwanese longliners and stern trawlers as well as purpose-built gillnetters. Millington and Walter (1981) give a general description of the layout of the vessels.

When the AFZ was declared in 1979, the fishing area and vessel numbers were restricted, and a catch quota was implemented for a limited number of licensed gillnetters.

The surface-set gillnets were of multifilament nylon with a diagonal stretched mesh between 14.5 and 19.0cm. The net lengths increased from about 8km in 1979 to about 16km in late 1985, with some nets longer than 20km. The nets fished at about 15m depth (range 8–18m) in 1980 to about 20m in 1986. For every kilometre of headline about 50 polystyrene buoys (30cm diameter) were attached. The buoy lines were usually 1-2m long, but could be varied to fish the net from surface to sub-surface. Between late 1983 and early 1985, there was a transition to smaller torpedo floats attached directly to the headline, effectively bringing the net to the surface. The net was hauled by a power block, the efficiency of which was upgraded when longer nets were used. The nets were set just before dusk, setting taking 1-2h. They were allowed to drift until hauling began around midnight, which generally took 6–9h but could take as long as 16h, depending on the size of the catch. Details of the fishing operation are provided by Millington and Walter (1981).

Tuna and mackerel were stacked whole in the freezer; on some vessels the caudal fins were trimmed first. Sharks were trunked, gutted and had their fins removed before freezing. Fins from all but the smallest sharks were retained and either frozen or dried in the sun.

In 1986, the Australian Government introduced legislation limiting the length of gillnets to 2.5km, to reduce the bycatch of dolphins. This action rendered the Taiwanese gillnet fishery uneconomic and, despite some attempts to switch to longlining as an alternative, the Taiwanese vessels had ceased shark fishing in the AFZ by mid-1986. Subsequently, a joint-venture longline operation using eight Taiwanese vessels took place from February 1990 to September 1991.

Direct involvement in the NSF by Australian gillnet vessels began about 1980. Initially, the Commonwealth managed the use of gillnets and longlines throughout northern Australia, with the NT responsible for the inshore fishery extending to 12nm offshore for pelagic gillnets and 3nm offshore for demersal longlines. The few vessels initially operating in the fishery were generally 15–20m in length and the monofilament gillnets were set near the surface at night with set times generally being a few hours. Nets were 1200–2000m long and of about 150mm stretched mesh and 100 mesh drop. The net was usually weighted with lead-core rope and the headline buoyed with floats. Gillnets were hauled and stored on hydraulically powered net-reels usually mounted at the stern of the vessel. A limited amount of longlining was also done; while catch rates were generally not as high as in gillnetting the sharks were more often alive when caught and the product was in better condition.

Sharks were processed on board and either frozen, chilled, or put in brine, and landed as trunks or fillets. Most of the product was sold as ‘flake’ through the southern Australian domestic market.

Until February 1995, the fishery was managed under the Northern Shark Fishery Development Plan with complimentary Commonwealth and State/Territory controls. Permits were issued for the GoC zone, Arafura zone and the WA zone (Timor Sea region west of the WA/NT border). As a result of the OCS, responsibilities changed and three separate Commonwealth-State/Territory Joint Authorities were set up with each managed under State or Territory law. Currently there are some 38 licences in the NT zone, although four or five main gillnet vessels of about 15–30m in length take most of the catch in NT waters. There is still new interest in the fishery and new markets are developing for a range of products other than flesh, including fins, cartilage, livers and skin (Caton et al. 1997). In the northern WA Joint Authority zone from 123°45'E to the NT border droplines, longlines and gillnets are permitted. The area 123°45'E to 114°E is controlled by WA and only droplines and longlines are allowed. About six fishers have access to one or other of these zones. Shark is also a major component of the Kimberley gillnet and barramundi fishery.

There are about 1100 net licences in Queensland (there is no separate shark licence) with up to 65 boats catching some shark in the GoC, although there are only 3-4 main operators. There is a developing northern Queensland east coast-shark fishery which operates using coastal and offshore gillnets up to 1200m long. Handlines are also used to catch shark from trawlers at night. Around 350 boats are currently reporting shark landings on the east coast. Sharks are either sold wholesale as trunks or processed on-board and sold direct to retail outlets. Fins are dried or frozen and either exported to Asian markets or sold locally. In some areas cartilage, skins and jaws are also marketed (Kailola et al. 1993).

Sharks are also taken by the Northern Prawn Fishery (NPF); the area of operation of the NPF overlaps that of the NSF. In 1988, the shark and ray bycatch in the northern prawn fishery in waters adjacent to the NT was estimated at 2612t (Pender et al. 1992). Eleven families of sharks and rays were recorded including 1864t of shovelnose rays and shark rays (Rhynchobatidae), 305t of carcharhinid sharks and 294t of stingrays, (Dasyatidae). Most of the bycatch was discarded at sea with only carcharhinid and hemigaleid sharks retained for the domestic market (trunked and sold as blacktip sharks) and fins (particularly from shovelnose rays) retained for the Asian market. The retention of shark bycatch, particularly for the lucrative fin market, had increased in recent years. Prawn trawlers often targeted sharks with hook and line which had been attracted to the boat during hauling of the trawl. Much of this shark catch for fins was unrecorded. Bycatch restrictions in the NPF currently limit the amount of shark retained on-board at any one time.

Sharks are frequently taken as bycatch of dropline, longline, handline, haul net, bait net and barramundi fishing in northern Australia. There is also limited access by traditional Indonesian fishers to an area off north western Australia. The amount of catch taken by these vessels, as well as by illegal Indonesian fishing in the AFZ, is unknown but it is thought that the species composition of sharks is different to that taken by domestic vessels (Caton et al. 1997).

2.2 Evolution of the catch

2.2.1 Taiwanese fishery

The annual catch of the Taiwanese gillnet fleet in the area between northern Australia and Papua New Guinea averaged about 25 000t live weight mainly of shark, tuna and mackerel before management measures were introduced. With the declaration of the AFZ a quota of 7000t processed weight (10 000t live weight) a year was allocated to 30 gillnetters for a season from November 1979 to October 1982, under a bilateral agreement. The quota was set at 5250t for a nine month period from November 1982, and reduced to 5000t for the 12 months from August 1983 to allow for pending joint-venture proposals. Eight joint-venture vessels were allocated a 2000t quota from October 1983 to August 1984. The Taiwanese catch from 1974–1986 is shown in Table 4. Between February 1990 and September 1991, 1700t of shark were landed by eight Taiwanese longliners licensed under a Joint-venture agreement.

* Shark catch weighted up to 100% from subset of data (71%).

2.2.2 Domestic fishery

Table 5 shows reported shark landings for the Northern territory shark fishery for 1983–1996 and Table 6 shows reported landings for the Gulf and East coast.

The 1995 catch (Table 7) comprised 43t from the WA area, 57t from the Joint Authority area and 112t of shark and ray from the Kimberly Gillnet and Barramundi Fishery (KGBF). In 1996, there was 122t from the KGBF and 38t from the WA and Joint Authority area. The species breakdown of catch in 1996 was 59.8t of blacktip, 6.6t of Carcharias taurus, 5.7t of Sphyrna spp., 17t of Carcharhinus plumbeus, 6.1t of Galeocerdo cuvier, 33.8t of other shark and 27.9t of skates and ray. There are problems in accessing some of the catch data at present and there may also be some double counting of catch between adjacent areas in the fishery. Total targeted catch for the NSF in 1995 was about 1600t live weight.

The elevated catch levels of 872t of blacktips (303, 425 and 144t in the NT, GoC and Arafura zones, respectively) in 1992 are attributed to management arrangements requiring operators to establish pre-determined minimum catch criteria to continue in the fishery.

* To convert trunk weight to live weight multiply by 1.5

2.3 Evolution of fishing effort

i. Taiwanese fishery

Gillnet fishing effort by the Taiwanese (Table 8) peaked in 1983, after falling to a low in 1979 and then recovering. At the end of the fishery in 1986, effort was only 26.2% of that maximum value only 4 years earlier.

ii. Domestic fishery

In the domestic fishery, Northern Territory vessel effort increased rapidly after 1984 though it has not been without variation (Table 9). Maximum recovered effort was in 1987. In Queensland, in somewhat of a contrast, greatest effort has been expended in the last years for which data are available, 1993–1995 (Table 10).

There are currently no effort figures available for the WA fishery areas (WAF and WAFJA) from 114°06' to 129°'E.

2.4 Markets

2.4.1 Introduction

During the years of the Taiwanese fishery sharks were trunked, gutted and had their fins removed before freezing. The product was marketed in Taiwan, mainly for domestic consumption, although some was exported. Fins from all but the smallest sharks were retained and either dried or frozen (Stevens and Davenport 1991).

In the domestic fishery, sharks are processed on board, either frozen, chilled or placed in brine and landed as trunks or fillets. Shark is traditionally marketed as ‘flake’ in southern Australia where it is used in the ‘fish and chip’ trade. The flake market is mainly supplied by the Southern Shark Fishery which targets school (Galeorhinus galeus) and gummy (Mustelus antarcticus) shark. Following acceptable results from consumer testing of northern shark on the southern market (Welsford et al. 1984), most of the product was initially sent through the Melbourne market, although some was sold in the NT as ‘blacktip shark’. Currently most shark and mackerel from the NSF is arketed in southern and eastern Australia, although some is exported. Fins are exported to SE Asia. Some new markets for the meat are appearing but these tend to be fairly volatile. In the NT, the main operators do their own market research. There are some limited markets for skins, cartilage and livers. In the Melbourne market, northern shark currently fetches about $3.50 – $4.00/kg with medium sized school and gummy shark fetching $7.00/kg and large school shark $6.00/kg.

The Queensland wholesale price for shark in 1992 averaged A$2.00–3.00/kg. Fins are retained from all but the smallestsharks, dried or frozen and either exported (mainly to Asian markets) or sold locally (Kailola et al. 1993). In 1990, shark fin sold in Australia fetched A$ 12.00-65.00/kg dried (Darwin wholesale prices). During 1992, the overseas price for top quality dried fin exceeded A$100.00/kg. In the Queensland east coast fishery, sharks are either sold wholesale as trunks for A$1.50–3.00/kg or processed on-board and sold direct to restaurants and retailers for A$4.50–6.00/kg (Kailola et al. 1993). The amount of batoids kept as bycatch and marketed as shark is unknown. The Queensland Health Department determined that a substantial proportion of ray was mixed with shark in the 1993 east coast landings (Williams 1997). Northern shark from WA is currently fetching about $3.00/kg.

There are maximum permissible concentration standards for mercury levels in shark throughout Austalia (0.1mg/kg). A 1993 Queensland Health Department report determined that 17% of Queensland shark could still exceed Australian standards (Williams 1997). Current levels of mercury in sharks from Queensland are unknown but concentrations in NT shark have been reported by Lyle (1984a, 1984b, 1986).

2.4.2 Revenues from the fishery

Marketing problems in the sale of shark meat have hindered expansion of the fishery. In recent years the escalating price of shark fins has changed the characteristics of the fishery such that revenue from fins now approaches that of the meat. In 1992, the commercial value of the NSF was reported to be A$600 000, in 1994 it was A$1.5 million and in 1995 and 1996 the Northern Territory NSF catch was worth between A$2.3–3.0 million (McLoughlin et al. 1993, 1994; Clarke 1996; Caton et al. 1997). Shark production figures for the NT reported in the Australian Bureau of Agricultural and Resource Economics (ABARE) fishery statistics (Anon 1991–97) are shown in Table 11, and for 1995-96 are considerably lower than the A$2.3–3.0 million reported above.

In 1994/95 the ex-vessel value of the WA northern shark fishery was $0.61 million. In 1995/96 the value was $0.77 million of which the State controlled area was worth $194 000, the Joint Authority area $ 171 000 and the KGBF $404 100. These values do not include fins, for which a conservative estimate for 1995/96 is $212 000 (Penn 1997). In 1996/97 the WA fishery was worth $0.43 million of which the KGBF was worth $308 246 and the combined State and Joint Authority area $119 937.

2.5 Economics of the fishery

There has been no economic survey of the NSF to estimate harvest costs or profitability. However, the main operators are currently continuing in the fishery and there is still interest in purchasing licences. In the NT, licences are not directly transferable as there is a 3:1 effort reduction programme in place. To enter the fishery an operator has to buy and surrender three restricted licences for the issue of a transferable licence as a means of removing latent effort from the fishery. The fishery contributes to the economy of the States/Territory, and the Autralian government through taxes on profits.

2.6 The fisheries workforce

Of the approximately 40 shark licences in the main area of the fishery between 123°45’°E and 141°20'E about 10 are full time shark fishers, the remainder of licence holders participate on a part-time basis. On the east Queensland coast, some 1100 people hold inshore net licences but only about 20 boats fish principally for shark. Vessels range in size from 6–35m and usually have a crew of 2–4, including the skipper. Some of the largest boats have a crew of 6–10. Of the full-time operators some employ a skipper, while most vessels are owner operated. Crews are usually employed on a share-fishing basis with their wages determined by trip expenses and profits.

3. MANAGEMENT OBJECTIVES

3.1 The fisheries and government fishery policy

The main area of the fishery is currently controlled under three joint Authorities between the Commonwealth, WA, the NT and Queensland and managed under State/Territory law. Under the OCS there are Memorandums of Understanding (MOU) between the relevant governments which describe the mechanisms-for co-operating and collaborating on management of the shark resource in accordance with the principles of ecologically sustainable development. The State and Territory ministers have entered into formal agreements for the complimentary and co-operative management by adjacent authorities in the fishery. The Memoranda are to be read in conjunction with -

• the Fisheries Act 1994 (Queensland)
• the Fisheries Act 1988 (Northern Territory)
• the Fish Resources Management Act 1994 (Western Australia)
• the Fisheries Management Act 1991 (Commonwealth)

The objectives of these Fisheries Acts include:

• conserving fish and protecting the environment
• ensuring the sustainable exploitation of fish resources
• management of fishing, aquaculture and associated industries and aquatic ecotourism
• fostering the development of commercial and recreational fishing and aquaculture
• achieving the optimum economic, social and other benefits from the use of fish resources
• providing for the control of foreign interests in fishing, aquaculture and associated industries.

3.2 Management objectives of the northern shark fishery

Management objectives of the Commonwealth, States and Territory Fisheries Acts, and of the various Memoranda of Understanding under the OCS, apply to the NSF. For example, the NT Fishery Joint Authority “has the function of keeping constantly under consideration the condition of the fishery, formulating policies and plans for the good management of the fishery, and for the purposes of the management of the fishery, exercising the powers conferred on it by this act (NT Fisheries Act) and co-operating and consulting with the other authorities including other Joint Atuhorities within the many of the Commonwealth Act, in matters of common concern” (Clarke 1996).

Management advice is provided through the NT Shark Fishery Management Advisory Committee, the Queensland Fisheries Advisory Committee and the WA Fishery Joint Authority. A number of workshops have been held on stock assessment of northern shark and on northern Australian fisheries management and these workshops are linked to the MOU arrangements between the Commonwealth, States and Territory.

3.3 Discussion

Currently the NSF is not managed as a single unit but rather as three separate Joint Authorities. Fishing extends down the Queensland and WA coasts outside the main area of the fishery. This leads to a complex jurisdictional situation with no one body responsible for overall management; it also makes it difficult to define the boundaries of the fishery.

4. MANAGEMENT POLICIES AND THE POLICY SETTING PROCESS

4.1 Management policies

No management of the northern shark resource existed prior to 1978 other than legislation preventing the Taiwanese from fishing closer than 12nm from the coast. In August 1978, the GoC was closed to foreign fishing to prevent interference with the NPF. With declaration of the AFZ in 1979, Taiwanese vessels required licences to fish within the zone and the areas in which they could fish were restricted. A quota was set in agreement between the Australian and Taiwanese governments. From 1979–1986 there were minor adjustments to the quota in line with a change from a bilateral to a Joint-venture agreement aimed at encouraging greater Australian involvement in the fishery. In 1986, the Australian government imposed net length restrictions because of concerns over the bycatch of cetaceans. Some limited longlining continued until 1991 after which no further licences were issued to the Taiwanese.

In 1992, a development plan was introduced to encourage Australian participation in the NSF which was managed by the Commonwealth with complimentary State and Territory controls. Fishing endorsements were required for the three defined zones of the fishery which extended from 123°45'E to 141°20'E. In 1992, a total of 30 permits were approved for these three zones, five in WA, 16 in the NT and nine in the GoC. While sharks were the target species, the development plan applied to all species taken by the three fishing methods used, gillnetting, longlining and droplining. State responsibility for northern shark extended out to 12nm for pelagic gillnet and out to 3nm (5.5km) for demersal longliners. Fishers required endorsements for different shark fishing methods. Restrictions on net length, mesh size and areas also applied. In 1994, a total of 39 licences were issued, 13 in the Arafura zone, 9 in the GoC and 17 in the coastal NT zone (Northern Australian Fishery Management Workshop, Cairns, September 1996); not all of these were active.

From 123°45'E to 114°06'E is under WA control, and is managed under the Fish Resources Management Act 1994. Ten licence endorsements were issued for catching sharks by dropline (single hook sharklines) and longline; gillnets are not allowed. On the east coast of Queensland there is no specific shark management plan. The fishery is covered by the inshore east coast and Gulf net licence which is still open access. There are, however, gear restrictions and a closed season. Currently there are about 1000 licences but only about 20 dedicated shark operators.

In February 1995, management of the NSF was changed through the OCS agreement between the Commonwealth and Queensland, NT and WA. The fishery is now managed under State/Territory law as three separate Joint Authorities. Consequently, the NSF no longer exists as a management entity, but the agreement between the Commonwealth and State/Territory, and those between adjacent State/Territory management agencies, obligate those governments to co-operate on matters of mutual interest. While day-to-day management is vested in the States/Territory, major changes require the approval of both Joint Authority partners. Current management arrangements recognise the previous boundaries of the inshore NT, GoC and Arafura zones. Most operators have entitlements for more than one zone.

Bycatch restrictions in the NPF currently limit the amount of shark and shark fin that can be retained on-board at any one time.

The NT Shark Fishery Management Advisory Committee, recognised under the OCS arrangements and established in October 1992, is a major provider of advice on management of the fishery. The Committee comprises members from industry, management, compliance and research and meets once or twice a year on an ‘as-needed’ basis. A similar role in the Queensland Fishery Joint Authority is carried out by the Fisheries Advisory Committee which includes an independent chairman, commercial representatives from the net and line sector, a scientific advisor and an advisor on Aboriginal affairs. There is no formal advisory committee for northern shark in WA, but the WA Fishery Joint Authority meets once a year for discussionsbetween the delegates of the Federal and State ministers. As there are only four authorised fishers they are consulted directly if necessary, but they do not attend the meeting.

4.2 Policies adopted

4.2.1 Resource access

i. Foreign fishery

Access to the northern shark resource was unrestricted prior to declaration of the AFZ in 1979 and Taiwanese gillnetters fished most northern waters. With declaration of the AFZ, a quota was allocated to 30 gillnetters from November 1979 to October 1982, under a bilateral agreement. Eight Joint-Venture vessels were allocated a quota from October 1983 to August 1984. Gillnetters were effectively excluded from the AFZ in May 1986, but limited Taiwanese longlining continued until 1991. Traditional Indonesian fishers have access to a limited area off north western Australia.

ii. Domestic fishery

In the NT, the shark fishery became limited entry in 1990 when a moratorium was announced on the issuing of further gillnet and longline shark licences. The number of NT shark licences is currently limited to 38. In 1992, the development plan for the NSF required fishing endorsements for the three defined zones of the fishery which extended from 123°45'E. This is still the case following the OCS agreements. On the Queensland east coast the fishery is still open access. The WA managed boundaries are dependent on the type of gear used with the State controlling dropline fishing from 114°06'E to the NT border (129°E) and longline fishing from 114°06'E to 123°45'E. Longline and gillnet fishing from 123°45'E to the NT border is managed by the Joint Authority fishery (Penn 1997).

4.2.2 Closed areas

i. Foreign fishery

Before 1978, the Taiwanese fished throughout northern Australian waters to within 12nm of the coast, from the North West Shelf to Cape York. In August 1978, the GoC was closed to foreign fishing. With the declaration of the AFZ in November 1979, the permitted fishing area included waters from the Monte Bello Islands to the western end of Torres Strait and at least 12nm from the Australian coast (Figure 1). The gillnetters were excluded from an area around Melville Island and from within 25nm (46km) off Eighty Mile Beach (WA) (Figure 1). In November 1980, the area of exclusion off Arnhem Land and the Wessel Islands was increased to between 30 and 40nm (56 and 74km) from the coast, and Joseph Bonaparte Gulf was closed to Taiwanese gillnetters. In August 1983, all vessels were restricted to grounds north of 18°S. After 1979, traditional Indonesian vessels were only permitted access to an area off north western Australia.

ii. Domestic fishery

Fishers can only operate within the areas of the fishery for which they are licensed. Following OCS agreements operators no longer require a separate endorsement for Commonwealth waters.

4.2.3 Gear restrictions

Gillnet length was limited to 2.5km in 1986; bottom set gillnets were prohibited following observed interactions with turtles in the Fog Bay region in 1992. In the NT, gillnet mesh sizes are restricted to 15–25cm with a minimum twine diameter of 0.9mm, and longline lengths to 20nm (there are no restrictions on hook numbers) (Clarke 1996). In WA west of 123°45'E, gillnets are not permitted and longlines are limited to 500 hooks. On the Queensland east coast, there is a maximum gillnet length of 600m and mesh sizes must be between 11.5 and 2cm.

4.2.4 Vessel regulations

A maximum vessel size of 25m applies to the NT Fishery Joint Authority. Vessels larger than 25m that operated in the fishery prior to introduction of a maximum vessel size are able to continue in the fishery as a pre-existing operation. All commercial vessels must pass regular maritime surveys to operate.

4.2.5 Biological regulations

On the Queensland east coast, there is a closed season for net licences from 1 November to 1 February to protect barramundi. There are no specific size regulations but very large specimens are avoided because of their generally higher mercury levels. There is a uniform maximum permissible mercury level for fish in Australia of 0.1mg/kg. Four species of shark are protected in certain regions of the NSF. Whale sharks (Rhincodon typus) and white sharks (Carcharodon carcharias) are protected in WA, and white sharks, grey nurse shark (Carcharias taurus) and sand tiger shark (Odontaspis ferox) are protected in Queensland.

4.2.6 Effort allocation

Gear restrictions are applied uniformly to all operators within their respective management area.

4.3 Perspectives on management

4.3.1 Managers perspective

Although there are three separate Joint Authorities in the NSF the MOUs require that there are collaborative arrangements between the participants. So, while there are separate management advisory bodies in each State/Territory a meeting of, for example, the Queensland Fishery Advisory Committee would have NT industry members and would also invite participants from the other Joint Authority fisheries. While this process is still relatively new (The Queensland committee has only met once to date), it is generally seen as satisfactory.

4.3.2 Users perspective

The management advisory bodies set up subsequent to the OCS have given the industry greater involvement in the management process. However, there is a view among some fishers that the OCS has complicated fishing arrangements in the GoC, rather than making them simpler. Prior to OCS only one fishing permit was required for the GoC, while subsequently separate permits are required for the NT and Queensland zones.

4.4 Discussion

Sharks are particularly vulnerable to over-fishing because of their specialised life history and most targeted shark fisheries where there has been no regulation or management have been short-lived (Stevens et al. 1997). While the NSF is not as unified, or tightly regulated, as Australia's other target shark fisheries (the Southern Australian Shark Fishery and the Western Australian Temperate Shark Fishery), the management arrangements still provide an important means of ensuring the sustainability of the fishery. The management process involves industry, managers and researchers through the management committees.

5. RESOURCE ASSESSMENT

5.1 Provision of resource assessment advice

The level of quota for the foreign fishery was determined by a Northern Fisheries Committee Working Group. Initial assessments of the northern shark resource were made by the Northern Pelagic Fish Stock Research Programme (Anon 1990) and by Stevens and Davenport (1991). Subsequently a number of stock assessment workshops have been held the most recent of which was in July 1997. At this meeting, fishers from the NT and fisheries scientists from Queensland, NT, and WA Fisheries Divisions, Bureau of Resource Sciences, CSIRO, Sydney University and the University of British Columbia, Vancouver, developed assessments of stock structure, trends, and sustainable yields for shark.

5.2 Fisheries statistics

5.2.1 Methods used for collection of catch and effort data

i. Taiwanese fishery

Some pre-AFZ catch and effort data are available from the literature (Walter 1981; Liu 1985; Stevens and Davenport 1991). The three main sources of catch and effort data from 1979 are AFZ logbooks, radio reports and annual reports produced by the National Taiwan University.

ii. AFZ logbooks

In 1980, a logbook system was implemented by the Australian Department of Primary Industry to record data by individual set. The information recorded included logtype, boat code, date, net specifications, fishing times, water depth, total catch and catch components of the major commercial groups (shark, tuna and mackerel). Three log types were used: GN01, GN02 and GN04 (GN03 was not used). GN01 recorded effort as hours from the start of the set to the start of the haul. GN02 recorded effort as hours from the start of the set to the end of the haul. GN04 recorded effort as the number of sets, each record representing one set. The Taiwanese reported shark as processed weight. The department had intended that live weight be recorded; the mistake was not discovered until the logbook system had been in operation for some time. Figures for the total catch and for the components of the catch were recorded as weights on the GN01 and GN04 log-types. On the GN02 logs, while the total catch estimate was recorded as a weight, the catch components could be recorded as either weight or number. The logbook data were stored on the Australian Fisheries Zone Information System (AFZIS).

iii. Radio reports

The Taiwanese were also required to provide a radio report every six days giving their position and catch for the previous six days. Log-type (RR01), boat code, date, time (at which the report was sent), position (at the time of reporting), effort (as the number of sets), total catch (kg) and the catch breakdown (shark, tuna and mackerel) were reported. The catch information in the radio reports was expected to correspond with that in the logbooks. The radio report data were also stored on the AFZIS database.

iv. Taiwanese annual reports

Data from the logbooks kept independently by the Taiwanese are summarised in reports of the National Taiwan University (1980–1985). Catch and effort statistics are presented by half degree squares for 3 monthly periods between 1980 and 1985. Effort is expressed as 100pcs (panels) × 10h from 1980 to 1983 and as 1000pcs × h from 1984 to 1985. It is not clear whether the unit of time (hours) includes setting or hauling of the net.

v. AFZ observers

In addition to these main sources of catch and effort data, the Australian Fisheries Service placed observers on-board Taiwanese vessels, to collect information on net specifications, catch composition and catch weight. All these data were not collected from every boarding. Of the observer boardings, 40% were in the Arafura Sea; the remainder were from around the Wessels Islands and in the Timor Sea and North West Shelf. About 2% of the total gillnet sets were covered by the AFZ Observers.

vi. Domestic fishery

Licensed commercial fishers are required by law to supply catch and effort data to their relevant State or Territory fisheries agency. The format of the catch and effort data supplied varies by State/Territory and includes:

• fishing method
• amount of gear used (net length, mesh size, number of hooks)
• number of times the gear is set each day
• number of hours the gear is fishing
• number of days fished in each geographical block
• weight of each species (or category) by fishing method and block
• landing condition of each species (whole, trunks, fillets)

The NT and Queensland Fishery Joint Authorities, and the Queensland east coast fishery, collect these data through a logbook system. There are currently no logbooks in the WA northern shark fisheries but fishers are required to submit catch returns. The level of species breakdown varies between logbooks from a general category of shark (Queensland east coast fishery) to some degree of shark species identification in the NT logbook. Data are processed by the relevant fisheries agency and computerised.

5.2.2 Evaluation of the data collection process

i. Foreign fishery

To verify the catch and effort information and to determine which data set would be most suitable for analysis, Stevens and Davenport (1991) compared the different setsof catch data. Catch data from the AFZ logbooks and radio reports, and Taiwanese annual reports were examined by three monthly intervals and by year and there was reasonable agreement between the data sets. The reasons for disparities included mis-reporting of catch, confusion between the different versions of the AFZ logbook, errors in estimating and recording catch weight, and errors in transcribing the written logs to computer file. Stevens and Davenport (1991) also compared observer records and Taiwanese catch records (AFZ logbook entries) for a sub-set of the data. Although anecdotal information suggested that when observers were onboard, the Taiwanese often entered the observer's catch figures in the AFZ logbooks, they found good, rather than exact, agreement between Taiwanese and observer catch estimates.

ii. Domestic fishery

Currently the different States/Territory have different logbook or catch return systems which leads to some incompatibility in the data collected. The degree to which the catch data are split by species vary between agencies and in some areas meaningful effort data are not available. There are plans to have a standard logbook across the NSF Joint Authority area.

5.2.3 Data processing, storage and accessibility

i. Foreign fishery

Pre-AFZ catch and effort data are given by Walter (1981) and Liu (1985) and are summarised in Stevens and Davenport (1991). The Taiwanese logbook and radio report data were stored in the AFZIS database but as a result of changes to this system these data are now only available from back-up tapes. The observer data on catch composition, catch weight and gear specifications were stored on Macintosh discs and some of these may now be lost. Data from the logbooks kept independently by the Taiwanese are summarised in reports of the National Taiwan University (1980–85). Stevens and Davenport (1991) document the various sources of error in the catch and effort data and the processing of the data that was necessary before analysis could be carried out. They rejected 29% of catch/effort records (6969 out of 24 203 in the database) which did not meet certain accuracy criteria. The processed catch and effort data computer files were stored at CSIRO Division of Marine Research, Hobart, but some files were lost during changes to the computing facilities over the last 12 years. Existing files are accessible to authorised staff of relevant agencies.

ii. Domestic fishery

Catch and effort data from the logbook systems are stored on databases at the relevant State and Territory fishery agencies. The data are confidential and can only be used by authorised staff. The release of specific vessel information is only permitted with the approval of the licence owner and normally the confidentiality provisions contained in the acts require amalgamation of data so that the activities of individual fishers cannot be detected.

5.3 Stock assessment

5.3.1 Assessment process

To set quotas in the Taiwanese fishery, estimates of biomass in the fished area were based on the 1975 and 1976 Taiwanese catch, at rates of exploitation of 0.5 to 0.75. Gulland's (1971) equation 0.5 MBo was used to estimate a maximum sustainable yield (MSY). Because the calculations of MSY were biased conservatively in a number of areas, the quota was initially set somewhat higher.

Initial assessments of the northern shark resource used a modification of an age-structured yield-per-recruit model developed by Terry Walker (Marine and Freshwater Resources Institute, Queenscliff, Victoria 3225) for the Southern Australian Shark Fishery. The parameters required for the model are gillnet selectivities, age and growth, natural mortality, catchability, weight-length and fecundity. Population estimates were also calculated using a modification of the Peterson method for tag-recapture data. The method used in the most recent stock assessment workshop (July 1997) was to define spatial stock units through an analysis of historical catch patterns and to use an age-structured population model to reconstruct the historical effects of natural mortality, age selective fishing, growth, and recruitment on stock abundance (Walters and Buckworth 1997).

5.3.2 Measures of stock abundance

Catch-per-unit effort data derived from the catch and effort information supplied on the logbooks is used as the measure of stock abundance.

5.3.3 Biological advice review process

The current stock assessments involve fishery scientists from a number of Commonwealth and State/Territory institutes as well as highly regarded consultant fisheries scientist from overseas.

5.3.4 Biological management reference points

No biological management reference points are currently used in the NSF.

5.3.5 Sustainability of the resource

Crude assessments of the northern shark resource by the Northern Pelagic Fish Stock Research Programme (Anon 1990) suggested that:

• A comparison of yield per recruit over a range of gillnet mesh sizes (10–25cm) showed that the most efficient mesh size was 15cm, the size used by both the Taiwanese and Australians.

• Between 1980–84, the average annual Taiwanese fishing effort was 755 000km/hr. The model indicated that to achieve the equilibrium state (at which point the population is neither increasing nor decreasing) Taiwanese fishing effort should not have exceeded 280 000km/hr for C. tilstoni and 190 000km/hr for C. sorrah. In the period 1980–84, this would have resulted in catches of 1890t live weight of C. tilstoni and 535t of C. sorrah, which would have represented maximum sustainable catches at that time. The actual average annual catch between 1977–84 was 4022t and 1676t live weight of C. tilstoni and C. sorrah respectively.

• The estimated biomass of C. tilstoni in 1984 in a portion of the Taiwanese zone (35% of the area fished) was 14 750t live weight using a modification of the Peterson method for tag-recapture data. This represents a density of 100kg/km² which is much higher than the 57kg/km² density estimate (both species combined) obtained from the Taiwanese fishery using an age-structured model. It is also considerably higher than the combined species density estimate of 89kg/km² from the Australian fishery. Since catch per unit effort (CPUE) is four times higher in the Australian fishery than in the Taiwanese fishery, the population estimate for the Taiwanese zone based on tag-recapture data would appear to be too high (assuming differences in CPUE reflect differences in stock size).

• Between 1984–89, the average annual effort in the Australian fishery was 12 000km/hr. At this level of effort the model indicates that the populations of both shark species are under-exploited. This is supported by CPUE data from the fishery which rose from 16 kg/km.hr in 1984 to 45kg/km.hr in 1988. Population estimates from tagging for the period 1984–87 varied from 6300 – 10 000t of C. tilstoni and 5200 – 10 000t live weight of C. sorrah. This suggests that the maximum sustainable catch for both species combined fromthe inshore Australian zone should be about 1500t. The actual catch (both species combined) has rarely exceeded 1000t.

More recently, the July 1997 stock assessment workshop concluded (Walters and Buckworth 1997)that:

• The stocks have already been heavily exploited and have been reduced to near or below optimum levels for long term production. There were considered to be disturbing indications of continuing stock decline in recent years, in spite of elimination of the legal foreign fishing that was mainly responsible for the initial decline. The MSY for blacktip sharks is likely to be at least 2000t/yr for the NT, Queensland, and WA Fishery Joint Authorities combined, but it is unclear whether this total is now being exceeded due to illegal or transboundary fishing.

• CPUE statistics corrected for shark targeting (square root variation in CPUE with stock size) suggest that the Taiwanese fishery reduced the NT/Arafura component of the stock by about 60–70%. The Gulf stock component probably did not decrease by more than 30% during this period.

• Age-structure modelling indicates that the overall stock (NT/Arafura plus Gulf components) should have been increasing at a rate of between 5% and 10% per year since the mid-1980s when Taiwanese catches were greatly reduced, in spite of more recent domestic catches. However, CPUE data from the NT gillnet fishery indicate a substantial decline in relative abundance since the mid-1980s. This suggests unreported catches of about 1500t/yr from the stock compared to the average reported catch of 300t/yr by all domestic fisheries combined.

• Another possibility is that declines in domestic CPUE have been due to slow depletion of the inshore, resident component of the stock but that recent fishing has not had a major impact on the stock as a whole. The tagging data, which show relatively low mixing rates, are not totally inconsistent with this hypothesis. However, if this is the case, this stock component has a much lower sustainable yield than would be estimated for the stock as a whole based on the offshore Taiwanese removals.

5.4 Perspectives on resource assessment advice

5.4.1 Managers perspective

The stock assessment process apparently works satisfactorily despite a number of different agencies being involved with each maintaining their own catch and effort systems. The assessment workshops involve the industry in t he process and consider all the issues with outcomes being explained to the fishers. An experienced overseas fisheries scientist and resource modeller has been involved with the recent assessment workshops. Managers, researchers and surveillance personnel from WA, NT, Queensland and the Commonwealth meet on an ‘as needed’ basis, but at least once a year, to consider matters of joint interest.

5.4.2 Users perspective

No fishers have been questioned directly about their views on the resource assessments in compiling this report. However, there is apparently general agreement among fishers on the assessment advice provided.

5.5 Discussion

The report from the July 1997 workshop notes that the assessment process had to rely almost entirely on highly suspect CPUE statistics from both the Taiwanese and domestic gillnet fisheries. It is suspected that neither of these fisheries has provided CPUE trends proportional to changes in the actual stock size, and there is little prospect that future information from logbook programmes will be more useful. A key recommendation from the latest assessment is to establish a co-operative programme with fishermen to provide a ‘fishery independent’ index of stock trend based on standardised, regular fishing at a set of consistent test locations along the NT coast and into the Gulfs. There should also be a concerted effort to obtain blacktip catch statistics from the foreign fisheries currently operating in the Arafura north of the AFZ, for comparison to the estimate of 1500t/yr unaccounted removal from the stock (Walters and Buckworth 1997).

6. LAW AND ENFORCEMENT

6.1 Legal status

Management of the NSF currently includes three separate Joint Authorities which are controlled by a number of MOUs established under the OCS. Legislation of the MOUs is empowered under:

• the Fisheries Act 1994 (Queensland)
• the Fisheries Act 1988 (Northern Territory)
• the Fish Resources Management Act 1994 (Western Australia)
• the Fisheries Management Act 1991 (Commonwealth)

Fishers need a valid fishing license for the relevant section of the fishery. These fisheries are limited entry (with the exception of the Queensland east coast net licence) and no new licences are issued.

6.2 Enforcement problems

Enforcement problems include:

• fishing without a licence
• illegal fishing gear (incorrect mesh size or exceeding permitted net length or number of hooks).
• fishing in closed waters

Enforcement problems in the domestic fishery are reported to be relatively minor. There are some concerns over illegal foreign fishing inside the AFZ as it appears to be increasing.

6.3 Surveillance and compliance

Surveillance and compliance in the NSF is the responsibility of fisheries officers employed under the Commonwealth/State/Territory fisheries acts. In the NT for example, it is carried out by the Marine and Fisheries Enforcement Unit of the NT Police, Fire and Emergency Services, as part of their fisheries tasks (Clarke 1996). Fisheries officers check for illegal fishing activities and check that gear and vessels conform to legislative and regulatory specifications. The majority of surveillance is carried out on shore but there is also aerial and patrol vessel surveillance. In the NT, there are only two main unloading sites which makes surveillance easier. There is some degree of self-regulation in that licensed fishers generally know where certain vessels should be operating and may report violations to fisheries officers.

6.4 The legal process

Fisheries officers are responsible for issuing infringement notices for offences under the relevant fisheries acts. Penalties are specified in the fisheries acts and imposed by the courts. Most penalties are of a monetary nature but in certain cases the acts allow for seizure of catch, gear and vessels, loss of licence and even gaol sentences.

7. MANAGEMENT SUCCESS

7.1 Profitability of the fishery

No economic surveys of the NSF have been carried out. The fishery is relatively diverse and comprises full and part-time operators, vessels ranging from 6–35m nd crew from 2–10 per vessel. The main operators are continuing in the fishery and there is still interest in obtaining licences which suggests that participating in the NSF is profitable, at least for some operators.

7.2 Issues of equity and efficiency

Since there are a large number of part-time vessels with low catch rates the fishery is clearly not operating at maximum efficiency. A significant reduction is vessel numbers would almost certainly improve the efficiency of remaining fishers but such measures have obvious social implications. Management objectives of the fishery are required to address both economic and social issues.

8. MANAGEMENT COSTS

Management costs of the NSF are not available; there is currently only partial recovery of management costs through licence fees. In WA, there has been a move since 1995 towards full cost-recovery in the larger, high revenue fisheries but whether this will extend to smaller fisheries such as shark is not certain. Full recovery of costs would include research, licensing, policy setting and compliance monitoring (Simpfendorfer 1997). The NT has decided not to pursue full cost-recovery While Queensland's cost-recovery principles are intermediate between those of the NT and the full cost-recovery model of WA.

The fishery is of relatively low priority to the Commonwealth and States/Territory involved in it and current research costs ar mainly associated with the periodic stock assessment workshops. during the 1980s, research costs of the Northern Pelagic Fish Stock Research Programme were about A$537 000 with the majority of costs met by two grants from the Fishing Industry Research Trust Account.

9 ACKNOWLEDGEMENTS

I am grateful to Rik Buckworth and Ray Clarke (Departmetn of Primary Industry and Fisheries, Northern Territory). David Wilkinson (Queensland Fisheries Management Authority), Neil Gribble (Queensland Department of Primary Industries), colin Simpfendorfer and Jo Kennedy (Fisheries Western Australia) and Kevin McLoughlin (Bureau of Resource Sciences) for information and time spent talking about the NSF.

10. LITERATURE CITED

Anon 1990. Northern Pelagic Fish Stock Research. Final report to FIRDC projects 83/49 & 86/87, 325 pp.

Anon 1991–1997. Australian Fisheries Statistics. Australian Bureau of Agriculltural and Resource Economics, Canberra.

Caton, A., McLoughlin, K.J. and d. Staples 1977. fishery Status Reports. Resource assessments of Australian Commonwealth fisheries. Bureau of Resource Sicences, Canberra, 139 pp.

Clarke, R. 1996. Northern Shark status report 1996. Department of Primary Industry and fisheries, Darwin, 5pp.

Davenport, S.R. and J.D. Stevens 1988. Age and growth of two commercially important carcharhinid sharks from northern Australia. Australian Journal of Marine and Freshwater Research, 39, 417–33.

Gulland, J.A. 1971. Science and fishery managment. Journal du Conseil International pour L'Exploration d e la mer 33(3), 471–477.

Kailola, P.J., Williams, M.J., Stewart, P.C., Reichelt, R.E. McNee, A. and C. Grieve 1993. Australian Fisheries Resources. Bureau of Resources Sciences and the Fisheries Research and Development corporation, Canberra, 422 pp.

Last, P.R. and J.D. Stevens 1994. Sharks and rays of Australia. CSIRO, Australia. 513 pp + 84 colour plates.

Lavery, S. and J.B. Shacklee 1989. Population genetics of two tropical sharks, Carcharhinus tilstoni and C. sorrah, in lnorthern Australia. Australian Journal of Marine and Freshwater Research, 40, 41–57.

Lavery, S. and J.B. Shacklee 1991. Genetic evidence for separation of two sharks, Carcharhinus limbatus and C. tilstoni, from northern Australia. Marine Biolody 108, 1–4.

Liu, H. 1985. The status of Taiwanese gill-netter fishery in the waters off northern Australia. Unpublished report, 9 pp.

Lyle, J.M. 1984a. Mercury concentrations in four carcharhinid and three hammerhead sharks from coastal waters of the Northern Territory. Australian Journal of Marine and Freshwater Research, 35, 441–451.

Lyle, J.M. 1984b. North Australia's multi-species shark fishery. Volume 2. Mercury in shark from northern Territory waters. Department of Primary Production, Northern Territory, fishery Report No. 12, 51pp.

Lyle, J.M. 1986. Mercury and selenium concentrations in sharks from northern Australia waters Australian Journal of Marine and Freshwater Research. 37, 309–21.

Lyle, J.M. 1987, Observation on the biology of Carchariunus cautus Whitley). C melanopterus (Quoy & Gaimard) and C. fitzroyensis (Whitley) from northern Australia. Australian Journal of Marine and Freshwater Research, 38, 701–10.

McLoughlin, K.J. and J.D. Stevens 1994. Gill-net mesh slectives for two species of commercial carcharhinid shark taken in northern Australia. Australian Journal of Marine and Freshwater Researche, 45, 521–534.

McLoughlin, K.J., Staples, D. and M. Maliel 1993. Fishery Status Reports. Resource assessments of Australian Commonwealth fisheries. Bureau of Resource Sciences. Canberra, 135 pp.

McLoughlin, K.J., Staples, D. and M. Maliel 1994. Fishery Status Reports. Resource assessments of Australian Commonwealth fisheries. Bureau of Resource Sciences. Canberra, 144 pp.

Millington, P and D. Walter 1981 Prospects for Australian fishermen in northern gill-net fishery. Australian Fisheries 40 (9), 3–8.

Pender, P.J. Willing, R.S. and D.C. Ramm 1992. Northern prawn fishery bycatch study: Distribution, abundance, size and use of bycatch from the N.T. mixed species fishery. Department of Primary Industry and Fisheries, Fishery Report, 26, 70 pp.

Penn, J.W. 1997. State of the Fisheries Report 1996–1997. Fisheries Department of Western Australia, 142 pp.

Simpfendorfer, C.A. 1997. Management of shark fisheries in Western Australia. Report for the Food and Agriculture Organisation, Rome, 33pp.

Stevens, J.D. and S. Davenport 1991. Analysis of catch data from the Taiwanese gill-net fishery off northern Australia: 1979–1986. SCIRO Marine Laboratories Divisional Report 213, 51 pp.

Stevens, J.D. and P.D. Willey 1986. The biology of two commercially important carcharhinid sharks from northern Australia: Australian Journal of Marine and Freshwater Research, 37, 671–88.

Stevens, J.D. and J.M. Lyle 1989. The biology of three hammerhead sharks (Eusphyra blochii, Sphyrna mokarran and Sphyrna lewini) from northern Australia. Australian Journal of Marine and Freshwater Research, 40 (2), 129–46.

Stevens, J.D. and K.J. McLoughlin 1991. distribution, size and sex composition, reproductive biology and diet of sharks from northern Australia. Australian Journal of Marine and Freshwater Research, 42, 151–199.

Stevens, J.D., Walker, T.I. and C.A. Simpfendorfer 1997. Are southern Australian shark fisheries sustainable? In: Developing and sustaining World Fishery resources (D.A. Hancock, D.C. Smith, A. Grant, and J.P. Beumer, eds.) 62–66 pp, SCSIRO, Melbourne.

Walter, D.G. 1981. Some historical aspects of Taiwanese gill-netting off northern Australia. In: Northern Pelagic Fish Seminar. Eds. Grant, C.J., and Walter, D.G. Australian Government Publishing Service, Canberra.

Walters, C.J. and R. buckworth 1998. Assessment of spanish mackerel and blacktip shark stocks in the Northern Territory. Department of Primary Industry and fisheries. Unpublished Northern Territory Fisheries Report.

Welsford, J., Summer, J.L., Pyne, R.R. and J. M. Lyle 1984. North Australia's multi-species shark fishery. Volume 3. Consumer acceptability of shark. Department of Primary Production, Northern Territory, Fishery Report No. 12, 42 pp.

Williams, L.E. 1997. Queensland's Fisheries Resources. Current condition and recent trendds 1988– 1995. Department of Primary Industry, Brisbane, 101 pp.