Industry

Potential for rock lobster aquaculture in Australia

The Australian rock lobster fishery is an important marine resource making up 25% of Australia’s total fishery landings and presently worth around $450 million per annum. However, while many are currently well managed, most Australian rock lobster fisheries are at their maximum sustainable capacity. Small increases in the value of production may be made in the future by increasing sales of live lobsters and/or targeting periods of high demand, but total gains are likely to be minimal. The real potential for significant growth appears to be through some form of aquaculture.

There is growing interest around the world in aquaculture of rock lobsters and this has recently extended to Australia. A number of States are investigating rock lobster aquaculture potential in various forms, the dominant methods including:

1. On-growing of adults through a moult to increase weight whilst allowing sale at periods of peak demand/ value,
2. On-growing of wild-caught puerulus (newly-settled juveniles) to a small (and potentially very valuable) market size of around 200-300 g, and
3. Culture of phyllosoma from eggs through the 11 larval stages to puerulus and subsequent ongrowing to market size as above.

In addition, the potential exists through improved survival rates, for aquaculture to provide stock for reseeding and enhancement of the wild fishery.

In all cases there are many issues that require further research. Some specific aspects relevant to the various aquaculture and enhancement opportunities include:

Ongrowing of adults

Investigations into the ongrowing of adult southern rock lobsters (Jasus edwardsii) have been ongoing since 1994, mainly in South Australia. The lobsters are held in cages at sea and are presently being fed with natural diets (trash fish/mussels). There is the potential to achieve weight gains of around 20% by growing the animals through the annual moult, representing a 60% return on investment. Some difficulties have been encountered with the renewal of leases for sea cages in South Australia, and hence interest in this form of aquaculture is changing focus to land-based raceway systems.

Ongrowing of wild-caught juveniles

In Tasmania (southern rock lobster, J. edwardsii), Western Australia (Western rock lobster, Panulirus cygnus) and Queensland (tropical spiny lobster, Panulirus ornatus) there is a growing interest in the potential for capturing wild puerulus and ongrowing them to a small market size. The basis for this is that there is thought to be high mortality of wild puerulus in their first year post settlement (anywhere from 75-97%) . However, recent results are showing that, if these animals are brought ashore and ongrown in tanks, the mortality is minimal (2% in Tasmania). Therefore the theory is that aquaculturists can ongrow the ‘excess’ that would have died in the wild. The animals are caught in collectors deployed at sea and quite large numbers have been caught in Tasmania.

A major issue associated with the on-growing of wild caught juveniles is how to compensate the wild fishery for their removal. This has been addressed in Tasmania after considerable discussion, by an agreement that 25% of all captured puerulus will be returned to the wild after one year of growth in captivity. This will ensure that there is no negative impact on the wild fishery and in fact, will probably lead to enhancement of the fishery. The success of this method obviously depends on the survival rate of released juveniles.

Culture of puerulus from eggs

Spiny rock lobsters have a complicated life cycle. The eggs hatch as tiny spider-like transparent larvae or phyllosoma. The phyllosoma drift in ocean currents for up to two years until they are ready to settle on a substrate and metamorphose into puerulus. The phyllosoma phase involves 11 distinct morphological stages and up to 17 moults (J. edwardsii). Culture of phyllosoma to puerulus has been successfully achieved in Japan and New Zealand in very small numbers. The phyllosoma can be fed on Artemia or chopped mussel flesh, but nutrition seems to be the major problem. The time to settlement can be greatly reduced in culture compared to that of wild larvae. In the long term, the culture of lobsters from eggs may prove to be the answer to the future sustainability of rock lobster aquaculture.

Rock lobster aquaculture and enhancement developments in Australia

Although there are a number of commercial groups on-growing adult rock lobsters, there is presently no commercial aquaculture of puerulus or larvae in Australia. Despite this, there is considerable interest across Australia in the establishment of rock lobster aquaculture enterprises. With this in mind, and given the recent developments in rock lobster aquaculture in other countries, the Fisheries Research and Development Corporation established the Rock Lobster Enhancement and Aquaculture Subprogram (RLEAS) in July, 1998. The purpose of this Subprogram is to provide technology for use in Australian rock lobster enhancement and aquaculture systems so they can be internationally competitive while operating in harmony with the wild fisheries.

A total of fourteen projects have now been funded under the auspices of the RLEAS. In the initial phases of the subprogram, research projects investigated a wide variety of topics including puerulus collection, "biological neutrality" and juvenile release, nutrition, health, system design and husbandry, and larval rearing. The subprogram has now consolidated with an increased focus on larval rearing (particularly the nutrition of phyllosoma), nutrition of juveniles to one year of age, the survival of aquaculture reared juveniles returned to the wild, factors influencing the incidence of tail fan damage in captive lobsters, and the hormonal manipulation of larval phases to reduce the length of the life cycle.

The RLEAS research program now represents an international collaboration between scientists in Australia and researchers at the National Institute of Water and Atmospheric (NIWA) Research in New Zealand. Rock lobster aquaculture in New Zealand has been underway for some years with a number of commercial enterprises in existence. Research conducted at NIWA has assisted the establishment of these enterprises and as a result, these scientists have a wealth of knowledge to contribute to the subprogram. In addition, involvement of New Zealand in the RLEAS has allowed the research to be extended to the "pack-horse" lobster (J. verreauxi) in addition to the more common commercial species in Australia.

Puerulus collection

Research in Western Australia and Tasmania has examined the development of collection methods for puerulus from the wild. Large ‘fluffy’ collectors set at different depths and in different areas off the Western Australian coast have been trialed with varying levels of success. This research has recently been extended to Tasmania where a number of different collector types on long lines are being examined. The Western Australian research has been hampered by low puerulus settlement, but has found that inshore collectors are more successful than those situated at a distance off shore. In Tasmania a survey of commercial aquaculture facilities has revealed some interesting spatial patterns of settlement on submerged structures while the research component has led to the development of suitable cost-effective collector types.

Biological neutrality

Historical data on the settlement of puerulus in specific areas in Western Australia has been used to assess the potential impact of puerulus removal on subsequent wild populations of adult lobsters. Extensive statistical analysis has been employed to assess a range of scenarios. Due to the sensitivity of the data and the potential implications of the results for both aquaculture and the wild capture fishery, the RLEAS Steering Committee is currently devising a strategy for release and dissemination of the information.

Nutrition

Nutrition research is being conducted on tropical, western and southern rock lobsters. All stages from early juveniles through to adults are being examined and cost effective manufactured diets are being evaluated. Recent work has shown that the protein content of diets for southern rock lobsters should be approximately 450 g/kg with lipid levels around 100 g/kg. The most noteworthy outcomes of nutrition experiments in all states to date are the apparent superiority of mussels over other diets and the distinct colour differences observed in lobsters fed different diets. It has been demonstrated that inclusion of approximately 100 mg/kg of carotenoids in southern rock lobster diets produces lobsters which are close to the natural colour of wild caught juveniles.

On-growing of juveniles

On-growing of juvenile rock lobsters takes place in tanks and the animals grow best on a diet of fresh mussels. Artificial diets are readily accepted, but the growth and survival rates are not as good as with mussels. Despite this, artificial diets do support exceptional growth of southern rock lobsters if supplemented with mussels three times per week. Hides are placed in the tanks to reduce cannibalism that can occur at the moult. Under these conditions a marketable size can be reached in 2 years (Tasmania) or a weight of 500 g in 1 year (Queensland) with very low mortality levels.

System requirements

System design research is defining environmental requirements of juvenile and adult tropical and southern rock lobsters as well as identifying system design criteria for on-growing of adults. A recent experiment in Tasmania has shown that a temperature of 18-22° C is optimal for growth and survival of southern rock lobsters. Further research is required to identify optimal growing conditions in South Australia. Both dry and moist manufactured feeds have been examined as cheap alternatives to fresh mussels, yet cannibalism at the moult and a disease causing blackening and necrosis of the tail sections requires further attention.

Larval rearing

Research on propagation of the southern rock lobster in Tasmania has resulted in the successful culture through 10 of it’s 11 larval stages in around 9 months. The outcomes of an International Workshop organised by the Tasmanian Aquaculture and Fisheries Institute through the Rock Lobster Enhancement and Aquaculture Subprogram suggest that the problems involved in larval rearing make it a risky proposition. However, economic and biologically feasibility on a commercial scale do appear to be achievable. Subsequent research on the rearing of rock lobster phyllosoma suggests that the nutrition of these larval stages is limiting and new techniques need to be developed for the delivery and improved utilisation of feeds. It is hypothesised that nutritional status of the phyllosoma towards the end of their larval phases has a significant influence on settlement.

Enhancement of the wild fishery

As an adjunct to the above research in rock lobster aquaculture and enhancment, research underway in Tasmania is concentrating on the survival of wild caught on-grown juveniles after release back into the wild. Using electronic tagging methods released juveniles have been tracked for up to two weeks with no mortalities recorded.

Rock lobster enhancement and aquaculture is now a reality in Australia and has existed in New Zealand for some years. The following outlines some of the current activities by region:

Developments in rock lobster aquaculture by State

Tasmania

Collection of puerulus from the wild and on-growing to a marketable size is now underway in Tasmania. This form of aquaculture and enhancement is based on high mortality of wild puerulus in their first year post settlement (anywhere from 75-97%) compared with animals brought ashore and ongrown in tanks where the mortality is minimal (2% in Tasmania). This gives rise to the theory aquaculturists can ongrow the ‘excess’ that would have died in the wild. This year in Tasmania, 7 licences were issued for the collection of 50,000 puerulus each. The licences are for an initial 12 month period, after which time they will be reviewed (in terms of successful application and commitment to use) by the Tasmanian Department of Primary Industries. The licences were issued at a cost of $5,000 each and a condition of use is that approximately 25% of the total number of puerulus collected are re-seeded into the wild fishery as juveniles at 1 year. An officer will be appointed within the DPI to monitor both the collection and reseeding processes. The development of conditions associated with the issuing of licences was in full consultation with the existing wild capture sector. At present, collection of puerulus has commenced, with collection from salmon nets alone (all of which would have otherwise died during normal net cleaning processes) already yielding 2000 puerulus which have been provided to the Tasmanian Aquaculture and Fisheries Institute for re-seeding research.

There are a number of interesting points to note in relation to issuing of puerulus collection licences in Tasmania:

• There were at least 20 applicants for the 7 licenses on offer signalling significant interest in rock lobster aquaculture;
• Of the 7 licenses issued, none are currently held by commercial rock lobster fisherpeople.

South Australia

Aquaculture activities in South Australia continue to focus on on-growing and value adding to adult wild-caught lobsters. In the past, pontoons have been used to hold and feed lobsters prior to sale facilitating more control over the market the lobsters are sold into and the timing of the sale. There is the potential to achieve weight gains of around 20% by growing the animals through the annual moult, representing a 60% return on investment. Some difficulties have been encountered with the renewal of leases for sea cages in South Australia, and hence interest in this form of aquaculture is changing focus to land-based raceway systems. Current activities include investigations into the holding and feeding of lobsters in land-based tanks using both existing flow through systems and infrastructure or recirculation systems.

Queensland

M G Kailis have forged an alliance with the Queensland Department of Primary Industries to investigate the potential of culturing and growing tropical rock lobsters. To date, research has focused on many aspects of production, but propagation of tropical lobsters remains the highest priority. Phyllosoma have been grown to Stage 9 over a period of 85 days, with each attempt improving survival rates.

New Zealand

Rock lobster aquaculture based on quota buy-out schemes in return for puerulus collection licenses (in the order of 1 tonne of quota in return for 40,000 puerulus) has been in place in New Zealand for some years. The success of these ventures has been variable.

Other developments

Interest continues to grow in other Australian states. Opportunities to develop rock lobster aquaculture enterprises in conjunction with existing aquaculture infrastructure is being investigated in both the Northern Territory and Western Australia. For example, management of pearl lines involves regular inspection and it is clear that puerulus are regularly brought to the surface with the lines. The frequency of appearance, the dominant species present and the potential to harvest and on-grow these puerulus requires further investigation, but is an existing consideration.

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