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PROJECT NUMBER • 2000-142.20
PROJECT STATUS:
COMPLETED

Towards a national strategy for mud crab research - mud crab workshop

A workshop was held in Darwin, the Northern Territory (NT) in May 1999, to develop a National Strategy for Research on Mud Crab ( Scylla sp.) in Australia. Fisheries managers and researchers from Western Australia, the NT and Queensland attended, along with Industry representatives from the NT. The...
ORGANISATION:
Department of Industry Tourism and Trade
Environment
PROJECT NUMBER • 2000-142
PROJECT STATUS:
COMPLETED

Methods for monitoring abundance and habitat for northern Australian mud crab Scylla serrata

A significant achievement of this project has been the completion of mapping of coastal wetland habitats using remote sensing techniques, which provided a complete broad-scale coverage of mud crab habitats in the NT and Qld. A major outcome/output of this work has been the incorporation of the...
ORGANISATION:
Department of Industry Tourism and Trade
SPECIES
Environment
PROJECT NUMBER • 2000-139
PROJECT STATUS:
COMPLETED

Quantification of changes in recreational catch and effort on inner Shark Bay snapper species following implementation of responsive management measures

A 12-month creel survey of recreational boat-based fishing in Shark Bay, Western Australia was conducted between May 2001 and April 2002 to estimate the catch of pink snapper. During the survey 431 boat crews were interviewed at public boat ramps of which 414 had been fishing. The information...
ORGANISATION:
Department of Primary Industries and Regional Development (DPIRD) WA
Industry
PROJECT NUMBER • 2000-138
PROJECT STATUS:
COMPLETED

Minimising the cost of future stock monitoring, and assessment of the potential for increased yields from the oceanic snapper, Pagrus auratus, stock off Shark Bay

The investment in this project has resulted in a substantially more extensive set of age composition data than would have otherwise been possible. This in turn has underpinned stock assessment modeling that has provided the basis for determining that the commercial fishery for snapper in Shark...
ORGANISATION:
Department of Primary Industries and Regional Development (DPIRD) WA
SPECIES
Environment
PROJECT NUMBER • 2000-137
PROJECT STATUS:
COMPLETED

Determination of the biological parameters required for managing the fisheries of four tuskfish species and western yellowfin bream

Data have been collected on the biology of western yellowfin bream and four tuskfish species that are of the type and quality required by managers for developing appropriate plans for conserving the stocks of these five commercial and recreational species. Emphasis was thus placed on determining (1)...
ORGANISATION:
Murdoch University
Environment
PROJECT NUMBER • 2000-135
PROJECT STATUS:
COMPLETED

Regrowth of pilchard (Sardinops sagax) stocks off southern WA following the mass mortality event of 1998/1999

This project produced time series of estimates of spawning biomass for pilchards in four purse seine management zones in Western Australia, three on the south coast and one on the west coast. The pilchard stocks in Western Australia have recovered strongly since the 1998/99 mass mortality. This...
ORGANISATION:
Department of Primary Industries and Regional Development (DPIRD) WA
SPECIES

Biology and stock assessment of the thickskin (sandbar) shark, Carcharhinus plumbeus, in WA and further refinement of the dusky shark, Carcharhinus obscurus, stock assessment

Project number: 2000-134
Project Status:
Completed
Budget expenditure: $528,470.00
Principal Investigator: Rod Lenanton
Organisation: Department of Primary Industries and Regional Development (DPIRD) WA
Project start/end date: 29 Dec 2000 - 16 Nov 2006
Contact:
FRDC

Need

Presently, no stock assessment for thickskin sharks has been completed in Western Australia. New management arrangements are being proposed for the West Coast Demersal Gillnet and Demersal Longline Fishery, Western Australia’s two Northern shark fisheries and the Commonwealth Tuna and Billfish Fisheries (which could lead to a dramatic increase in longline fishing effort in Western Australia). It is necessary for fisheries managers to have a much better understanding of the catch of thickskin sharks, the status of their stocks and the catch of other long lived carcharhinids, such as the dusky shark, as a basis for future management decisions.

There is also a need for a methodology to be established on which to base future stock assessments for thickskin sharks. The stock assessment process requires a better understanding of the species’ biology in Western Australia than is currently available. With the northern and western fisheries for thickskin sharks separated by a large closed area, studies of stock discrimination and movement are necessary to determine the appropriate geographic scale for management of this species.

Bycatch of (particularly adult) thickskin and dusky sharks by ‘non-shark’ fisheries needs to be quantified and considered in relation to Australia’s international conservation responsibilities. If the exploitation of these species is shown to be unsustainable the future viability of valuable fisheries (eg. Southern and Western Tuna and Billfish) may be threatened, unless this bycatch can be eliminated or minimised.

Objectives

1. Study the biology of thickskin sharks in Western Australian waters, including: (i) Movement patterns(ii) Age and growth(iii) Reproductive biology(iv) Diet(v) Stock Discrimination
2. Determine the level of mortality and exploitation of thickskin, dusky and related oceanic shark species in Western Australian waters by all fishing methods
3. Conduct stock assessments, including risk assessment of management options for thickskin sharks and refine the assessment of the status of the dusky shark stock

Final report

ISBN: 1-877098-75-2
Author: Rod Lenanton
Final Report • 2006-02-05 • 5.67 MB
2000-134-DLD.pdf

Summary

The purpose of this project was to collect the biological and fishery information necessary to conduct a stock assessment of the sandbar (known locally as ‘thickskin’) shark, Carcharhinus plumbeus and to improve and update the existing stock assessment for the dusky shark, Carcharhinus obscurus.  Results from this project have already been used by the Western Australian Department of Fisheries to determine appropriate management arrangements for the State’s shark fisheries to ensure the sustainable exploitation of these species.  Results have also assisted the WA target-shark fisheries in conducting Ecologically Sustainable Development (ESD) assessment in order to meet Department of Environment and Heritage ecological assessment requirements for maintaining the fisheries’ export approval.

During the mid to late 1990s, changes in targeting practices of vessels operating in the west coast zone of the temperate WA target-shark fisheries caused rapidly escalating sandbar shark catches.  By 1998, sandbar sharks had overtaken dusky sharks as the primary component of the west coast fishery’s catch and had become the 3rd largest component of the temperate fisheries’ total catch.  At the same time, a demersal longline fishery, targeting sandbar shark off the Pilbara and Kimberley coasts began to develop and sandbar catches also began to increase dramatically in the State’s north.  Given this species’ demonstrated vulnerability to overfishing, a formal assessment of the status of this stock and sustainable levels of exploitation became imperative.

The current project therefore collected the biological and fishery-related data that was necessary for accurate stock assessment and developed assessment models appropriate for this long-lived species.  Extensive sampling was undertaken in the target fisheries, as well as in those fisheries that were identified as having a significant bycatch of sharks.  Additional research was conducted through a series of cruises on board the WA Department of Fisheries research vessels Flinders and Naturaliste.  Commercial sampling involved the collection of operational data from the various fisheries, e.g. fishing locations, dates, set times, depths, gear characteristics, etc., as well as identifying and measuring catches, collection of biological data and samples and tagging large numbers of sharks.  Fishery independent sampling allowed data to be collected from areas in which commercial vessels are prohibited from operating, in areas where commercial fishers choose not to operate and with fishing gear-types in areas where commercial vessels are not permitted to use them.

Previous FRDC funded research into WA’s shark stocks (projects 93/067 and 96/130) focussed on the traditional target species of the State’s temperate target-shark fisheries, i.e. dusky shark, C. obscurus, gummy shark, Mustelus antarcticus, and whiskery shark, Furgaleus macki.  One of the key findings of this previous research was that, whilst the exploitation of dusky sharks in the target fisheries was likely to be sustainable, their sustainability was dependent on a very low level of mortality of older sharks outside the temperate shark fisheries.  Since this research was undertaken, several potential and developing sources of adult dusky shark mortality were identified.  Consequently, the assumption that there was a negligible level of exploitation of older dusky sharks could no longer be relied upon and further advice on the status of this species was required. In addition, it was necessary to update the biological parameters and exploitation rates used in the previous assessment with new data, derived from project 96/130 and the current study.

Characterisation of the inshore fish assemblages of the Pilbara and Kimberley coasts

Project number: 2000-132
Project Status:
Completed
Budget expenditure: $472,686.74
Principal Investigator: Stephen J. Newman
Organisation: Department of Primary Industries and Regional Development (DPIRD) WA
Project start/end date: 5 Sep 2000 - 18 Mar 2005
Contact:
FRDC

Need

Inshore demersal fish stocks in Australia’s north-west face increased exploitation pressure by an ever increasing number of recreational fishers in direct competition with an adjacent commercial fishing industry. There is, therefore, an urgent need to determine the species distribution and the composition of demersal scalefish resources in the inshore region of north-western Australia in waters outward from the shoreline to depths of 30 metres, including the documentation of the abundance and diversity of any significant finfish by-catch of prawn trawlers operating within the region, as a basis for formulating rational management plans for the exploitation of the demersal scalefish resource among user-groups.

The sharing of the inshore demersal fish resource in this region will require careful future management to ensure sustainability and avoid conflict among these user groups. This project will provide baseline information on the species composition and relative abundance of the inshore fishes of Australia’s north-west and identify possible nursery areas of species of commercial and recreational fishing significance which may need protection, possibly as nursery closures, in the future. Furthermore, in order to facilitate sagacious management plans and to safeguard the interests of commercial and recreational fishers, the baseline information on the nearshore fishery resources of the north-west provided by this study can be used to assess the impact of any possible access restrictions that may be imposed in areas nominated as future marine reserve sites in north-western Australia.

Objectives

1. To determine the overall catch of the key species of commercial and recreational fishing significance (that is, the recreational catch, commercial catch and other landed catch).
2. To determine the species composition and relative abundance of the inshore demersal finfish resource from the shoreline outward to a depth of 30 metres along the inner-continental shelf in north-western Australia.
3. To determine the nursery areas of fish species of commercial and recreational significance in the Pilbara and Kimberley regions.

Final report

ISBN: 1-877098-40-X
Author: Stephen Newman
Final Report • 2004-07-02 • 9.95 MB
2000-132-DLD.pdf

Summary

The catches of the main fish species obtained by commercial, recreational and charter boat fishers along the Pilbara and Kimberley coasts have been determined by analysing the Department of Fisheries Western Australian Catch and Effort Database System (CAES), the results of a recreational creel survey and the statutory monthly reports of catch and effort by charter boat operators.

The weight of finfish caught by nearshore and inshore commercial fishers along this coast during 2002 was approximately 590 tonnes. The total annual recreational fishing effort along the coast between Onslow and Broome in 2002 was estimated as 190,000 fisher days, which yielded approximately 320 tonnes of fish. The 111 licensed charter boat operators in the Pilbara and Kimberley undertook 3628 tours in 2002, during which they caught 53 tonnes of fish. Thus, the total catch from all three sources approached 1000 tonnes.

Nearshore, shallow waters on beaches and in mangroves and intertidal pools in three regions along the Pilbara and Kimberley coasts were sampled during the wet and dry periods of two consecutive years. Data derived from the resultant catches were used to determine the ways in which fish species use the different habitat types and how the characteristics of the fish faunas varied with latitude, habitat type and season. 

The fish catches from all habitat types collectively yielded 170 species representing 66 families. Fifty three of these species are fished commercially and recreationally along the Pilbara and Kimberley coasts, and a further 17 fish species are caught solely by recreational fishers. The most abundant species included the blue and king threadfin salmons, salmon-tailed catfish, the blue-spot and large-scale mullets, queenfish, western school whiting, Quoy’s garfish, Moses snapper and estuary rockcod. 

Some species, such as the two threadfin salmons, spend the whole of their life cycle in nearshore, shallow waters, whereas others, such as Moses snapper and estuary rockcod, use those waters solely as a nursery area. Species such as the two threadfin salmons and also whiting species were caught predominantly over bare sand, whereas species such as the large-scale mullet and the nervous shark were obtained mainly from mangroves, and Moses snapper and estuary rockcod were collected almost exclusively from intertidal pools.

The species compositions of the fish assemblages were influenced not only by habitat type, but also by season and region and also apparently the extent of tidal action and thus turbidity. Differences between the compositions in the extreme wet and dry periods found in the region were attributable to emigrations and immigrations of large numbers of particular species at certain times. For example, mature catfish aggregate in nearshore, shallow waters during the wet period. 

This project has synthesised the available data from commercial, recreational and charter boat fisheries with baseline survey data throughout the region.  In order to build on the outcomes of this project a number of priority areas for research in this nearshore zone have been identified.

These priority areas of research include; estimation of biological parameters of key species for the purposes of fisheries management (a list of key species is provided in the Further Development Section of this Report); evaluation and assessment of recreational and aboriginal netting activities in the Pilbara and Kimberley region of north-western Australia; determination of the genetic stock structure of the key species of commercial and recreational fishing significance in the nearshore areas throughout north-western Australia to define the appropriate spatial scale for fisheries management; and refinement of commercial and recreational data collection programs in the Pilbara and Kimberley region of north-western Australia.

Keywords: Tropical, commercial, recreational, nursery habitats, nearshore reefs, estuaries, beaches, intertidal, rockpools.

Assessing short-term movements of western rock lobsters by analysis of carbon and oxygen isotope ratios in their exoskeleton

Project number: 2000-131
Project Status:
Completed
Budget expenditure: $33,456.00
Principal Investigator: Lionel Glendenning
Organisation: Department of Primary Industries and Regional Development (DPIRD) WA
Project start/end date: 5 Sep 2000 - 26 May 2003
Contact:
FRDC

Need

Reporting of visible anchor tags by commercial fishers is believed to be biased in some circumstances. There is therefore a need to develop a fishery independent technique of identifying the origin of migrating whites lobsters so as to address the extent of movements of these animals between management zones, without having to rely on visible tags.

Objectives

1. To investigate the factors affecting the carbon/oxygen isotope composition of the exoskeleton of western rock lobsters as a location specific chemical signatures for that species.
2. To apply these results as a method for determining the locality and depth (temperature) of a lobsters origin, at the time of its most recent moult.

Final report

ISBN: 0-7309-8461-3
Author: Lionel Glendenning

Predicting and assessing recruitment variation - a critical factor for the management of the mother-of-pearl (Pinctada maxima) fishery in WA

Project number: 2000-127
Project Status:
Completed
Budget expenditure: $346,257.50
Principal Investigator: Anthony Hart
Organisation: Department of Primary Industries and Regional Development (DPIRD) WA
Project start/end date: 29 Dec 2000 - 29 Sep 2006
Contact:
FRDC

Need

Historically, total allowable catches (TAC) of respective zones in the pearl oyster fishery have been changed in response to significant fluctuations in the previous year’s catch rate (catch per unit effort). These changes, however, have been influenced by factors other than variations in stock abundance, e.g. as changes in available technology or variations in fishing efficiency due to weather conditions or water clarity.

In order to make more reliable projections on future catch and effort there is a need to move away from reliance on retrospective catch data. In order to do this, information supplied to decision makers should include: 1) the size structure (length frequency) of past catches; 2) information on the abundance of pre-recruits (piggyback spat); 3) information on important environmental variables affecting stocks; and 4) other factors affecting catch rate such as water clarity and the use of new technology (e.g. GPS).

A recommendation from Project No. 95/41 states:
"The relationship between "piggyback" spat settlement, environmental effects and recruitment to the fishery which can be used to forecast increases/decreases in abundance should be developed. This enables changes to quota to be forecast to allow forward planning in pearl seeding and farm operations."

A framework for the collection of this data is needed, as pearl oyster fisheries have large fluctuations in recruitment over time, and management needs to base quota decisions on the presence or absence of emerging year classes. Collection of this data will give a more stable signal on the "health" of the fishery and allow more confident predictive assessments to be made.

Objectives

1. To establish set protocols for piggyback spat sampling within the pearl oyster fishery and develop a database for the storage of data collected.
2. To establish set protocols for length frequency sampling within the pearl oyster fishery and develop a database for the storage of data collected.
3. To establish a database of factors affecting catch rate.
4. To examine links between spat sampling data set, environmental factors and the abundance estimates for the pearl oyster fishery.
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