Research > Collaborative linkages program > State linkage projects > project description Research: Collaborative linkages State linkage project: Assessing the Benefits of Closed Fishing Areas for Spawning Aggregations and Egg Production for Coral Trout Introduction Coral trout is a valuable finfish species that inhabits coral reef systems in Australia. Like most other finfish species, coral trout is managed mainly through catch and size limits, however, closed fishing areas also provide a measure of protection from exploitation. Worldwide, closed fishing areas have been shown to provide larger and more fish within their boundaries (Roberts et al. 2001, Nardi et al. 2004) review by (Halpern 2003). However, there is limited empirical data to show that they provide benefits to fish stocks. This project aims to examine whether closed fishing areas provide a benefit to coral trout at the Abrolhos Islands, Western Australia. Current research on the coral trout P. leopardus has focused on the populations in the Great Barrier Reef (Ferreira and Russ 1992, Russ et al. 1996, Light and Jones 1997, Samoilys 1997, Zeller 1997, Adams et al. 2000). At the Houtman Abrolhos Islands, Western Australia, Nardi et al. (2004) demonstrated an increased size and abundance inside no-take zones (Reef Observation Areas) compared to adjacent fished areas. These results have formed the basis for this current study, that is, to examine the potential ow on effects to the fishery as a part of the biomass build up inside the reserve. In application for an Australian Postgraduate Industry Award (APAI) was submitted in December 2003 to provide a PhD scholarship for the study. Aims/objectives • To determine the age and growth of fished populations of P. leopardus at the Abrolhos Islands • To compare the age structure of P. leopardus populations inside and outside Reef Observation Areas (ROAs) • To describe several spawning aggregations of P. leopardus populations inside and outside ROAs • To assess the reproductive output of spawning aggregations of P. leopardus inside and outside ROAs. Discussion The project was approved by ARC in mid 2004. A suitable PhD candidate was sought through advertising between September and October 2004. The scholarship advertisement and selection criteria were distributed through various universities and government agencies which resulted in 7 respondents. A candidate was selected (Jason How) and commenced on the 1st of February 2005. The initial phase of the project has required the preparation of a proposal, including details of experimental design, timeline and budget accompanied with relevant literature review and synthesis. This is currently being undertaken by the student. As the project requires a biological assessment of Coral Trout in order to address the objectives, the student, in conjunction with the supervisory panel (G. Hyndes and J. StJohn), has established links with members of the fishing community to procure the necessary samples. However, to date there appears to be a small commercial catch from which to sample. This has been exacerbated by the tendency to sell Coral Trout whole, thereby limiting the ability of the project to gain samples. Foreseeing this as a potential problem later in the project, the collection of another species has begun. The Red-throated or Sweetlip Emperor Lethrinus miniatus is another species which is found on the mid-west coast of Western Australian and to date has not had the biology studied. This species also appears to benefit from fishery protection areas (D. Watson, unpublished data) making it a suitable species to replace Coral Trout should this latter species continue to produce low sample numbers. Summary and Conclusions At this preliminary stage, there are no conclusions that can be drawn as there is little data available. The PhD project is at the proposal stage, which will define its structure over the following 3 years. Currently the viability of Plectropomus leopardus as the focal study species is being assessed. References Adams, S., B. Mapstone, G. R. Russ, and C. R. Davies. 2000. Geographic variation in the sex ratio, sex specific size, and age structure of Plectropomus leopardus (Serranidae) between reefs open and closed to fishing on the Great Barrier Reef. Canadian Journal of Fisheries and Aquatic Sciences 57:1448-1458. Ferreira, B. P., and G. R. Russ. 1992. Age, growth and mortality of the inshore coral trout Plectropomus maculatus (Pisces: Serranidae) from the central Great Barrier Reef, Australia. Australian Journal of Marine and Freshwater Research 43:1301-1312. Halpern, B. S. 2003. The impact of marine reserves: do reserves work and does reserve size matter? Ecological Applications 13:S117-S137. Light, P. R., and G. P. Jones. 1997. Habitat preference in newly settled coral trout (Plectropomus leopardus, Serranidae). Coral Reefs 16:117-126. Nardi, K., G. P. Jones, M. J. Moran, and Y. W. Cheng. 2004. Contrasting effects of marine protected areas on the abundance of two exploited reef fishes at the sub-tropical Houtman Abrolhos Islands, Western Australia. Environmental Conservation 31:160-168. Roberts, C. M., J. A. Bohnsack, F. R. Gell, J. P. Hawkins, and R. Goodridge. 2001. Effects of marine reserves on adjacent fisheries. Science 294:1920-1923. Russ, G. R., D. C. Lou, and B. P. Ferreira. 1996. Temporal tracking of a strong cohort in the population of a coral reef fish, the coral trout, Plectropomus leopardus (Serranidae: Epinephelinae), in the central Great Barrier Reef. Canadian Journal of Fisheries and Aquatic Sciences 53:2745-2751. Samoilys, M. A. 1997. Movement in a large predatory fish: coral trout, Plectropomus leopardus (Pisces: Serranidae), on Heron Reef, Australia. Coral Reefs 16:151-158. Watson, D. 2005. Unpublished data on abundances of finfish at the Houtman Abrolhos Islands with depth, island groups, and protection from fishing. Zeller, D. C. 1997. Home range and activity patterns of the coral trout Plectropomus leopardus (Serranidae). Marine Ecology Progress Series 154:65-77. Investigators G. Hyndes – Edith Cowan University, PI K. Nardi – Department of Fisheries, Co-PI J. StJohn – Department of Fisheries, PI [collaborative linkages program]

 

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