QUEENSLAND MUD CRAB FISHERY

Transcription

1 ECOLOGICAL ASSESSMENT QUEENSLAND MUD CRAB FISHERY Compiled by Shannon Ryan, Queensland Fisheries Service January 2003 With assistance from Mark Doohan, Malcolm Dunning, Sue Helmke, Clare Bullock, Eddie Jebreen, Brad Zeller, Lew Williams, Jim Higgs and Kadesh Clarke, Queensland Fisheries Service and Ian Brown, Neil Gribble, Wayne Sumpton, Steve Bailey and Stirling Peverell, Agency for Food and Fibre Sciences

2 The Department of Primary Industries Queensland has prepared this report for Environment Australia for assessment under guidelines for exemption from export controls of the Environment Protection and Biodiversity Conservation Act 1999 relating to wildlife. INTRODUCTION The target species of the Queensland Mud Crab Fishery is Scylla serrata, a portunid crab variously known as mud crab, green mud crab, mangrove crab and black crab. Estuarine crabs of the genus Scylla inhabit most areas of mangrove-lined coastal habitat throughout the tropical and sub-tropical Indo-West Pacific (IWP) region. A taxonomic revision of Scylla by Keenan et al. (1998) identified four distinct species in the genus Scylla. S. paramamosain and S. tranquebarica are not found in Australian waters. S. olivacea, the brown mud crab, is found within Queensland waters in the northern part of the Gulf of Carpentaria, however the species requires low salinity estuarine habitats and therefore both its distribution and abundance is limited. S. olivacea rarely grows to the minimum legal size of 15cm carapace width (CW; carapace width is measured laterally across the carapace, between the first [most external] spine on either side). Given these factors, commercial, recreational and indigenous fishers rarely harvest S. olivacea. All references to mud crab throughout this report refer to the primary component of the catch, S. serrata. Distribution S. serrata is widely distributed throughout the IWP, from Japan across the Asian subcontinent to northern Australia, and from the east coast of Africa across to Tahiti. In Australia, mud crabs are found from Shark Bay in Western Australia, along the northern coastline and south to northern New South Wales. The entire Queensland coastline, both the along east coast and in the Gulf, is inhabited by S. serrata. Recent genetic research by David Gopurenko, a PhD candidate at Griffith University in Brisbane, is shedding new light on regional patterns of genetic structure among Australian mud crab populations. Based on investigations of the mitochondrial DNA signatures of S. serrata, Gopurenko et al. (1999) and Gopurenko and Hughes (2002) have identified two clades of S. serrata within Australian populations of the species. A clade is generally defined as a reproductively distinct group within which all individuals are derived from a common ancestor. The two clades appear to be geographically separated either side of the Torres Strait: one clade is distributed westward from the Torres Strait along the northern Australian coastline; the other clade is distributed along the eastern Australian coastline. Fishery Area The Queensland mud crab fishery occurs in all waters adjacent to the State of Queensland, including the waters of the east coast of Queensland and waters of the Gulf of Carpentaria (Map 1). As of April 1999, waters of the Torres Strait were excluded from Queensland jurisdiction and managed collectively, by the Commonwealth, the State of Queensland and Torres Strait Island Communities through the Protected Zone Joint Authority. In the Gladstone region, Eurimbula Creek (north of Round Hill Creek) and all adjoining waterways are closed to the harvesting of mud crabs. Additionally, some areas of the fishery are subject to closures to fishing 2

3 through marine park zoning established under the Commonwealth Great Barrier Reef Marine Park Act 1975 and the Queensland Marine Parks Act Map 1. Boundary of the Queensland mud crab fishery. 3

4 Biology and Ecology The information contained in this section is sourced from Gribble, Brown and Williams (2002). Mature crabs mate when the female is in the soft-shell condition, which is about 48 hours after moulting. The female may remain under the protection of the male, usually in the shelter of burrows, for several days until her new shell has become hard. Sperm is stored until the eggs are extruded, and can remain viable for up to seven months. Multiple spawning in the one season may follow a single mating, and each egg mass may contain from two to eight million eggs, depending upon the size of the female. Embryonic development within the egg takes from two to four weeks, depending on water temperature. Egg-bearing females are rarely seen as they migrate to deep waters offshore to spawn. After hatching, the larvae progress through four pelagic stages during the next two weeks, drift inshore via currents, and transform into a semi-pelagic state before settling onto suitable substrate in shallow water. After 5 12 days they metamorphose into juvenile crabs. As with other crustaceans, growth occurs through moulting. This involves the shedding of the hard shell, and then swelling of soft body tissues to expand the new soft shell before it hardens. In Moreton Bay, mud crabs grow to 8 10 cm carapace width (CW) in their first year, cm CW in their second year and (potentially) 24 cm in their third year. This growth rate appears to be accelerated in warmer northern and Gulf waters. Growth is seasonal, with moulting activity mainly from September to January. Brown (1993), summarised a number of studies on mud crab growth and sexual maturity from a variety of latitudes, and found a considerable degree of variation in both age and size at which mud crabs reach maturity. Sexual maturity has been observed to occur between months and cm in tropical latitides (e.g. Philippines, Malaysia, PNG) while in sub-tropical latitudes such as south-east Queensland maturity has been estimated to occur at approximately 13.8cm and up to 27 months (Heasmann 1980). Mud crabs live for up to 3 4 years and can reach a CW of 24 cm. Mud crabs are omnivorous scavengers and are cannibalistic, eating other crabs, barnacles, bivalve molluscs and moribund or dead fish. The larger claw is often used for crushing shellfish such as mussels, whereas the other is used for biting, cutting and manipulating the food. Mud crabs usually remain in the protection of burrows during the day and feed at night, in the early evening and just before dawn. Juveniles and adults use the same habitat within sheltered estuaries, the tidal reaches of mangrovelined rivers and streams, mud flats and mangrove forests. Strengths in the mud-crab life cycle that give high resilience to fishing pressure, include very high fecundity, protracted spawning period, rapid growth and early sexual maturation. Weaknesses of the life cycle include dependence of juveniles upon the availability and quality of appropriate near-shore habitat and the requirement for significant spawning migration by egg-bearing females, potentially increasing vulnerability to fishing activity. 4

5 Fishing Gear and Methods Crab pots and collapsible traps are the main fishing apparatus used by commercial fishers to take mud crabs. Recreational fishers use similar apparatus to commercial fishers but are also permitted to use dillies. Under the Fisheries Regulation 1995: A crab pot defined as a fishing apparatus comprising a cage with a round opening in the top, or an elongated opening (parallel to the base) in the side ; A collapsible trap is defined as a trap made of rigid material, with 1 or more collapsible sides ; A dilly is a fishing apparatus comprising a frame and a net that hangs below the frame s horizontal plane when the apparatus is in use ; and An inverted dilly is defined as a fishing apparatus comprising a frame and a net with a float attached so the net is above the frame s horizontal plane when the apparatus is in use. The steel mesh/wire pots common up until the late 1980 s are gradually being replaced in both the commercial and recreational fisheries by more collapsible apparatus. The three pots illustrated below (Figure 1) are those commonly used by commercial and recreational fishers. The size and shape of the pots vary, though most have two entrance funnels and are cylindrical in shape. An example of the dillies commonly used by recreational mud crab fishers is also provided (Figure 1, bottom right). Figure 1. The various apparatus used by commercial and recreational fishers in the Queensland mud crab fishery. When fishing for mud crabs the general idea is to entice the mud crabs into the pots, traps or dillies by placing bait inside the apparatus. The most common baits used include fish and fish frames, however other meat and bones are also used. Both 5

6 commercial and recreational mud crab fishers employ a similar technique when fishing with pots or traps. Pots are set on the substrate, generally in estuarine or nearshore coastal areas, and are checked daily or on each rising tide. The pots are hauled by hand to a dinghy or small boat, checked for mud crabs, rebaited, and then reset. When checking for mud crabs, the management arrangements for the Queensland mud crab fishery require that all undersize and female mud crabs are immediately returned to the water at the point of capture. Recreational fishers using dillies lower the baited dilly to the substrate, mud crabs crawl into the net after the bait, then the whole net is lifted up, the crab is removed, and the net is again lowered into the water for another capture. The Commercial Fishery To engage in commercial harvesting in Queensland a person must hold a Queensland Master Fisher s Licence and the vessel from which the operation is undertaken must be licensed as a Queensland Primary Commercial Fishing Vessel (CFV) with the licence endorsed to operate in the particular fishery. In the mud crab fishery, the required symbol is known as a C1 symbol. There are currently 794 vessels with a C1 symbol to take crabs. However, less than two-thirds of those vessels actually harvested mud crabs during 2001 (see Table 1). Limited entry arrangements commenced in 1984 for the mud crab fishery. Under the limited entry arrangements no new vessel licences are being issued. The only way to enter the fishery for a commercial purpose is to acquire an existing licensed vessel and engage a Master Fisher to operate it. All commercial fishers in Queensland have a legal obligation to provide information about their fishing activity through the use of compulsory daily logbooks. This information is compiled in QFS CFISH system - the Commercial Fisheries Information System, which commenced in It is important to recognise that the accuracy and reliability of data from the first year of the program (1988) may be uncertain due to teething problems in launching CFISH. For the mud crab fishery, the data commercial fishers provide to CFISH via the logbook program must include a daily record of the location fished, an estimate of mud crab caught (in kg), an estimate of other crab species caught (excepting spanner crab which is prohibited), the total number of pots used, the total number of pot lifts, and any interactions with threatened or protected species (Gribble, Brown & Williams 2002). The reporting of interactions with threatened or protected species is currently being enhanced through an amended logbook. A summary of annual statistics for the Queensland mud crab fishery is provided in Table 1. Statewide, the numbers of boats reporting harvest has oscillated significantly, though a general upward trend is apparent. The days fished per boat exhibits a similar pattern some oscillation with a general upward trend. Accordingly, the total effort of the commercial sector, measured as total boat days fished, has increased though the trend has been variable. Total effort increased significantly during the periods and However, over the past two years (2001 and 2002) total effort has again decreased such that the 2002 total effort was back to the 1999 level. Commercial harvest trends have been generally upward with the highest reported catch of about 1000 tonnes in The current total catch (2002) is approximately 6

7 equivalent to the 1999 total catch. Mean annual CPUE, measured as daily boat harvest (kg/day), averaged about 21 kg with no substantial upward or downward trend, although there is some variation. The period was below the mean daily catch rate, while the year 1990 and the period were above the mean. The top 10% of the fleet, about 50 boats, landed 50% of the harvest and applied 35% of the effort in terms of days fished. These boats typically worked for 160 days per year with a daily harvest of about 30kg. Table 1. Annual statistics for the Queensland mud crab fishery Year Boats Catch (t) Days fished Days/boat Kg/day The aggregated statewide data can also be analysed at a finer spatial scale. Williams (2002) divided the Queensland coastline into eight regions, to allow regional analysis of CFISH data (see Map 2). Although mud crabs are harvested from estuaries along the entire Queensland coast, approximately 70% of the catch is harvested from three regions. Based on 2001 data, the Capricorn region accounts for approximately 42% of the total catch, the Gulf region approximately 16%, and the Northern Dry region approximately 12% (see Table 2). Table 2. Breakdown of catch data for the eight CFISH regions (based on the 2001 fishing season). Location Catch (t) Proportion of Catch (%) Gulf Remote Northern Wet Northern Dry Swains Capricorn Fraser Burnett Moreton State total 987 7

8 Map 2. The eight CFISH regions based on Williams (2002) The Recreational Fishery Mud crabs are also a popular target species for recreational fishers. QFS undertakes a biennial estimate of the recreational catch of mud crab in Queensland through telephone and diary surveys conducted under RFISH the Recreational Fishing Information System. RFISH surveys have been conducted in 1997, 1999 and The 1997 RFISH survey estimated that approximately mud crabs were harvested by recreational fishers in that year. The 1999 RFISH survey estimated that approximately one million mud crabs were harvested while a further 2.5 million mud crabs were caught and released. The average mud crab weight of the recreational harvest has not yet been estimated however Gribble, Williams and Brown (2002) suggest that the commercial average weight of 1kg per crab can be used without 8

9 significant error since the same size restrictions apply to both commercial and recreational fishers. Accordingly, the recreational harvest of mud crabs throughout Queensland is estimated at tonnes in 1997 and tonnes in Gribble, Williams and Brown (2002, p126) state that the recreational catch was distributed along the eastern coast of Queensland with similar regional patterns to those of the commercial sector, apart from the Moreton region. It is estimated that the Moreton region recreational harvest was about 260 tonnes in 1997 and The Indigenous Fishery The catch of mud crabs in Queensland by indigenous fishers and communities in north Queensland is currently being estimated as part of the National Recreational and Indigenous Fishing Survey (NRIFS) funded by the Fisheries Research and Development Corporation (FRDC) and the Natural Heritage Trust (NHT)(Johns 2000). The results will be available with the release of the final NRIFS report in midto late-2003 (J. Higgs, QFS, pers. comm., 2003). Historical Management of the Fishery Crabs comprised an important dietary component for aboriginal communities along the Queensland coast before and after European habitation. The earliest records of European involvement in the crab fishery date back to the establishment of the penal settlement on the shores of Moreton Bay in the 1820 s. Convicts caught crabs along with other marine animals to supplement food production in the settlement. The subsistence harvesting of crabs soon developed into small-scale commercial operations during the latter part of the 19 th century, first in Moreton Bay and then beyond, to cater for the needs of Queensland s expanding population. By the turn of the century a recognised crab fishery had emerged. A range of management measures has evolved over the life of the mud crab fishery to provide restraints on fishing effort and to ensure sustainable management of the mud crab resource and its habitat. A timeline of the history of the fishery and the management arrangements introduced is provided in Table 3. Table 3. Queensland mud crab fishery: history and management arrangements. Time Frame Historical Management Pre-European Aboriginal communities harvested mud crabs for subsistence needs. settlement 1820 s Convicts caught crabs on the shores of Moreton Bay along with other marine animals to supplement food production. Late 1800 s 1890 s Early 1900 s Small-scale commercial operations were established to cater for the needs of Queensland s expanding population. Growth extended beyond Moreton Bay to population centres along the coast. Minimum weight restrictions were introduced: 3 pounds (~ 1.4 kg) for male mud crabs and 10 pounds (~ 4.5 kg) for female mud crabs. A recognised mud crab fishery emerged. 9

10 1913 Harvesting female mud crabs was prohibited (this restriction continues to apply). The minimum weight restriction for male mud crabs was converted to a minimum size limitation: 5 inches (12.5cm) carapace width (CW) The minimum size for male mud crabs was increased to 6 inches (15cm) CW (this restriction continues to apply) Where the carapace of a crab is damaged alternative underside measurements must be used: 4.6cm from joint of the claw to the joint of the last walking leg (this restriction continues to apply). The possession of crab meat and claws separate from carapace was prohibited 1984 Limited entry arrangements were introduced into the commercial mud crab fishery. Gear and in possession limits were implemented in the recreational fishery: a maximum of four apparatus and an in possession limit of 10 legal size male crabs A limit of fifty crab pots was introduced for each commercial fishing operation. Previously this limit applied to each licensed master fisherman involved in the operation (this restriction continues to apply). Current Management Arrangements The Queensland Fisheries Service (QFS) in the Queensland Department of Primary Industries (QDPI) is responsible for managing the Queensland mud crab fishery. Queensland Boating and Fisheries Patrol, a part of QFS, undertakes compliance and enforcement. Research and monitoring of the fishery is conducted jointly by QFS and QDPI s Agency for Food and Fibre Sciences (AFFS). QFS manages the mud crab fishery under the Fisheries Act 1994 (the Act) and the Fisheries Regulation Some areas of the fishery are also subject to marine park zoning established under the Commonwealth Great Barrier Reef Marine Park Act 1975 and the Queensland Marine Parks Act As outlined in the previous section, a number of input and output controls have been developed over the history of the fishery to ensure it is sustainably managed over the long-term. A complete list of the current management controls in place in the fishery is provided in Table 4. If threats to the sustainability of the fishery are identified, QFS has various mechanisms available under the Act to respond in a timely manner. These include the power to: a) declare a closed season, closed waters or closed species (section 43 of the Act); b) declare quota (section 44); c) make an emergency fisheries declaration (section 46) where urgent action is needed to meet a significant threat to fisheries resources or habitat; d) refuse to issue or renew an authority (section 59) where it is necessary or desirable for the best management or protection of fisheries resources; e) impose conditions on issue or renewal of an authority (section 61); f) amend an authority (section 63); and g) suspend or cancel an authority (section 67) where it is necessary or desirable for the best management, use, development or protection of fisheries resources or fish habitats. 10

11 Table 4. Summary of the current management arrangements for mud crabs Management arrangement Commercial fishery Recreational fishery Number of Fishers Limited Entry Unlimited Taking female crabs Prohibited Prohibited Minimum size limit 15cm carapace width 15cm carapace width In possession limit N/A Not more than 10 per person No. of apparatus Not more than 50 per Not more than 4 per crab fishery symbol Apparatus marking Owner s name or primary commercial fishing boat marking Float marking Owner s primary commercial fishing boat marking person Owner s surname and address Owner s address Float size 15cm in any dimension 15cm in any dimension Age limit on using crab N/A Must be 15 yrs or over apparatus Use of crab hooks Prohibited Prohibited Possession of crab meat Prohibited Prohibited Possession of crab claws separate from body Prohibited Prohibited A range of enforcement and compliance measures are in place in the fishery. One aspect of compliance in the fishery concerns the compulsory return of daily logbook information. For non-quota fisheries such as the mud crab fishery, the daily logbook records must be returned to QFS on a monthly basis. If a fisher does not return the logbook data, the following steps are followed: a reminder letter is sent requesting the logbook, and also reminding the fisher of the compulsory logbook requirement; approximately one month later a show cause letter is sent. The letter again requests the logbook and also asks the fisher to show cause why the noncompliance should not result in suspension of the fisher s license for that fishery. if the logbook is still not forwarded, the fisher s licence for the fishery may be suspended until the logbook is provided. The Fisheries Act 1994 ( the Act ) defines an offence against fisheries legislation prescribed under a regulation or Management Plan to be a serious fisheries offence. In effect, the Act enables offence types common to many fisheries to be covered by regulation, and significant offences may be addressed within a management plan for that fishery. Section 108 of the Fisheries Regulation 1995 establishes serious fisheries offences as: Forfeiture offences for which an inspector may seize fisheries resources in a heap (for example, fish in a processing establishment where, because of the quantity of fish, it is impracticable to count the fish of a particular species or type); Offences against fisheries regulation that involve: - contravening a closed season or closed-water declaration; 11

12 - buying or selling fish; - obstructing, hindering or resisting an inspector; and - using or possessing illegal fishing apparatus. A serious offence can have several consequences. The most obvious is in the penalties applied to offenders. Magistrates have full discretion in setting penalties for fisheries offences up to a maximum level for each offence. If an offence is identified as serious, then it is likely that a higher-level fine would be applied. The management arrangements for the mud crab fishery have been developed over several years through a formal and statutory public consultative process involving a Management Advisory Committee, CrabMAC, and public comment and input. The Management Advisory Committee provides advice and recommendations on the appropriate management arrangements to ensure the sustainable use of the mud crab resource. CrabMAC includes representatives with a range of expertise and representing broad community interests. The stakeholders currently represented on CrabMAC are listed in Table 5. It should be noted that the conservation member position is currently vacant, though it has been filled previously. QFS has approached environmental organisations to fill the position however these efforts have been unsuccessful to date. Table 5. Current CrabMAC stakeholder membership Stakeholder Interest DPI Appointed Chair Research Member (QDPI AFFS) Recreational Fisher QFS Fishery Manager Qld Boating & Fisheries Patrol (QBFP) Commercial Fisher Commercial fisher Recreational fisher Seafood Marketing Commercial Fisher Great Barrier Reef Marine Park Authority (GBRMPA) In 1999, the then fishery management agency, the Queensland Fisheries Management Authority (QFMA), released the Discussion Paper - Queensland Mud Crab Fishery (QFMA 1999) seeking public comment and input on an extensive range of issues facing the fishery (see Appendix 3 for a complete list of the issues raised for public comment). Primary among these issues was the separation of the Gulf and the East Coast mud crab fisheries. The Discussion Paper sought comment on the development of separate fishing symbols, management arrangements and management plans for the Gulf and the East Coast. Previous to the Discussion Paper, QFS, with the full support of CrabMAC, had indicated its intent to develop separate management arrangements for the Gulf through the 1997 Investment Warning for the Gulf of Carpentaria Mud Crab Fishery (QFMA 1999). The investment warning advised all interested parties that investment and catches after the date of [the] warning [were] extremely unlikely to be recognised in determining eligibilities for future participation in the [Gulf] fishery (QFS media release, cited in QFMA 1999). 12

13 The release of the Discussion Paper was the first step in developing a formal Management Plan for the fishery. QFMA distributed approximately 2800 copies of the Discussion Paper to stakeholders and groups directly and indirectly involved in the fishery. A significant level of public response was received, comprised of: 24 responses from organisations/groups/branches; 82 responses from commercial fishers; 123 responses from recreational fishers; 1 response from an indigenous fisher; and, 9 responses from other stakeholders. QFMA collated and analysed the responses. CrabMAC also analysed the responses and provided comments and recommendations. The development of the Mud Crab Fishery Management Plan is awaiting the implementation of management plans currently in-progress for other fisheries (Mark Doohan, Fishery Manager, QFS, pers. comm., 2003). Environmental Impacts of the Fishery At current levels of effort, utilising current fishing gear and methods, and under current management arrangements, QFS considers the Queensland mud crab fishery does not pose any significant threat to dependent and associated species; endangered, threatened or protected species; or the broader marine ecosystem generally. Mud crab pots are generally constructed of wire mesh though hard plastic and trawl mesh pots are also used in the recreational fishery, as are mesh dillies (see Figure 1). These apparatus are relatively lightweight and stable and therefore impart little physical impact to the muddy substrates of the estuaries or foreshore areas in which they are set. Daily pot checks and frequent pot repositioning, which is the standard practice in both the commercial and recreational fisheries, further reduces the potential for long-term impacts to benthic habitats and communities, or to water quality in general. Mud crab pots are also a non-destructive fishing apparatus as they function by trapping; crabs are enticed into the pots with bait and their escape is restricted. Considered in combination with the general practice of daily pot checking, mud crab pots impart little physical damage to either mud crabs or any bycatch that is caught. This is an important factor as it results in high survivability in undersize and female mud crabs, and bycatch species, that are released. All available evidence suggests that the take of non-target bycatch species in the Queensland mud crab fishery is minimal. Preliminary results on non-target catch obtained by QFS through fishery-independent surveys conducted in the Long-Term Monitoring Program indicate an average non-target CPUE of approximately one individual every three to four pot lifts (Sue Helmke, QFS, pers. comm. 2002). The preliminary bycatch results obtained in the NTDBIRD-FRDC-QDPI Mud Crab Project support these general observations (Steve Bailey, AFFS pers. comm. 2002). Anecdotal evidence from researchers and fishers in both Queensland and the Northern Territory confirms that minimal non-target catch is taken. 13

14 Concerning byproduct from the mud crab fishery, very little of the non-target catch that is taken is considered useful or desirable as byproduct. Comments from QDPI researchers with experience in the mud crab fishery indicate that commercial fishers opportunistically use some larger fish, particularly cod and catfish, as bait for crab pots (Steve Bailey, AFFS, pers. comm., 2002; Stirling Peverell, QFS, pers. comm., 2002). Mud crab fishers may legally retain blue swimmer crabs for sale as byproduct. However, the byproduct catch of blue swimmer crabs is not considered a significant risk to populations of that species since mud crabs and blue swimmer crabs generally do not occur in the same habitats. Research and Monitoring Program At present, a large part of QFS s research and monitoring focus concerning the mud crab fishery is focussed on two major projects: the Long-Term Monitoring Program (LTMP); and the habitat mapping and stock abundance estimation being pursued through the NTDBIRD-FRDC-QDPI Mud Crab Project. The Long-Term Monitoring Program (LTMP) was initiated in 1999 to collect information about the status of fish stocks and key habitats and to monitor major fishery species over many years. The project has ongoing funding as it is recognised that the power is not in any individual year s data but in the long-term time-series that will develop as monitoring continues (Helmke et al. 2002). Each crab caught is identified (to the species level), measured, sexed, eggs are recorded for females (if present) and the presence of any parasites or abnormal features is also noted. As of 2002, all bycatch species are identified and recorded. Water quality is also measured annually at each site and a detailed survey of habitat characteristics is carried out every three to four years (Helmke et al. 2002). The LTMP surveys are not intended to produce an estimate of total biomass or crab density, or to fulfil the role of a formal stock assessment. Rather, the time-series of data as it develops will provide a range of independent checks on fishery-dependent measures of change in the stock from year to year. To illustrate, catch and effort statistics recorded in the LTMP will allow an estimate of annual changes in relative abundance (statewide and at a regional level). Similarly, length and sex information will allow long-term comparison of changes in population structure. Data on habitat and water quality will allow QFS to detect changes that may affect the mud crab resource (Helmke et al. 2002). The recent inclusion of bycatch recording in the LTMP enhances QFS ability to monitor the impacts of the mud crab fishery on the wider marine environment. LTMP status reports are produced biennially to analyse the data obtained and summarise the changes to the mud crab stock and habitat. The next status report is due in The results of the mud crab component of the LTMP are presented annually to CrabMAC. The NTDBIRD-FRDC-QDPI Mud Crab Project represents phase one of the threephase Five-year Research Strategy for Northern Australian Mud Crab Resources endorsed by Queensland, Northern Territory and Western Australian fisheries managers at the 1999 National Mud Crab Workshop (Calogeras 2000). The project addresses phase one of the research plan, through the following two objectives: 1. Identifying and quantifying critical mud crab habitat using remote sensing techniques; and 14

15 2. Estimating the corresponding mud crab abundance per unit of habitat using novel mark-recapture and depletion techniques (Hay and Phelan 2002). In addition to its main objectives, the project is also producing valuable initial bycatch results, and may provide some information on the impacts of the adult mud crab catch on the ecosystem generally (NTDBIRD 2002). A comparative assessment of fished and unfished areas, suggested by the Northern Territory as an extension to the project subject to available resources (NTDBIRD 2002), may provide more detailed ecosystem information. Marketing Mud crabs are sold into local and interstate markets and are a particularly important icon species to the tourist and hospitality trade. There is a small live export trade to Asia from northern Queensland centres. The dominant product form is whole crab, live or chilled. There is competition from interstate product, especially from the Northern Territory where both males and females can be sold at smaller sizes. Prices paid to fishers are consistent at about $8 12 per kilogram (Lee 2002). 15

16 PRINCIPLE 1. A fishery must be conducted in a manner that does not lead to overfishing, or for those stocks that are overfished, the fishery must be conducted such that there is a high degree of probability the stock(s) will recover. Objective 1. The fishery shall be conducted at catch levels that maintain ecologically viable stock levels at an agreed point or range, with acceptable levels of probability. Information requirements There is a reliable information collection system in place appropriate to the scale of the fishery. The level of data collection should be based upon an appropriate mix of fishery independent and dependent research and monitoring. Both fishery-dependent and fishery-independent information is collected for the Queensland mud crab fishery. This information enables stock assessment of the fishery and helps to ensure that catch and effort levels, and fishing gear and methods are all managed for sustainability. Fishery-dependent data from the commercial sector of the fishery is collected via CFISH the Commercial Fisheries Information System. Since its commencement in 1988, CFISH has collected daily data from commercial fishers about their commercial fishing activity through the use of compulsory logbooks. Two different logbooks are used in the Queensland mud crab fishery: fishers in the Gulf of Carpentaria use the Gulf Set Net Fishery logbook (see Appendix 1) and fishers along the east coast use the East Coast Net and Crab Fishery logbook (see Appendix 2). The example logbook pages reveal that identical information is collected in the Gulf and along the East Coast. All commercial fishers in Queensland have a legal obligation to provide information about their fishing activity. Section 118 of the Fisheries Act 1994 (the Act) and Section 109(1)(b) of the Fisheries Regulation 1995 (the Regulation) require that all holders of primary commercial fishing boat licences and holders of authorities to take, possess or sell fish must keep detailed statistical records about their fishing activities and provide such records to QFS. Section 118 of the Act clearly outlines that any person who fails to comply with an obligation to keep and provide the logbook or other information about fisheries required by QFS is liable to prosecution for an offence against the Act. For the mud crab fishery, the data provided to CFISH via the logbook program must include a daily record of the location fished, an estimate of the weight of mud crab caught (in kg), an estimate of other crab species caught (excepting spanner crab which is prohibited), the total number of pots used, the total number of pot lifts, and any interactions with threatened or protected species (Williams 2002). The reporting of interactions with threatened or protected species is currently being enhanced through the development of a new logbook. During 2003 all license holders will be issued with a new Species of Conservation Interest logbook (SOCI01). With this logbook 16

17 fishers will be able to differentiate the particular activity that caused the interaction for example netting, mud crab potting, etc. (Shane Gaddes, QFS, pers. comm., 2002). At present, no formal procedures exist to verify the accuracy of data provided by commercial fishers in the daily logbook returns. In light of this absence, QFS is currently in the process of designing and implementing a generic buyers returns logbook. Although still in the preliminary stage, QFS envisages that the logbook will apply to all species under quota management and other species for which QFS considers catch data verification to be a high priority (Jim Higgs, QFS, pers. comm., 2003). The CFISH logbook data is one of the primary bases for the stock assessments and analyses that QFS conducts on the mud crab fishery. More information on these assessments and analyses is provided in criteria Information on the recreational catch and effort in the mud crab fishery is sourced from RFISH the Recreational Fishing Information System. RFISH was developed in the mid-1990s following recognition that QFS required greater information on the activities of recreational fishers to ensure that fish stocks and fisheries are sustainably managed. Prior to RFISH, accurate timely estimates of even basic information such as the recreational fish catch and fishing effort was difficult to obtain. Confounding factors included the large number of anglers, their ability to fish from a wide range of environments, and the lack of legislative requirements for anglers to provide information on their fishing activities (Williams 2002). RFISH is based on a biennial two-stage survey using a statewide telephone survey and a 12-month diary program. The telephone survey is used to estimate the number of residents that fish, statewide and on a regional basis. The telephone survey is also used to identify recreational fishers willing to maintain a diary of their fishing activities for the following 12 months. Approximately 5000 fishers are usually involved in the diary program (5022 in 1997, 4506 in 1999). However, volunteer logbook programs such as the RFISH diaries typically suffer a considerable attrition rate (Bradford 1998, cited in Higgs 1999). In 1997, 3440 fishers completed the diary program (Higgs 1999) while in 1999, 3031 fishers did so (Higgs 2001). To assess the representativeness of the sample size, the total Queensland recreational fishing population (>15 years of age) was in 1997 and in The diaries allow an estimate of the catch of recreational species and species groups, including mud crabs. Again, these estimates are available statewide and on a regional basis (Higgs 2001). QFS has now conducted three RFISH surveys 1997, 1999 and The results of both the 1997 (Higgs 1999) and 1999 (Higgs 2001) surveys are fully published and the 2002 survey results will be published by late-2003 (Jim Higgs, QFS, pers. comm., 2002). QFS staff have continued to refine the RFISH survey methodology and parameters since the inception of the program in To illustrate these refinements concerning the mud crab fishery, the 1997 survey provided a single aggregated estimate for all crabs species caught whereas the 1999 and 2002 surveys provide an individual estimate of the mud crab catch. A second major refinement still being concluded concerns the conversion of catch estimates from abundance (e.g. the number of individuals) to weight (e.g. tonnage). This refinement is particularly important as it will allow the inclusion of the recreational catch estimates provided 17

18 through RFISH with the commercial catch estimates provided through CFISH in future stock assessments (Higgs 2001). With three recreational fishing surveys completed, Queensland has the most advanced ongoing assessment of statewide recreational fish catch of any state in Australia. Queensland is also heavily involved in the National Recreational and Indigenous Fishing Survey (NRIFS). The NRIFS was conducted over the 12-month period from May 2000 to April 2001 (Higgs 2001). The final project report is due mid- to late Since the NRIFS utilized a somewhat different survey methodology to that used in RFISH, comparison of the methodologies and estimates provided by each should enhance the process to estimate recreational catch and ultimately yield a more accurate assessment of recreational catch. The NRIFS will also provide a first estimate of the indigenous and international visitor catch of a number of prominent species, including mud crabs. Current advice indicates that the results of the indigenous component of the NRIFS will be available when the final NRIFS report is released mid- to late-2003 (J. Higgs, QFS, pers. comm., 2003). The Queensland Department of Primary Industries (QDPI) has an extensive fisheryindependent information base on the Queensland mud crab fishery, compiled over the past twenty-five years. This information base is a result of research conducted by QDPI, and by external researchers, and includes: Aspects of the general biology and fishery of the mud crab ( ) Methods for determining the size and sex of marketed mud crabs Queensland mud crab fishery ( ) Genetic relationship and identification of mud crabs from the Indo-Pacific region ( ) Mud crab rust spot shell disease ( ) Genetic analysis of Indo-Pacific mud crab stocks (ongoing) In addition to the above research and monitoring projects, QDPI has three research programs that focus on mud crab stocks. These programs are the primary sources of current information on the Queensland mud crab fishery: a) QFS Long-Term Monitoring Program (LTMP). b) Northern Territory Department of Business, Industry and Resource Development (NTDBIRD) and Fisheries Research and Development Corporation (FRDC) and QDPI Mud Crab Project. c) QDPI Tropical Resource Assessment Program (TRAP). a) In 1999, the Long-Term Monitoring Program (LTMP) was initiated to collect information about the status of fish stocks and key habitats and to monitor major fishery species over many years. The project has ongoing funding as it is recognised that the power is not in any individual year s data but in the long-term time-series that will develop as monitoring continues (Helmke et al. 2002). The mud crab component of the LTMP annually surveys sixteen river systems throughout the entire Queensland coastline (Map 3). Each river system is divided into four sites, which correspond to the major habitat areas within the system: foreshore, mouth, mid-estuarine and upper estuarine. This sub-division ensures that the sampling 18

19 program provides good coverage of the major areas within each river system and a reasonable coverage of crab size classes (Helmke et al. 2002). Twenty baited pots are set at each of the four sites, with each pot hauled just once. The fishing gear and methods are similar to those used by commercial operators, within certain logistic limitations. For a detailed explanation of the sampling gear and methodology see Helmke and Gribble (2002). Map 3. River system sampled in the Long-Term Monitoring Program Mud Crab 19

20 Each crab caught is identified (to the species level), measured, sexed, the presence of eggs is recorded for females and the presence of any parasites or abnormal features is also noted. Beginning with the 2002 surveys, all bycatch species are identified and recorded. Water quality is also measured annually at each site and a detailed survey of habitat characteristics is carried out every three to four years (Helmke et al. 2002). It is important to note that the LTMP surveys are not intended to produce an estimate of total biomass or crab density, or to fulfil the role of quantitative stock assessment. Rather, the time-series of data as it develops will provide a range of independent checks on changes in the stock from year to year. To illustrate, catch and effort statistics recorded in the LTMP will allow an estimate of annual changes in relative abundance (statewide and at a regional level). Similarly, length and sex information will allow long-term comparison of changes in population structure. Data on habitat and water quality will allow QFS to detect changes that may affect the mud crab resource (Helmke et al. 2002). The recent inclusion of bycatch recording in the LTMP enhances QFS ability to monitor the impacts of the mud crab fishery on the wider marine environment. LTMP status reports are produced biennially to analyse the data obtained and to summarise the changes to the mud crab stock and habitat. The next status report is due in The results of the mud crab component of the LTMP are presented annually to CrabMAC. Incorporating the results of the LTMP into the MAC process enhances CrabMAC s ability to ensure that Queensland s mud crab resources are managed sustainably, both in the short- and long-term. As the LTMP began in 1999, it is still too early to speculate on any trends apparent in the results to date. Accordingly, CrabMAC has not produced any definitive responses in the management arrangements directly related to LTMP results. As the time-series of LTMP data lengthens, QFS envisages that such a situation will develop. b) Northern Territory Department of Business, Industry and Resource Development (NTDBIRD), Fisheries Research and Development Corporation (FRDC) and QDPI currently have a collaborative research project underway on northern Australian mud crab abundance and habitat (hereafter referred to as the NTDBIRD-FRDC-QDPI Mud Crab Project). The project was initiated following the 1999 National Mud Crab Workshop (Calogeras 2000). Participants at the workshop including researchers and managers from Queensland, Northern Territory and Western Australia, and Northern Territory industry representatives, developed a Five-Year Research Strategy for Australian Mud Crabs. NSW Fisheries, though not a participant at the workshop, also endorsed the research plan. The aim is to maximise the total research productivity for the Australian mud crab resource by eliminating the replication of research in each state. The research plan consists of a coordinated threephase approach to: 1. examine the relative productivity of mud crab habitats; 2. compare stock abundance indicators; and 3. investigate the spatial differences in population reproductive characteristics (Hay and Phelan 2002). The current NTDBIRD-FRDC-QDPI Mud Crab Project addresses phase one of the research plan, through the following two objectives: 1. Identifying and quantifying critical mud crab habitat using remote sensing techniques; and 20

21 2. Estimating the corresponding mud crab abundance per unit of habitat using novel mark-recapture and depletion techniques (Hay and Phelan 2002). One component of QDPI s involvement in the project concerned the habitat-mapping element outlined in objective one. This objective was fully completed during 2002 (see de Vries et al. 2002; Hay and Phelan 2002). Regarding objective two, both NTDBIRD and QDPI Northern Fisheries Centre have completed the assessment of techniques for estimating the abundance of mud crabs in two different habitat types. A depletion-mark recapture sampling design is recommended for mangrove-lined streams while a trapping web design is recommended for foreshore mudflat areas (Hay and Phelan 2002). Completing the second objective and producing an estimate of mud crab abundance per habitat is ongoing. As at December 2002, both NTDBIRD and QDPI Northern Fisheries Centre had completed the majority of the in-field sampling with validation and analysis of the data continuing. Some preliminary results and greater detail on the project in general are available in the 2002 FRDC project progress report (Hay and Phelan 2002). The project is due to be completed in June c) In 1995, the Tropical Resource Assessment Program (TRAP Phase One) was initiated by QDPI, in conjunction with FRDC, to develop models describing stock dynamics and exploitation in North Queensland fisheries. The first phase of TRAP was concluded in 1999 with a final Technical Report released soon after (Gribble 1999). Within TRAP (Phase One), mud crab and barramundi were the two priority species upon which research was focussed. Accordingly, a number of objectives were proposed within TRAP (Phase One) specific to the mud crab resource. The final Technical Report for TRAP (Phase One) outlined that the following objectives had been achieved concerning the mud crab fishery: 1. Collated and analysed historical research and logbook statistics for mud crab from both the Gulf and East Coast inshore fishery datasets. This work was the basis of three annual reports released throughout TRAP (Phase One)(see Magro et al. 1997, 1998; Hall 1999). 2. Developed a habitat-alias model for mud crab biomass estimation, incorporating satellite imagery to determine total area of mud crab habitat and either logbook or independent surveys to establish crab density estimates in particular habitats. 3. Provided stock assessment advice to CrabMAC on the status of the mud crab fishery. 4. Facilitated QDPI partnership in the 'Five-Year Research Strategy for Australian Mud Crabs (described in (b) above). The habitat-alias model developed in TRAP is fundamentally the same model as that currently being used in the NTDBIRD-FRDC-QDPI Mud Crab Project. In fact, one of the first trials of the habitat-alias model for northern Australian mud crab resources arose as a spin-off project from the main TRAP (Phase One) project. The spin-off project Abundance estimates for Albatross Bay, Weipa was a collaborative project between QDPI and the Weipa Catchment Coordinating Group funded initially by the Queensland Fisheries Management Authority (QFMA) and subsequently through Natural Heritage Trust (NHT) grants. Two project reports have been released to date (Helmke et al. 1998; Gould et al. 2001) each of which has provided a preliminary estimate of mud crab abundance for the Weipa region. A third report, with a third preliminary estimate, is expected by mid