Biology, larval transport modeling and commercial logbook data analysis to support management of the NE Queensland rock lobster (Panulirus ornatus) fishery
The need for targeted research to support management of the NE QLD lobster fishery has arisen as a result of the recent and dramatic increase in catch and concern that the increase is unsustainable. In response to this concern the Queensland Fisheries Service (QFS) issued an investment warning for the fishery on 31 May 2001. Also, the NE QLD lobster population is likely part of a wider distributed stock, shared by Australian and PNG fishers in Torres Strait and now these fisheries are over-exploited and managers are taking measures to ensure sustainability. In NE QLD, there is an urgent need to gain biological and fishery information to allow implementation of management measures that will ensure catches are sustainable. The commercial catch is monitored by the QFS with a logbook program but no formal stock assessment has been undertaken using this data. However, effort and catch has doubled over the past three years, whilst CPUE has tended to decline. There is also a need to collate existing and new information on the biology of the NE QLD lobster population to assess current impacts of fishing on the stock and so that future research can be prioritised and properly designed to ensure its cost-effectiveness. Future research would likely include field studies to assist stock assessment, breeding population studies, targeted oceanographic studies and efficient observer programs. A critical need is knowledge of the extent of the breeding population and the fate of larval recruits on the NE QLD coast. There is currently pressure from the industry to open areas south of 14°S. However, for informed management decisions it is important to establish how well stocks are connected. Existing allozyme genetic data could not detect stock structure in this species. However, due to the slow mutation rates of allozymes and low variability especially in lobsters, this is not sufficient to conclude that the NE QLD fishery operates on the same genetic stock as the Torres Strait population. It is likely, given the long larval life of lobsters (6 months) that the NE QLD coast, Torres Strait and the eastern Gulf of Papua are source areas and larvae spawned there mix in the NW Coral Sea gyre and provide recruitment to these regions as well as to sink areas south of 14°S. If this is true, fishing occurs in the source area but not on the sink population; biological and genetic information is required to resolve this contrary situation.
Final report
Rock Lobster Enhancement and Aquaculture Subprogram: the nutrition of juvenile and adult lobsters to optimise survival, growth and condition
Because Australia's rock lobster fisheries are at their maximum sustainable capacity, the value of the industry can be increased only through the development of aquaculture. In the immediate term, this could be achieved by on-growing of juveniles taken from the wild and the holding of adults for weight gain or niche marketing opportunities. In the longer term, domestication of the specie/s and hatchery propagation of the juveniles will enable a sustainable rock lobster aquaculture industry to develop. In Australia, these opportunities are seriously constrained by the lack of a cost-effective and efficacious rock lobster feed. This contrasts with the developing industry in New Zealand where waste from the large mussel industry is an available and inexpensive source of feed. If feed comprises from 40 to 50% of rock lobster production costs as is the case for prawn and finfish grow-out operations, the availability of a suitable formulated pelleted feed is seen as a necessity for commercial production.
Preliminary feed’s development work (FRDC 98/303) for juvenile and adult lobsters has been initiated in an 18-month project that terminated in December 1999. Although all lobster species consumed the developed dry feed pellets, the productivity of juvenile animals was inferior to the feeding of fresh mussels. However, with adult J. edwardsii held in sea cages, the pelleted diets were equal to fresh mussel in maintaining the condition (moult frequency, weight increase and survival) and colour of the lobsters The sub-optimal performance of the pelleted diets for the juveniles is thought to have been due to the reduced attractiveness and /or sub-optimal nutrient specifications of the diet for the lobsters. This project will seek to develop improved and more cost-effective pelleted dry lobster feeds for P. ornatus and J. edwardsii juveniles and to improve the feeds management of adult J. edwardsii. Dietary improvements made with the juvenile work will be applied to adult lobsters being held under commercial sea cage conditions in Professor Geddes’ ‘On-growing Project’ (98/305). A collaborative research approach involving CSIRO, TAFI and UA and other agencies in the RLEAS will give the best prospects for achieving our aims. The likelihood of the project being successful is high because:
1. The initial Feed’s Development Project has shown dry pelleted diets to be well accepted by the lobsters and further improvements are likely upon implementation of the proposed targeted research.
2. The project will build on the already established strong collaborative linkages between related rock lobster research being carried out at CSIRO, QDPI, TAFI, UA and by industry.
3. The assembled project team has considerable expertise and an established track record in delivery of successful feed development for other crustaceans (prawns) and finfish, and have established strong collaborative linkages with the aquafeed industry to aid the rapid commercialisation of the research.
Final report
Research in FRDC RLEAS 98/303 established that tropical (Panulirus ornatus), southern (Jasus edwardsii) and western (Panulirus cygnus) rock lobsters readily consumed formulated pelleted dry feeds and exhibited a dose dependent growth response to dietary protein concentration. The derived optimum dietary crude protein dry matter specification was 49, 37 and 57% for tropical, southern and western lobsters, respectively. However, growth rates of lobsters fed diets of either fresh mussel or expensive (AUD$7,500/tonne) extruded kuruma shrimp (Penaeus japonicus) feed pellets were from one third to five-times better than for the laboratory-pelleted diets. The sub-optimal performance of the laboratory-pelleted diets was attributed to a loss of attractiveness of the food after 1–2 hours immersion in the water and/or a sub-optimal supply of nutrients critical to growth and development of the lobsters.
Based on these results, the focus of the research in this project (FRDC RLEAS 2000/212) was to enhance the lobster's acceptability of pelleted dry feeds and to advance knowledge on the animal's requirements for critical nutrients and the nutritive value of alternative protein ingredients. Additionally, research was carried out with adult southern rock lobsters to improve feeding and husbandry management practices.