The impacts of the rezoning of the Great Barrier Reef Marine Park on southern deep water reef-associated fish populations
Project Leader: Dr Peter Doherty, AIMS & Assoc Prof Garry Russ, JCU
In the first-ever examination of the fauna associated with large, discrete deep water reef bases in the southern Great Barrier Reef (Pompeys, Swains and Capricorn-Bunker groups), MTSR-funded researchers surveyed 16 reef pairs (one zoned green and one blue) using baited remote underwater video stations (BRUVS) up to ~60 m depth. A diverse fauna (~360 species) comprised of fish, sharks, rays and sea snakes was revealed, demonstrating the importance of these deeper water habitats for biodiversity conservation and fisheries sustainability in the region. The primary outcomes of the survey were:
- Zoning had a minor but detectable effect on the maximum number of fish (maxN) observed, but this was detectable only in habitats dominated by corals.
- The maxN for unfished and bycatch species was generally similar around blue (fished) and green (no-take) reefs within reef groups.
- Coral trout, red emperor and red-throat emperor - species particularly prized in both recreational and commercial fisheries - were 1.05, 0.28 and 5.74 individuals (per BRUVS set) more abundant on coral-dominated reefs in green (no-take) zones, than in blue (fished) zones.
- Grey reef sharks (which are taken as bycatch) were more abundant in coral-dominated, open sand and rubble habitats on green (no-take) reefs compared with blue (fished) reefs, particularly in the Swains and Pompeys.
- Target and bycatch species generally had lowest maxN around the Capricorn-Bunker reefs, and white-tip reef sharks were not recorded there in green (no-take) zones.
The consistency of the response of most species targeted by fisheries strongly suggests a positive effect of zoning, although the magnitude of the response - particularly for coral trout - is less than that recorded in shallower habitats of these reefs. Data on spatial and temporal variation in fishing effort in the deep habitats around reef bases were not available, and for this reason these results should not be extrapolated regionally or throughout the Great Barrier Reef Marine Park. It is plausible that fishing around the deep reef bases in these remote southern reefs occurs at such a low level that zoning has negligible effects on local fish abundance in areas already under little to no fishing pressure.
Lost fishing line in green (no-take) zones indicates breakdown in compliance
Project Leader: Dr Peter Doherty, AIMS & Assoc Prof Garry Russ, JCU
Recreational fishers regularly get “snagged” when fishing in coral reef habitats, losing fishing tackle when it becomes entangled on the reef. While most non-stainless steel fishing hooks corrode rapidly, monofilament nylon fishing line can remain in place on the reef for many years. Researchers took advantage of this unfortunate occurrence, using the amount of entangled fishing line sighted during underwater fi sh surveys as a proxy for relative fishing effort. No significant differences were detected in the amount of discarded fishing line sighted in green (no-take) and blue (fished) zones within any island group in 2009. This lack of difference between zones was most pronounced in the Palm Islands, northeast of Townsville, where the amount of fishing line present in green (notake) zones was just ~20% less than that observed in the blue (fished) zone. This is particularly concerning given that the vast majority of the fishing line observed in the Palm Islands in December 2009 had accumulated in just two years (volunteer divers from Reef Check Australia removed all lines from two of the three sites within green zones, and one of the three fi shed zone sites during December 2007), and closely mirrors a documented decline in green-zone coral trout abundance at this location over the same time period. Sites located on the western side of Orpheus Island (in relatively close proximity to the Orpheus Island Research Station and the Orpheus Island Resort) were those in which the lowest amounts of fishing line were located and removed. It is suggested that ‘passive surveillance’ from both the research station and the resort is having a significant effect on the locations in which fishers are choosing to illegally fish. These results suggest that rates of non-compliance with zoning regulations are surprisingly high within the Great Barrier Reef Marine Park. More effective enforcement of zoning regulations and more effective community education programs are needed if the Marine Park’s multiple-use zoning plan is to successfully achieve its objectives of conserving biodiversity and long-term sustainable use.
Project 4.8.2 AIMS Cappo, M. et al. (2010) The influence of zoning (closure to fishing) on fish communities of the shoals and reef bases of the Great Barrier Reef Marine Park: Results of repeated surveys of the southern banks and Cardwell shoals, and an overview with regional comparisons
This report presents the results of repeated surveys of pairs of discrete 'shoals' off Cardwell in the north and on either end of the Capricorn shelf in the south of the Great Barrier Reef Marine Park. We also provide coarse regional comparisons of these results with 'snapshots' of mean and median abundances from shoal pairs in five other regions obtained during the four years of this project.
Project 4.8.2 AIMS Cappo, M. et al. (2010) The influence of zoning (closure to fishing) on fish communities of the shoals and reef bases of the Great Barrier Reef Marine Park. Complementary analysis of observations from divers and baited video surveys to quantify the influence of region, habitat and zoning, and extension of results to regional groups
Report Series No. 38 - Cappo, M., De'ath, G., Stowar, M., Johansson, C. and Doherty, P. (2009) The influence of zoning (closure to fishing) on fish communities of the deep shoals and reef bases of the southern Great Barrier Reef Marine Park. Part 2 - Development of protocols to improve accuracy in baited video techniques used to detect effects of zoning
Report Series No. 37 - Cappo, M., MacNeil, A., Stowar, M. and Doherty, P. (2009) The influence of zoning (closure to fishing) on fish communities of the deep shoals and reef bases of the southern Great Barrier Reef Marine Park. Part 1 - Baited video surveys of the Pompey, Swain and Capricorn-Bunker groups of reefs off Mackay and Gladstone
Report Series No. 6 - Speare, P. and Stowar, M. (2008) A comparative study between fished and protected inter-reefal shoal habitats and their fish communities on the Great Barrier Reef; Report on ongoing monitoring off Townsville and initial surveys near Cardwell and Cairns
Report by the Australian Institute of Marine Science, June 2008. Stereo Baited Remote Underwater Video Stations (SBRUVS) were deployed as part of a larger study of the fish communities of the Great Barrier Reef Marine Park in response to zoning changes by the Great Barrier Reef Marine Park Authority in 2004. This report assesses the use of SBRUVS as a tool for precise measurements of fish length to supplement comparisons based simply on visual observations of diversity and/or abundance.
This report presents the results of three to five return visits (between July 2006 and May 2008) to shoal grounds in the Cardwell and Townsville (North Queensland) regions of the Great Barrier Reef, comparing areas closed to fishing in 2004 with control areas that remain open to fishing. Fish abundance and species composition was established with baited video stations. Habitats were assessed by towed video camera and classified into broad categories of substratum and life form.
This report presents the results of seasonal surveys (Autumn/Spring 2007) on two pairs of discrete deepwater shoals in the southern Great Barrier Reef. Within each pair, one shoal was re-zoned 'Green' (closed to all fishing) in 2004 while the other 'Blue' (open to fishing) remained open to fishing. Each shoal or bank is a large submerged structure of several square kilometres rising from about fifty metres depth to within twenty to thirty metres of the surface. Demersal vertebrate communities were sampled using non-extractive baited remote underwater video stations, which revealed a diverse (~250 species) and abundant fauna of fish, sharks, rays and seasnakes including those targeted and not targeted by recreational and commercial line fishers.
Project progress report by P. Speare and M. Stowar, Australian Institute of Marine Science, on results of a baseline survey of 'green' zoned sites on Magnetic Shoal, together with non-green sites in the adjacent 'blue' zoned areas of the marine park initialised in July 2006. Ongoing monitoring was maintained in order to assess any seasonal effects on the fish and benthic communities. Output from Project 4.8.2 Influence of the Great Barrier Reef Zoning Plan on inshore habitats and biodiversity, of which fish and corals are indicators: Reefs and shoals.