Condition: Fisheries
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| Annual catch
statistics for selected species in the East Coast Trawl Fishery. For Tiger
Prawns annual CPUE varies widely with slight downwards trends. For scallops
the decrease in CPUE is more pronounced.
The use of CPUE data for stock assessment is problematic. It is possible that decreases in stock abundance are occurring that are not reflected in CPUE data. |
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| Note: Scallop fishery data for 2000 not yet available. |
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| When all species catches are combined, the total harvest does not show any clear trends. However the CPUE has shown an apparent decline |
Note: Some of the material contained in this chapter is out of date and currently under review (1/7/2004)
Condition: Fisheries
From the fisheries perspective, detailed and quantitative assessments of the condition of target species and ecological sustainability of fisheries are only just becoming a reality. However, data from 1988 onwards are available and suggest that most target species in the Queensland East Coast Trawl Fishery (ECTF) are being exploited at a high level with some species fully exploited. For most species, the average annual harvest and daily catch rate per vessel (or Catch Per Unit Effort – CPUE) vary significantly from year to year with few clear trends. However, when considering total catch of all target species, there has been an apparent decline in the CPUE per boat between 1988 and 2000. Some target species such as scallops show more dramatic declines while others show declining catch rates only in specific trawl grounds.
The use of modern technology and navigation aids (for example Global Positioning Systems) makes trawling increasingly efficient. This is likely to disguise trends in CPUE statistics that would otherwise indicate a decline in stocks. Additionally, the tendency of some species to aggregate allows ‘targetting’ of these species which further reduces the accuracy of CPUE data. Seasonal and inter-annual variability in stock abundance complicate the use of CPUE as an indicator of stock condition. Furthermore, data collected prior to the introduction of logbooks suggest that historically, stocks may have yielded much higher catch rates which would indicate that the fishery had already declined by 1988. Considering the uncertainties of the available catch per unit effort data and the trends for some target species, there is concern that declines in stock condition have occurred and there is a need for more information to both clarify the extent of any declines and to assess the sustainability of the fishery.
With the commencement of the Environmental Protection and Biodiversity Conservation Act 1999 (EPBC Act) in July 2000, the Queensland trawl fishery is being assessed against the Commonwealth’s ‘Guidelines for the Ecologically Sustainable Management of Fisheries’. The Guidelines require the collection of detailed information on the sustainability of the fishery to evaluate it against principles of ecologically sustainable development. Although there is little such information currently available, the Queensland Fisheries Service has initiated several projects to collect this information including the development of critical stock assessment models and sustainability indicators.