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EXECUTIVE SUMMARY
Fishing remains the major extractive industry in the Great Barrier
Reef (GBR) region. Diverse commercial and recreational fisheries are
widespread, and constitute multi-million dollar industries in the region.
Biological information about species targeted by fishing is necessary
but not sufficient to successfully manage the fisheries and ecosystem.
For justifiable, marketable, and effective management, biological information
must be integrated with human demographic information, understanding of
fishing practices, and estimates of the responses of fish stocks and fishing
practice to changing fishing pressure. Controlled experimental manipulations
of fishing pressure and management options have been recommended previously
as the most effective mechanisms for assessing empirically the responses
of targeted stocks, other reef organisms, and fishing practice to changes
in fishing pressure. The Cooperative Research Centre for Ecologically
Sustainable Development of the Great Barrier Reef (CRC Reef) provided
an important institutional focus for such large scale experimental research
into the effects of line fishing on the GBR, and examination of existing
and future management options to maintain current fishing standards.
Computer simulations of the population dynamics of the main target
species, Plectropomus leopardus, were used to examine the potential
for large scale (whole reef) manipulations of fishing pressure. Based
on recent field research, the simulations indicate that experimental manipulations
can be designed such that the results will have good statistical power
to detect effects of fishing and measure responses of fished stocks to
protection from further fishing. Such information is not currently available
for the GBR reef-line fisheries, but will be critical to future decisions
about management of those recreational and commercial fisheries.
We recommend an experimental design involving 4 clusters of 6 reefs
spread over 7 degrees of latitude, between Cape Flattery in the north
and the Swain Reefs in the south of the GBR.
Three treatment regimes should be applied within each cluster.
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A closed control treatment represented by 2 reefs per cluster
that have been closed to fishing historically and remain closed during
the experiment. These reefs provide our best estimates of the behaviour
of unfished, virgin stocks.
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A increased fishing treatment, represented by two reefs per
cluster that were historically open to fishing at will, and which
are fished with increased intensity for one year. These reefs are
then closed to fishing for 5 years. They provide our best estimates
of the capacity of already fished stocks to withstand more fishing,
and the dynamics of recovery of fish stocks after protection from
fishing.
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A initial fishing treatment, in which two reefs per cluster
that have been closed to fishing for 5-12 years are opened to `at
will' fishing for one year and then re-closed. This treatment will
provide our best estimates of the relationship between trends in catch
rate and changes in stock density, the size(s) of unfished stocks,
and the responses of fish stocks and fisheries to rotational harvest
strategies.
The experimental work must be complemented with sound estimates of the distribution and intensity of both recreational and commercial
line fishing over the GBR region. Provision of adequate catch and effort
information for the recreational fisheries is more difficult than for
the commercial fleet. There have been some past attempts to estimate recreational
fishing catch and effort within one year, but there are no formal longitudinal
research data available. Compilation of angling club records, the recent
implementation of a log book system for fishing charter boat operators,
increased political focus on the recreational fisheries, and the commencement
of other CRC Reef tasks to provide robust estimates of recreational reef
line and spear fishing are positive steps toward the provision of essential
information about recreational fishing on the GBR.
Information about the commercial line fishery will come from the
QFMA compulsory log-book programme, and additional sampling of the
commercial fleet as part of the experimental work and other CRC Reef Tasks.
Managed carefully, such work will greatly improve collaboration between
the research project and the fishing industry. This component of the work
will cost little, but is essential to the sensible and acceptable transfer
of results from the experiment to management of the fishery.
THIS PUBLICATION IS CITED AS:
Mapstone, B.D., Campbell, R.A. and Smith, A.D.M. (1996).
Design of experimental investigations of the effects of line and spear
fishing on the Great Barrier Reef.
CRC Reef Research Centre Ltd
Technical Report No. 7
Townsville; CRC Reef Research Centre Ltd, 86 pp.
ISBN 1 876054 05 0.
A full copy of this report may be obtained from the author(s),
and through the following libraries:
Agency libraries: Great Barrier Reef Marine Park Authority,
Townsville; Australian Institute of Marine Science, Townsville; James
Cook University, Townsville; Queensland Department of Primary Industries and Fisheries
(Brisbane and regional offices); Queensland Department of Environment
and Heritage (Brisbane and regional offices); CSIRO Division of Marine
Research, Tasmania.
Public libraries: Queensland, New South Wales, Tasmania and South
Australia State libraries; National Library, ACT.
Parliamentary libraries: Queensland, New South Wales and South
Australia parliamentary libraries.
For a hard copy (or pdf file) of the report contact CRC Reef on info@crcreef.com.
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