Adapting to Change: Minimising Uncertainty about the Effects of Rapidly-Changing Environmental Conditions on the Queensland Coral Reef Fin Fish Fishery
Tobin, A., Schlaff, A., Tobin, R., Penny, A., Ayling, T., Ayling, A, Krause, B., Welch, D., Sutton, S., Sawynok, B., Marshall, N., Marshall, P., and Maynard, J. (2010) Adapting to Change: Minimising Uncertainty about the Effects of Rapidly-Changing Environmental Conditions on the Queensland Coral Reef Fin Fish Fishery. Report. Fishing and Fisheries Research Centre, James Cook University, Townsville, Qld, Australia.
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With the severity and intensity of tropical cyclones predicted to increase with global climate change (Webster et al. 2005), the need to understand the effects of these events on fisheries production is paramount. The northern tropical margin of the Australian continent is subject to tropical cyclone influence each monsoon season. Although the increased rainfall that accompanies these events may have positive benefits for some fisheries production (e.g. Halliday et al. 2008; Staunton-Smith et al. 2004), the influence of the many other biophysical changes that accompany tropical cyclones (eg: habitat alteration and water temperature fluctuations) is less certain. One fishery for which anecdote reports negative influences of tropical cyclone impact is the Queensland Coral Reef Fin Fish Fishery (CRFFF). Prior to the impacts of severe TC Hamish in March 2009, popular anecdote reported that the influence of TC Justin (March 1997) on catch rate of the primary target species of the commercial sector, common coral trout (Plectropomus leopardus), were particularly negative and long lasting (up to twelve months). Somewhat surprising, the depressed catch rate of trout was accompanied by a noticeable increase in catch rates of red throat emperor (the secondary target species of the CRFFF) that was acknowledged though not quantified by Leigh et al. (2006).
The influence of tropical cyclones on the performance of the CRFFF is an annual event, though mostly restricted to loss of potential fishing days due to the inclement and unpredictable weather that accompanies the monsoon season. The 'average' cyclone that impacts the Great Barrier Reef World Heritage Area (GBRWHA), within which the CRFFF operates, is generally short lived and crosses the reef structure rapidly in an east to west direction. With the last two decades, most tropical cyclones impacting the GBRWHA have been low intensity systems (category 1 or 2). The influence of these types of systems on reef structure (coral coverage and diversity) and associated small-bodied reef fish communities has been well documented (e.g. Wilson et al. 2009; Emslie et al. 2008). However, as the monitoring used for these reports focuses initially on corals and secondarily small-bodied fish communities, the ability to measure changes in large-bodied reef fish communities is either not attempted, or compromised. As such, no robust assessment has been completed to understand the changes in abundance and availability of CRFFF primary target species in response to cyclone impacts.
TC Hamish impacted the southern section of the GBRWHA in March 2009, and quickly galvanised fishers, managers (both fisheries and Marine Park) and research scientists with a common need to understand the initial impacts, as well as possible lagging influences of this truly unique event. TC Hamish was the most severe storm system to impact the GBRWHA in recent decades, rated a category 5 system when first crossing emergent reef structure east of Bowen before a slight dissipation into a category 4 system that tracked southeast neatly bisecting the southern emergent reef structure that supports the majority of fishing effort and catch of the CRFFF. Commercial fishers were the first to witness and verbally document the wide spread structural damage caused by TC Hamish. The destruction, scouring and displacement of reef habitat were significant and widespread covering 3° of latitude (19° to 21° inclusive). In addition to the structural reef damage, commercial fishers were also quick to report depressed catch rates of all species throughout the directly impact areas.
The need for this project was clear, a recent unique cyclone event with significant impacts on fisheries productivity and reef structural integrity; an historic cyclone event whose impacts have been acknowledged (Leigh et al. 2006) though not quantified; claims of associated socio-economic hardship; and difficulty for resource managers to appropriately assess and address the situation due to a lack of robust data and assessment methods. As a result the objectives of the project were formulated during two crisis workshops, during which helpful cash contributions from the Great Barrier Reef Marine Park Authority (GBRMPA) ($18,000) and James Cook University (JCU) Fishing & Fisheries Research Centre (FFRC) ($22,500) were offered.
Objective 1, to use a fishery-independent survey technique (UVC) to assess and quantify reef structural damage as well as any changed reef species abundances and community structures, was completed three months following TC Hamish impact. Structural reef damage, unsurprisingly, was documented to be as high as 66%. Surprisingly, in contrast to the anecdotal reporting from commercial fishers of poor overall (but particularly coral trout) catch rates, the UVC methods revealed nominal increases in coral trout abundances and no measurable change in fish community structure on TC Hamish impacted reefs.
The outputs of Objectives 2 and 3 however presented a quandary by quantitatively documenting greater than 30% reductions in catch rates of coral trout and red throat emperor throughout all fishery grids in southern GBRWHA waters impacted by Hamish (spanning 3° of latitude). This pattern of depressed catch rates lagged for at least nine months (until December 2009 and possibly beyond), effectively confusing any attempts to relate these changed catch rates to abiotic factors including structural damage and SST. The fish were still on the reef (Objective 1), but were not interacting with the fishery. Some uncertain factor(s) were responsible for changing the ecological behaviours of targeted reef fishes, particularly coral trout.
Objective 5 identified historical event TC Justin (March 1997), as having even more pronounced effects on catch rates within the CRFFF than TC Hamish (March 2009). TC Justin was a unique system being long-lived (24 days), though low severity. Structural reef damage was not adequately measured, but was likely minimal relative to TC Hamish. This system was however responsible for a defined and unique cool water anomaly that is considered the likely driver of depressed catch rates of coral trout (greater than 50%) and increased catch rates (up to 200%) of red throat emperor. Some uncertainty exists though, as the spatio-temporal effects of the cool water anomaly and the changed coral trout and red throat emperor catch rates were not aligned.
Effort shift was the only adaptive tactic demonstrated by full-time CRFFF commercial fishers. Larger vessels moved more than smaller vessels, though decisions in moving needed to consider lower beach prices in unaffected northern waters as well as the secondary affect of effort congregation. An option existed for fishers to diversify their fishing by targeting other species, however few vessels are appropriately equipped and market price differentials between export live coral trout and domestic fresh fish are too wide to provide sufficient economic returns.
The socio-economic surveys of commercial fishers conducted for objective 4 highlighted two relatively consistent themes. Mitigation of the negative impacts on the CRFFF caused by severe tropical cyclones would be best achieved either by government assistance (similar to terrestrial based drought or disaster relief funding) or reviewing the zoning arrangements of the GBRWHA with a view to accessing some reefs currently closed to fishing. The likelihood of either suggestion being enacted is highly uncertain. Some fishers and working group suggestions included removing unnecessary and impeding management controls, as well as the availability of low interest loans. Working groups formed during the life of the project continue to deliberate over suitable options.
The project outputs clearly demonstrate catch rates within the CRFFF can be significantly and adversely affected by some cyclone events. Understanding the biophysical drivers of these changed catch rates is difficult due to the variable and unique nature of each cyclone event. However, it is clear from project outputs that the negative effects of a cyclone may significantly alter catch rates and that these effects may linger for at least twelve months post-event. The gradual dominance and reliance for economic viability of the commercial sector on live coral trout, has stifled pre-existing adaptive capacity. The infrastructure investments and fishing behaviours of fishers targeting live coral trout are not amenable to changing market places; an ability that may well offer some adaptive capacity to the commercial sector of the CRFFF. In contrast, recreational and charter fishing sectors with their diversified fishing and targeting practices are immune to cyclone influence.
A suggested pro forma for an action plan to track, adaptation plan and possibly mitigate the negative influences of future unique cyclone events is a draft proposal at this time, and will need to be strengthened based on the outcomes from two working groups formed during the last six months. Considerations for further research should include: (1) Identifying the most appropriate data recording system for the CRFFF that will allow timely interrogation of catch data that is not available currently; (2) Canvassing options for building adaptive capacity into a fishery that is currently highly vulnerable to change due to economic reliance on a single species destined for a single market place; and (3) Better understanding the possible drivers of the sustained changes in ecological behaviours of reef fish following cyclone passage.
|Item Type:||Report (Report)|
Fishing & Fisheries Research Centre Technical Report No. 11
|Keywords:||cyclone, Great Barrier Reef, adaptation, fisheries, Coral Reef Fin Fish Fishery, tropical cyclones, coral trout, red throat emperor, depressed catch rates, effort displacement, causal factors, vulnerability, adaptability, socio-economic, indicators, fisheries management|
|FoR Codes:||05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050209 Natural Resource Management @ 100%|
|SEO Codes:||83 ANIMAL PRODUCTION AND ANIMAL PRIMARY PRODUCTS > 8302 Fisheries - Wild Caught > 830204 Wild Caught Fin Fish (excl. Tuna) @ 100%|
|Deposited On:||18 May 2011 12:02|
|Last Modified:||08 Aug 2011 15:59|
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