3 results

In situ time-stamping of abalone shells to determine how abalone stocks can be aged.

Project number: 1995-004
Project Status:
Completed
Budget expenditure: $249,980.00
Principal Investigator: Robert W. Day
Organisation: University of Melbourne
Project start/end date: 12 Jul 1995 - 14 Sep 2002
Contact:
FRDC

Objectives

1. This project will determine the timing and regularity of the calcite layers deposited under the spire of abalone shells, through extensive field based tagging and "timestamp" marking of abalone.
2. We propose to achieve objective 1 for populations of blacklip abalone at three sites in Victoria, three sites in Tasmania and one site in New South Wales
and also for populations of greenlip abalone at two sites in South Australia.
3. We aim to determine how to interpret the layers in abalone shells, how reliable such interpretations are, and how layer formation may vary between localities.
4. We will use this information to determine the age distribution of abalone at a number of sites.
5. We aim to be able to predict where and how layers can be used to age abalone in stocks in Southern Australia.

Final report

ISBN: 0-7325-1616-1
Author: Rob Day
Final Report • 2002-01-25 • 933.56 KB
1995-004-DLD.pdf

Summary

If abalone can be accurately aged, this would be a fundamental tool for more effective management of abalone fisheries.  Several authors have proposed ageing abalone by grinding or cutting abalone shells, and counting the shell layers deposited beneath the spire.  Other authors have cast doubt on this method.  What is uncertain is how reliable these age estimates are.  To construct useful models to assess and manage abalone stocks, it is important to know the accuracy of the data on which the model is based.  Furthermore, it is labour intensive to collect age data, and if these data are very inaccurate, then resources are wasted in collecting it.

This project aimed to find out how reliable and accurate the ageing method was, by investigating the timing and the periodicity of layer formation in abalone shells. It seemed possible that the ageing method might work reasonably in some areas, but not in others.  Thus we planned to repeat the work at many places in the hope that we could predict where ageing would be useful for managing the blacklip and greenlip abalone fisheries of Victoria, Tasmania, New South Wales and South Australia.

Project products

Scientific publication • 683.36 KB
1995-004-PDT-1.pdf

Summary

Ionoluminescence (IL) combined with particle induced X-ray emission (PIXE) imaging has been employed to identify intrinsic growth bands in the spire region, and extrinsic bands at the growth edge of Australian Black-lip abalone shell (Haliotis rubra). Previous studies using optical flood cathodoluminescence, scanning electron microscope cathodoluminescence (SEM-CL) and Raman spectroscopy on samples from the same population suggest that the visible luminescence is due to Mn2+ activated calcium carbonate. In this study we confirm Mn2+ as the activator in both the spire and growth edge regions of the shell.

Scientific publication • 2001-01-05 • 2.13 MB
1995-004-PDT-2.pdf

Summary

Boring predators and epibionts often damage the shells of molluscs. In abalone, spionid polychaete worms bore holes into the shell and live within the shell matrix (Shepherd and Huchette, 1997). Shepherd and Huchette (1997) found that these worms can infest entire populations, severely weakening the shells of some individuals which can lead to mortality. Given the potential consequences of boring attacks, do abalone show any response these attacks?

Investigation of methods to age abalone

Project number: 1992-040
Project Status:
Completed
Budget expenditure: $180,733.75
Principal Investigator: Robert W. Day
Organisation: University of Melbourne
Project start/end date: 25 Oct 1992 - 29 Jun 1998
Contact:
FRDC

Objectives

1. To learn how to age abalone in order to reuce the costs and increase the efficiency of management in Tasmania, NSW, Victoria, South Australia and possibly Western Australia.

Final report

ISBN: 07325-15300
Author: Dr R.W. Day
Final Report • 1997-08-05 • 2.59 MB
1992-040-DLD.pdf

Summary

Management of the valuable Australian abalone fishery is difficult because catch/effort information for abalone does not provide warnings of declining stocks. In fact abalone fisheries in Alaska, California and Mexico have collapsed or declined dramatically, with little warning. Management must rely on a detailed knowledge of how fast abalone grow, when they become adult, how many eggs they produce, and how fast they die of natural causes. But these statistics vary between areas, and it would be very costly to measure them at enough sites for efficient management. Management of fin­fish stocks has been revolutionised by accurate methods to age fish, using layers in the ear bones. Ageing abalone was identified as a high priority as long ago as 1986 in an abalone research review for the then FIRDC. An ageing method would allow biologists to work out growth, natural death rates etc. rapidly and at low cost. The industry would benefit from increased security, as uncertainty about the state of the stocks is a major problem for stakeholders. A reliable method would be used by state organisations to assess stocks more effectively, thus reducing the risk of a collapse or severe fluctuations in quota.

Previous work showed layers in the spire of the shell might be useful to age both blacklip and greenlip abalone, but the evidence relates only to juveniles , and in some areas layers did not correspond to age. We proposed to show when and how age could be estimated from layers, by "timestamping " tagged abalone at sites in each state. "Timestamping" involves staining the shell layer that they deposit over a few days. When the abalone were recovered, the number of layers deposited after the timestamp stain would show how regularly layers are deposited. We set out to mark abalone shells with fluorochrome stains , used by dentists to look at the growth of teeth, and to timestamp rings in fish ear bones. Work in New Zealand had also shown that abalone could be marked with a fluorochrome.

The project began in December 1992. By June 1993 we had established that abalone were stressed and often died after injecting stains, but they were unaffected when immersion in seawater dosed with the stains, and we had tested and compared five stains in the laboratory, and identified concentrations and immersion times that produced strong marks. This achieved our first milestone. Milestone 2 was the demonstration of the "timestamping" method in the field. By the end of 1993 we had developed underwater staining tanks, and collected, tagged and stained abalone with two fluorochrome stains underwater. Our results were reported at abalone divers meetings , and the international abalone conference in Hobart in February 1994. The symposium paper is now published.

Environment
PROJECT NUMBER • 1999-215
PROJECT STATUS:
COMPLETED

Links between seagrass habitats, piscivorous fishes and their fish prey

This project has increased our understanding of the importance of seagrass habitats to larger, commercially valuable, species of fish by combining experimental and correlative scientific principles. We found that many small fish use seagrass habitats for nutrition and to avoid predation by large...
ORGANISATION:
University of Melbourne
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