2 results

Rock Lobster Enhancement and Aquaculture Subprogram: reducing rock lobster larval rearing time through hormonal manipulation

Project number: 2000-263
Project Status:
Completed
Budget expenditure: $180,838.00
Principal Investigator: Michael Hall
Organisation: Australian Institute Of Marine Science (AIMS)
Project start/end date: 9 Oct 2000 - 15 Mar 2006
Contact:
FRDC

Need

As with the majority of world wild fisheries, the sustainable landings of Australian rock lobsters have reached their maximum. Nevertheless, demand from the world markets to which Australia exports to continue to increase. Increases in rock lobster production will only arise from aquaculture production.

One approach towards aquaculture production is that of ranching. It is already possible to grow rock lobsters from newly-settled puerulus harvested from natural recruitment, in commercial fisheries areas, to market size in 2-3 years using cost effective diets. However, natural settlement is unreliable and recruitment from the wild fishing sector has many political implications. The only method for resolving this problem is to develop a cost/effective larval culture technique to produce pueruli from eggs.

The participants at the FRDC Rock Lobster Propagation workshop in 1999 concluded that culture of pueruli from eggs was biologically feasible and worthy of investigation. The workshop identified several components needing to be addressed by further research in order to improve the survival and growth of larvae through the extended larval phase, including:

1. Advancing the design of larval culture systems.
2. Identifying larval nutrition requirements and production of cost effective larval feeds.
3. Reducing the long larval period.

Preliminary research of the RLEAS subprogram in 1999/00 indicates that progress can be made towards addressing the three major constraining components. Based on the recent Workshop for Rock Lobster Enhancement and Aquaculture Subprogram (RLEAS) in Hobart (February 2000), the RLEAS Steering Committee requested that separate funding applications be submitted for the research effort towards issues of nutrition and larval period.

Objectives

1. To identify triggers for moulting to evaluate a shortening of the larval phase.

Final report

The development of manufactured attractants as a means to harvest prawns specifically

Project number: 2000-256
Project Status:
Completed
Budget expenditure: $304,920.00
Principal Investigator: Michael Hall
Organisation: Australian Institute Of Marine Science (AIMS)
Project start/end date: 17 Dec 2000 - 17 Feb 2006
Contact:
FRDC

Need

This proposal represents an attempt to develop alternative technologies that would allow the prawn trawl industry to meet present and future strict environmental standards at a reduced operating cost. The proposal is not without risk, but reflects a genuine need to consider alternative fishing approaches outside the current thought envelope. If successful it would allow the industry to claim high environmental standards, meeting or exceeding the community expectations.

Alternatives to established fishery harvest methods are essential to meet ecologically sustainable development (ESD) requirements as dictated by international (UN) and national legislation (both federal and state) covering the marine environment. In recent years drift nets have been banned in many areas due to their detrimental impacts on non-targeted species and ecosystem structure. Similarly, ground trawling has been identified as a harvest technology that requires either restriction or banning due to its putative detrimental impacts on benthic ecosystems and disruption to food webs. Whereas drift net has been largely replaced by the sustainable and targeted method of hook and line harvesting, there are few alternatives to ground trawling.

Traps are used extensively for the harvesting of crustacea. Suitably designed pot traps can result in a minimum of by-catch and target individuals of specific size classes. However, pot trap fisheries utilise food as bait by which to attract the targeted species into the trap. Baited traps and pots are used for the commercial harvesting of pandalid prawns in the east Pacific and North Atlantic, where average catch/vessel/day of fishing effort is 80-110 kg. A smaller pot fishery exists for penaeid prawns in various parts of the Pacific basin and the Caribbean. However, attempts to date to develop a large pot trap fishery based on food bait for penaeid prawns have been largely unsuccessful.

It is proposed that chemical attractants, and not food bait, be examined as a means to harvest penaeid prawns in pots. The development of alternative harvest methods could form a non-trawl fishery with minimum by-catch, open up new areas to harvesting which are unsuitable for trawling, and produce a less stressful method to collect broodstock P. monodon prawns for the aquaculture sector as well as have spin-off potential for the development of pot trap fisheries for other species of crustacea.

Objectives

1. 1. To quantify the attraction and specificity of pheromones from crustacea in experimental environments.
2. 2. To develop methods suitable for isolating and concentrating pheromones from crustacea, especially penaeid prawns.
3. 3. To identify a mechanism for manufacturing a bait incorporating these novel attractants.

Final report

ISBN: 0-642-32261-9
Author: Michael Hall