3 results

Rock Lobster Enhancement and Aquaculture Subprogram: propagation techniques

Project number: 1999-315
Project Status:
Completed
Budget expenditure: $149,889.00
Principal Investigator: Piers Hart
Organisation: University of Tasmania (UTAS)
Project start/end date: 5 Sep 1999 - 12 Jun 2002
:

Need

Expansion of output from the rock lobster fishery cannot be achieved using traditional fishing methods as most wild stocks are already fully exploited. It is therefore necessary to develop an aquaculture technique that can increase the long term production of rock lobster, in a sustainable manner.

The outcomes of the FRDC workshop (project 98/300) and an earlier Perth workshop sponsored by the DISR, confirmed that culture of puerulus from eggs is biologically feasible and also appears economically viable. Production of puerulus from eggs has been achieved on a small scale in both Japan and NZ. The Japanese are far enough advanced to be considering release of cultured puerulus onto artificial reefs in the next few years. In Tasmania the phyllosoma of the southern rock lobster have been reared through 70% of the larval cycle with good survival (25%).

The priorities for further research were identified as:
· improving larval survival & growth
· improving system design/environmental requirements
· improving nutrition
· reducing the length of the larval phase.

Lower priorities were identified as:
· out of season spawning
· improving gamete quality.

However, as gametes are readily available from wild-caught broodstock, it was considered that these issues could be left for a future project.

The next stage must be to coordinate and expand the research in Australia under one project through the FRDC and CRC, in order to focus our effort on addressing the research priorities that were identified during the workshop.

This project identifies the priorities for the first year of the project and addresses a few issues that need to be determined in order to design a longer term project.

Objectives

1. Develop an artificial diet acceptable to phyllosoma of three species of rock lobster, that is water stable and easily manipulated.· Project 1. Characterise morphology and function of larval digestive system (Method 1).· Project 2. Examine biochemical changes in cultured and wild phyllosoma (Method 2).· Project 3. Develop a best guess formulated diet for use in nutritional experiments (Method 3).· Project 4. Examine the suitability of diets for phyllosoma of rock lobster (Method 4).
2. Examine mass culture systems and determine environmental requirements for phyllosoma of three species of rock lobster.· Project 5. Examine mass culture systems using southern rock lobster phyllosoma (Method 5).· Project 6. Examine environmental requirements of southern rock lobster phyllosoma (Method 6).· Project 7. Examine environmental requirements of tropical rock lobster phyllosoma (Method 7).· Project 8. Examine the effects of temperature and food density on phyllosoma of western rock lobster phyllosoma (Method 8).
3. Develop hormonal control of moulting in rock lobsters.· Project 9. Scoping study to examine the hormonal sequence controlling moulting in phyllosoma of a test species (Method 9).
4. Determine the health status of phyllosoma of southern rock lobster under culture conditions.· Project 10. Monitoring health of southern rock lobster phyllosoma (Method 10).

Rock Lobster Post Harvest Subprogram: optimising water quality in rock lobster post-harvest processes

Project number: 2000-252
Project Status:
Completed
Budget expenditure: $136,226.00
Principal Investigator: Stephen Battaglene
Organisation: University of Tasmania (UTAS)
Project start/end date: 29 Dec 2000 - 8 May 2006
:

Need

There are concerns that poor water quality may be having an affect on the health of post-capture rock lobsters. This project addresses this in three ways:

1. Determining the optimal level of ammonia in holding and transport systems. This will contribute to the understanding of optimal system design.

2. Understanding the mechanism of ammonia toxicity. This will enable industry to develop methods to counteract the harmful effects.

3. Providing information to the rock lobster industry in the appropriate form to ensure uptake of the results of research on optimising water quality, specifically in the area of oxygen and ammonia.

Objectives

1. Production of a manual on optimising the provision of oxygen during rock lobster post-harvest processes
2. Determine the median lethal concentration (LC-50) of ammonia to adult southern and western rock lobsters (stressed and unstressed).
3. Determine the physiological consequences of exposing lobsters to sub-lethal ammonia concentrations, and the consequences of further exposing lobsters to acute post-harvest stressors.
4. Production of a manual on ammonia problems during rock lobster post-harvest processes

Final report

ISBN: 1-86295-065-2
Authors: Stephen Battaglene Jennifer Cobcroft Mark Powell and Bradley Crear
Final Report • 2005-01-04 • 859.67 KB
2000-252-DLD.pdf

Summary

Rock lobsters can be exposed to poor water quality during all stages of handling and holding prior to going to market. Poor water quality reduces the time a lobster can be held alive and how many animals can be held in a system and thus may reduce profit. The quality of water can be assessed using many different measurements, with two of the most important being oxygen and ammonia (a form of nitrogen). An earlier FRDC funded study investigated oxygen and how it influenced the holding of rock lobsters. However, prior to the current study there was very limited understanding of the harmful effects of ammonia to rock lobsters. Ammonia can accumulate in holding and transport facilities via natural release of ammonia from lobsters, and from the bacterial decomposition of faeces, excess feed, and dead animals. Ammonia can be harmful to crustaceans in small amounts (or low concentrations) and even fatal if concentrations get too high. The toxicity of ammonia to aquatic animals becomes greater when other factors such as low dissolved oxygen, low salinity, and/or low pH (acidity of the water) also interact. In liquids, total ammonia comprises un-ionised ammonia (NH3), which is the more toxic component, and ionised ammonia (NH4 +; ammonium) in equilibrium. Lobsters can become stressed (having a higher demand upon their biological systems) during holding and handling but it is uncertain what effect this stress has on the ability of lobsters to tolerate ammonia. This project provided a better understanding of the effect of ammonia and other water quality measurements, on the health of stressed and unstressed lobsters.

Rock Lobster Enhancement and Aquaculture Subprogram: preliminary investigation towards ongrowing puerulus to enhance rock lobster stocks while providing animals for commercial culture

Project number: 1999-314
Project Status:
Completed
Budget expenditure: $57,064.00
Principal Investigator: Caleb Gardner
Organisation: University of Tasmania (UTAS)
Project start/end date: 29 Dec 1999 - 29 Nov 2000
:

Need

Development of a rock lobster aquaculture industry through the harvest of puerulus from the wild cannot proceed if there is a net loss of animals from the wild fishery. The concept of removing puerulus from the wild has received widespread opposition from participants in rock lobster fishing industries, and managers of the resource, as the resource is considered to be highly exploited. Rock lobster fisheries management policy in most states is specifically directed towards stock rebuilding and it is perceived that additional extraction by puerulus removal runs counter to those policies.

Current research on techniques for the extraction and on-growing of puerulus from the wild have proceeded with an assumption that puerulus extraction should be "biologically neutral". It has been proposed that "biological neutrality" can be achieved by a proportional reduction in catch of adult animals, either through a reduction in effort (eg removal of pots) or through buy-out of quota (in ITQ management). However, this mechanism for achieving biological neutrality has been criticised, as puerulus extraction is likely to occur in sheltered, heavily exploited regions - while the effort removed from the fishery may have been directed to a completely different region. In this scenario, puerulus extraction could lead to local depletion and loss of egg production, despite the concurrent reduction in effort.

The proposed project is directed to an alternative mechanism for compensating for the removal of puerulus. Reseeded animals can be released back to the same areas from which they were extracted so no localised depletion will result. Reseeding the area with animals additional to those required for biological neutrality will provide an enhancement benefit. This system has benefits to the fishing industry through enhanced yield, and also to the proposed aquaculture industry through access.

The potentially valuable on-growing industry is reliant upon the development of a mechanism for compensating for puerulus loss that does not harm the wild fishery.

Objectives

1. To develop methods to capture large numbers of 1 year old benthic juvenile rock lobsters, both for providing control animals and for monitoring survival of reseeded animals. (note that this is not puerulus collection)
2. To determine the extent of movement of reseeded and control juveniles after release, to assist in estimation of survival
3. To develop methods to assess relative survival of cultured juvenile lobsters released into a natural habitat.

Final report

Authors: Caleb Gardner David Mills Sam Ibbott Simon Wilcox and Bradley Crear