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National strategy for the survival of released line-caught fish: tropical reef species
Summary
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Diver inspecting redthroat emperor and coral trout at the foot of the sock 15 m from the surface
Survival rates of released line-caught tropical reef fish are being estimated by short-term field experiments and long-term tag-release-recapture methods to identify handling and release procedures that minimise post-release mortality. Two methods of assisting the released fish to overcome the buoyancy effects of swim-bladder expansion are being compared - shotline releasing and venting.
Details
| Full title | National strategy for increasing the survival of released line-caught fish: investigating survival of fish released in Australia's tropical and subtropical line fisheries |
|---|---|
| ID | FRDC 2003/019 |
| Status | Current |
| Dates |
Start date: August 2003
|
| Project leader |
Dr IW Brown, +61 07 3817 9580 |
| Aims |
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| Benefits |
Results of the research work are being extended to the recreational fishing community via the InfoFish Services Inc. National Strategy publicity program, Gently Does It. This will assist in optimising post-release survival of key tropical reef species including coral trout, redthroat emperor and red emperor, and contribute to the sustainablity of the state's extremely important reef handline fishery. |
| Methodology |
Short term: Fish are captured from a range of depths and the degree of barotauma, and their general condition and the level of hook damage is assessed and recorded. Various barotrauma-relief procedures (including shot-lining and venting) are applied, and the fish tagged and released into a floating vertical mesh sock, where they are observed by underwater video and SCUBA divers over a 3-day period. Long term: Dependent upon a tag-release-recapture program being carried out by enthusiastic recreational Queensland anglers. Target species are tagged, using the same data-recording and experimental protocols as in the short-term experiments. Differences in recapture rates will be analysed over a 2-3 year period, determining which hook design and which barotrauma-relief procedure maximise the probability of post-release survival. |
| Achievements |
To date, research has indicated that to maximise survival of released coral reef fish, anglers should consider using smaller rather than larger hooks, and circle (preferably non-offset) rather than J-hooks. If a fish that's about to be released shows any signs of barotrauma, we recommend careful venting of the swim bladder using a clean hollow needle, or recompressing using a weighted releasing shotline. Neither technique significantly increases post-release mortality. For some key reef species the data already points to a longer term benefit, either from reduced surface predation or because soft-tissue damage is minimised. |
| Research staff |
Principal investigator: Ian W Brown (Southern Fisheries Centre (SFC), DPI&F) |
| Funding |
Fisheries Research and Development Corporation |
| Collaborating agencies |
Rainforest and Reef Research Centre (RRRC), Townsville - previously the Cooperative Research Centre for Reef Research (Reef CRC) |
| Research locations |
DPI&F Southern Fisheries Centre, Deception Bay |
| Contact details |
Dr IW Brown Ph: + 61 7 3817 9580 |
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Author: Ian Brown
Page maintained by Tonia Grundy
Last reviewed 17 May 2007
