60 results
Environment

Validation of longfin eel aquaculture potential

Project number: 1999-330
Project Status:
Completed
Budget expenditure: $42,964.00
Principal Investigator: Clive Jones
Organisation: Department of Primary Industries (QLD)
Project start/end date: 11 Jul 1999 - 8 Apr 2003
:

Need

Attractiveness: World eel production is in the order of 150,000 tonnes per year, but demand is estimated at over 200,000 tonnes and increasing. Australia’s eel production has traditionally come from wild fisheries and extensive culture by way of stocking impoundments with elvers. This production has not exceeded 500 tonnes in any year, and there is little potential for any expansion from these sources. Aquacultured eel would however have immediate market potential. Recent studies (Ford and Roberts, 1996) have confirmed that longfin eels are highly regarded by both Asian and European consumers, and that attractive prices can be achieved. The proposed research will assist in increasing the supply of this valuable product.

From a benefit/cost perspective, the continuity of the longfin growout work now underway rates very highly. It will be significantly more cost-effective to continue the existing successful program rather than terminate it after 2 years, only to re-initiate it possibly 1 year later.

Feasibility: This project seeks to develop semi-intensive pond-based aquaculture of the longfin eel. This is particularly attractive as the feasibility is enhanced by advantageous characteristics of this species, relative to shortfin eels. The longfin eel has faster growth rate, is more abundant as glass eels, is adapted to the tropical / sub-tropical climate prevailing in northern Australia, and is therefore better suited to growout in outdoor ponds which are significantly less expensive to establish and operate than indoor tank facilities.

Feasibility is further enhanced by the track record of the PI who has comprehensive research experience with the aquaculture research and development of redclaw (FRDC 92/119). QDPI has excellent facilities to support the research, located in the tropics, and will subsidise the project directly with staff and operating resources.

Outcomes:
• generate biological information regarding growth rates and survival in relation to weaning, diets, grading and density
• identify health / disease problems and establish health monitoring protocols
• develop expertise in the investigators to equip them for further and more comprehensive research
• identify priority issues for further research
• evaluate the potential for developing a commercial eel aquaculture industry

Objectives

1. To assess the farmability of the longfin eel and define basic husbandry and health requirements for semi-intensive growout, with specific objectives as follows:
2. Determine suitable weaning practices
3. Develop optimal grading procedures
4. Assess the efficacy of existing commercial diets
5. Determine growth rate and survival in relation to density / biomass
6. Collect information on the parasites, pathogens and lesions of eels
7. Extend research results to industry
Industry
PROJECT NUMBER • 2008-793
PROJECT STATUS:
COMPLETED

Seafood CRC: prawn Industry black spot management: problem size and appropriate research

Summary: The wild prawn capture industry is under increasing competition from imported and domestic aquaculture product. One problem facing the industry is the frequent occurrence of black pigment on the head and tail surfaces. This condition is known as black spot and can be prevented by treating...
ORGANISATION:
Department of Primary Industries (QLD)
SPECIES
Environment
Industry
PROJECT NUMBER • 2017-019
PROJECT STATUS:
COMPLETED

Freshwater fish attracting structures (FAS): Evaluating a new tool to improve fishing quality and access to fisheries resources in Australian impoundments

This document has been compiled from various sources and, to the authors’ knowledge, represents the best advice currently available regarding the use of fish attracting structures to improve recreational angling in Australian impoundments. Although the principles outlined in this document may...
ORGANISATION:
Department of Primary Industries (QLD)
Environment
PROJECT NUMBER • 2019-062
PROJECT STATUS:
CURRENT

Knowledge to improve the assessment and management of Giant Mud Crabs (Scylla serrata) in Queensland

Researchers from the Department of Agriculture and Fisheries (DAF) Queensland, CQUniversity (CQU) and the Department of Primary Industries (DPI) NSW Fisheries are collaborating on a Fisheries Research and Development (FRDC) co-funded research project on mud crab populations in Queensland. The...
ORGANISATION:
Department of Primary Industries (QLD)
SPECIES
Industry
PROJECT NUMBER • 1999-358
PROJECT STATUS:
COMPLETED

Evaluating effective quality monitoring methods for the Australian seafood industry

A variety of rapid kit methods, both microbiological and chemical, have been evaluated with respect to their accuracy for and application to the Australian seafood industry. The information is now readily available for industry managers to base operational processing decisions on. A few kits...
ORGANISATION:
Department of Primary Industries (QLD)

Electronic cooking end point determination and the effectiveness of alternative cooking methods for Crustacea

Project number: 1998-354
Project Status:
Completed
Budget expenditure: $309,017.64
Principal Investigator: Brian Paterson
Organisation: Department of Primary Industries (QLD)
Project start/end date: 21 Jun 1998 - 24 Jun 2004
:

Need

Questions often asked that can not be answered presently by the literature include:
- When should prawns be cooked in relation to time from harvest?
- Does this have an effect on visual appearance of the cooked prawn, eg. white head etc.?
- Is there a quality and yield difference in cooking in fresh vs salt water?
- Are cooking systems which currently use boiling followed by immersion in cold water the best option. Would a lower temperature cook for a longer period improve the process?
- What is the most effective compromise between sensory acceptability and optimal recovery?

Because prawns vary substantially in size and morphology, and the cooking equipment used by industry varies in power and capacity, at present, it is impossible to determine a time based standard that will optimise yield and quality and still remain broadly applicable.

Less powerful cookers will take much longer to return to the boil than high powered units. Thus the point of returning to the boil is a somewhat arbitrary starting point as slower cookers will expose prawns to cooking temperatures for much longer periods if using a standard time.

The industry needs a simple device which will tell processors when prawns and other crustacea are cooked. This device will measure the internal temperature during the cooking of prawns and will possibly use a cumulative cooking index or formula to determine when the prawns are appropriately cooked. This device would be based on research which determines the time / temperature relationship for enzyme deactivation as the basis for cooking calculations, and would be effective regardless of the type of cooker or maximum temperature during cooking.

Objectives

1. To develop a device which will determine endpoint of cooking for crustacea by: a) developing a durable sensor for measuring the thermal centre of the crustacea. b) determining crustacean protease deactivation temperature curves.
2. To confirm that the endpoint for cooking is determined by protease deactivation by: a) confirmation trials of several species, sizes and cooking rates. b) determining the effects on possible melanosis development, sensory and textural quality and yields against a chosen reference such as farmed prawns.
3. Evaluate alternate cooking, processing and handling conditions for prawns.
4. Build 10 prototypes of the device for industry to trial.
5. Extend results to industry through workshops, publications and the media.
6. OPTIONAL: To further develop the cooking endpoint device for two other crustacean species with methods subject to the out-comes of the first two objectives.
7. Extend the results to industry through workshops, publications and the media.

Final report

ISBN: 0 7345 0269 9
Author: Steven Slattery & Brian Paterson
Final Report • 2004-03-19 • 585.99 KB
1998-354-DLD.pdf

Summary

A prawn cooking meter and self-centring thermocouple clip has been successfully developed for monitoring the cooking of prawns. This cooking meter provides a much needed control tool for ensuring reliable and consistent quality required of modern quality assurance programs.

The design of the prawn cooking meter relies upon the fact that enzymes that discolour and soften the flesh of cooked prawns are a major cause of quality loss. Ideally, cooking should destroy these enzymes, but experience shows there is typically not enough control over the cooking step on vessels and in processing factories to bring this about. Simple methods of timing cooking do not take account of the complex factors that can influence the rate of product heating such as size and quantity of prawns, cooker efficiency etc.  This results in variable quality product, which can exhibit mushiness and discoloration including black-spot (melanosis) and autolysis. 

This problem has been solved by developing a meter (Objective 1) that actually monitors the heat put into a prawn in the cooker and signals the end-point of cooking when the product is cooked enough to destroy the target enzymes, without the over-cooking that might otherwise cause toughness and weight loss. The progress of the cook is tracked by fitting a prawn typical of the batch into a robust clip, also developed in this project.  The clip places a temperature sensor in the thermal centre of the tail of the prawn. The cooking end-point used by the meter is calculated from the thermal destruction rates of the enzymes that are achieved at particular temperatures. These were determined in in vitro experiments using extracts from several prawn species.

The use of the meter was tested in a number of confirmatory trials (Objective 2) where the prototype of the meter was used to successfully cook prawns of several species and size, and was, as long as the cooker approached boiling temperatures, independent of the performance of various kinds of prawn cookers used.  

The meter was used to monitor a number of alternative cooking techniques (Objective 3). Of these, most interest was in sub-boiling or simmering of prawns. However, after cooking trials, this practice cannot be recommended. It fails to reach the threshold temperatures necessary to denature the enzymes that cause softening, discoloration and black spot. The underlying algorithm in the meter requires the prawns to warm significantly above the temperatures reached by simmering. Perhaps a higher sub-boil temperature can be used, as the final temperature, even in boiling prawns, is typically in the order of 90-95oC. Industry interest in steam tunnels was considered in passing by the project team, but trials were not undertaken.  There appears to be no reason why this technology would not be suitable.

After the meter validation trials, ten prototype meters were manufactured and tested by industry with favourable results (Objective 4).  These tests used a number of species under commercial conditions with cooperation of processors of both farmed and wild prawns in Queensland and Western Australia. Important feedback was obtained on the design features needed in a commercial model of the meter.  

Dissemination of the results to companies participating in the trials was rapid. In addition, two workshops were held for prawn farmers in south and north Queensland (Objective 5). A workshop manual and training video have been prepared.  The successful development of the prawn cooking meter has also been widely promoted in trade magazines and general media. Negotiations are in progress with a company wishing to manufacture and market the meters. 

The cooking meter was tested on four other types of crustaceans (Objective 6) namely yabbies, redclaw, western rock lobsters and sand crabs.  Suitable algorithms have been developed for all four species.  Its use proved relatively straightforward for freshwater crayfish, which are of similar size and morphology to prawns, and the same self-centering clip could be used. However, further work is required to develop a practical temperature sensor clip for use with rock lobsters and crabs.

Keywords: processing, cooking. prawn, shrimp, lobster, crustaceans, crayfish, redclaw, temperature; enzyme de-activation, spoilage, meter, monitor.

Population dynamics and management of spanner crabs in southern Queensland

Project number: 1995-022
Project Status:
Completed
Budget expenditure: $262,552.00
Principal Investigator: Ian Brown
Organisation: Department of Primary Industries (QLD)
Project start/end date: 18 Dec 1995 - 30 Jun 2000
:

Objectives

1. To estimate the size of the south Queensland spanner crab stock.
2. Determine the appropriateness of existing spawning closure arrangements.
3. To determine whether catch size-distribution can be used to estimate population age-structure and growth rates.
4. To evaluate the impact of post-discard mortality amongst sub-legal crabs on yields, and promote the development (by industry) of less damaging apparatus.

Final report

Authors: Ian Brown John Kirkwood Shane Gaddes Cathy Dichmont & Jenny Ovenden
Final Report • 1999-09-01 • 13.01 MB
1995-022-DLD.pdf

Summary

Spanner crabs (Ranina ranina) represent a valuable resource to southern Queensland and northern NSW. The fishery became established in the late 1970s, and as a result of an almost exponential increase in fishing effort between 1992 and 1995 an output-controlled limited entry management arrangement was introduced. During that period catches increased from about 800 to over 3,000 t, as the fishery expanded northwards to previously unexploited grounds, and a profitable live-export market was developed in south-east Asia.
The Queensland fleet comprises some 240 vessels specifically licenced to take spanner crabs in Managed Area A, which is subject to a Total Allowable Commercial Catch (TACC), currently set at 2600 t. Another 310 vessels are licenced to fish only in Managed Area B (north of the main fishing grounds) where the TACC does not apply. At present the TACC is competitive, but in the near future an Individual Transferrable Quota (ITQ) system is to be introduced.
Trends in commercial fisheries catch-effort statistics indicate that the spanner crab stock in southern Queensland is currently being harvested at a sustainable level. However several questions remain with respect to the application of the commercial logbook data, possibly the most important of which is how well commercial catch-per-unit-effoti represents stock abundance. The spatial distribution of spanner crabs is patchy, and the fishery operates such that patches are located, targeted and fished down. This can potentially lead to a situation of hyperstability, where the stock is actually declining despite catch rates remaining constant. This highlights the expected value of the fishery-independent monitoring programme currently being planned by QDPI with (in the case of the spanner crab fishery) a significant level of cost-recovery from industry.
Previous attempts to estimate growth rate of spanner crabs resulted in little consensus, due in part to inadequate sample sizes (length-based methods) and uncertainty surrounding the effects of tagging on growth (tag-recapture methods). Our initial objective was to determine whether the length-based methods would work if the samples were very large.
 
Variability in the size-structure of even very large samples of adult crabs was so great that we could place little confidence in growth estimates obtained from this type of data. Because of this, we negotiated a change in research direction with FRDC, focussing on two alternative approaches to the question of growth rates. The first was to investigate growth in pre-recruits. The second was to quantify the likely effect of tagging on moulting and growth, and to determine the extent of growth rate differences between NSW and Queensland.
Very small spanner crabs are not taken by baited tangle nets, regardless of mesh size, so a different sampling arrangement was required. A two-track channel dredge was successful in capturing intact megalopae and early juvenile stages, which provided length frequency data of considerable value to estimating pre-recruit growth. However because of its small size only very limited samples were able to be collected. To increase the sampling volume we developed a substantially larger, hydraulically­assisted dredge. This device has been field-tested on several occasions, but it has not yet been developed and used to full effect.
Laboratory experiments demonstrated that tagging had an adverse effect on weight increase and survival of spanner crabs, suggesting that growth rate estimates based on mark-recapture techniques may be biased. Of the several different types tested, anchor tags were superior in terms of ease of application and visibility. Recognising that the results may be biased, we released 4,804 tagged crabs at sites throughout the fishing grounds, to determine whether growth of spanner crabs in Queensland waters is significantly different from that in NSW, reported in a previous study. Fourteen of the 221 crabs recaptured in 1998 had moulted, with growth male growth increments being greater than those offemales (X = 11.86 and 7.40 mm respectively). Recapture rates were significantly higher for males than females, and were also significantly greater for larger individuals of each sex. This suggests that tag mortality was greater in the smaller size-classes. Recaptured crabs had moved distances ranging from O to 45 km since release, but showed no tendency to move in any particular direction.
Our length-based assessment model has not yet been successful in producing useful estimates of the relevant stock performance indicators for use by management. This was due to the lack of contrast in the CPUE data, the relatively short data time-series, the extreme spatial and temporal variability in population size-structure and sex-ratio as represented in commercial catches and research samples, and the absence of definitive growth data.
Mitochondrial DNA analysis indicated that the east-coast spanner crab fishery comprises a single unit stock, and there thus appears to be no biological justification for separate management arrangements in different geographic areas.
 
Analysis of reproductive chronology indicates that the timing of the existing spawning closure is appropriate for minimising mortality amongst egg-bearing female spanner crabs across the entire fishery, and we recommend that the closure be retained in legislation.
 
Exploratory surveys for spanner crabs conducted in two areas outside the current fishing grounds did not reveal any significant quantity of crabs, although small numbers were captured at two sites amongst the Swain Reefs. From the available information it seems unlikely that there are any major unexploited populations of spanner crabs remaining in Queensland waters.
We have demonstrated that limb damage to undersized discarded spanner crabs has a major effect on their survival under natural conditions. Poor handling practices in the fishery result in considerable mortality amongst discarded small crabs, highlighting the need for continuing fisher education and ongoing investigation of alternative catching apparatus.
 
The two major issues for further research into the spanner crab fishery are (i) deriving a robust estimate of the species' growth rate, (ii) investigating the source of the extreme variability in size­frequency and sex-ratios in population samples.
Industry
PROJECT NUMBER • 2009-774
PROJECT STATUS:
COMPLETED

Seafood CRC: harvest strategy evaluations and co-management for the Moreton Bay trawl fishery

The Moreton Bay otter trawl fishery is a multispecies fishery, with the majority of the catch composed of various species of prawns, squid and Moreton Bay Bugs. The project was an initiative of the MBSIA and developed from concerns over a number of issues. These included concern over declining...
ORGANISATION:
Department of Primary Industries (QLD)
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