utterfly Bay is a popular anchorage in the Whitsunday Islands. Underwater surveys carried out in 1996 indicated that illegal fishing was occurring regularly in West Butterfly Bay (based on the amount of snagged fishing line) and that refuse was also a problem. Butterfly Bay is zoned Marine National Park 'B', where fishing is not allowed. Marine Park regulations also state that 'rubbish cannot be thrown overboard in any zone within the Marine Park'.

Ongoing assessments of refuse levels and illegal fishing have been carried out in West Butterfly Bay during the last three years. These assessments have also included an annual underwater clean-up. The clean-ups have been performed in conjunction with a local community group: the Order of Coral Underwater Heroes (OUCH) Volunteers. On other occasions, fishing line and refuse have been removed (and documented) from replicate bommies at West Butterfly Bay and nearby Stonehaven Bay.

Methods

An underwater clean-up of West Butterfly Bay was carried out on 28 October 1996, 29 January 1998 and 23 November 1998. All refuse items, including fishing line, were documented once removed from the water. The cumulative dive-time cleaning the reef was recorded to determine the overall effort required to collect the refuse.

In October 1996 and January 1998 the clean-ups were carried out in an area approximately 300 metres by 100 metres. This area was haphazardly searched and there were sections (during both clean-ups) that were not cleaned as visibility on the bottom was low (< 2 metres to 3 metres). In November 1998, due to the instalment of seven new public moorings in the bay, a different search method was used. Divers from OUCH searched the bottom around each of the seven public moorings, using a swim-circle search technique out to 20 metres from each mooring (0.125 hectares were searched at each mooring).

Four replicate bommies in both West Butterfly Bay and North Stonehaven Bay have been established as fixed monitoring sites. These eight bommies have been surveyed at least three times over the last three years (Malcolm 1999). Fishing line and refuse was recorded and removed from each bommie during each survey to assess accumulation rates.

Results and Discussion

Refuse
Refuse in West Butterfly Bay has been an ongoing problem (table 1) throughout the duration of the survey period.

The results show a minimal reduction in the number of refuse and fishing items in most categories between 1996 and 1997-98 and the latest clean-up in November 1998.

Figure 1. An example of refuse collected on 29 January 1998 (18 diver hours)

A number of items (besides fishing line) were abundant during all three clean-ups; beer cans, stubbies and wine bottles; material items (especially towels and clothing); swim fins; and cooking items (figure 1).

The refuse recovered from the bottom appears to be a combination of intentional littering by throwing items overboard, and items that have probably been dropped or blown overboard by accident. The lack of plastic items, including plastic bags, suggests the recovered refuse is the component which sinks more readily. Substantially more items may be ending up in the water than indicated by these clean-ups. This combination of intentional littering and lack of due care is polluting the Great Barrier Reef Marine Park at this location.

One area of concern in a coral reef environment is that of submerged clothing or materials. Clothing can wrap around the coral and smother it by cutting out light and water circulation. The wrapped material also traps silt, further smothering the coral and eventually killing it. Recent coral mortality from smothering by material has been observed a number of times in West Butterfly Bay (pers. obs.). Of particular concern is the apparent increase in the number of material items (especially T-shirts and towels) recorded between 1996 and 1998.

Illegal Fishing
The amount of snagged fishing line cannot be used to determine actual fishing effort. However, it can provide a relative indication of effort, albeit a very rough indication. Comparable fishing effort between adjacent bays (with similar benthic habitat) may be indicated by similar amounts of fishing line being snagged within each bay. Continued fishing pressure may be indicated if fishing line accumulates at a similar rate from one year to the next.

West Butterfly Bay is a Marine National Park 'B' zone where fishing is not permitted and, as such, there should be no fishing line in this bay. However, during each clean-up a large number of snagged fishing lines have been removed. Some of the fishing line recovered was also old, which means the figures (table 1) do not represent accumulation over a set period of time or in a set area. However, a reasonable proportion of the recovered refuse was fresh line and hooks (i.e. line that had recently been snagged). Similar amounts of diver effort to recover refuse were expended on the first two clean-ups (approximately 18 diver hours), with slightly less diver effort on the November 1998 clean-up (approximately 14 diver hours).

This indicates that illegal fishing has been ongoing in this bay at a substantial level, and this is supported by the monitoring of replicate bommies.

The amount of fishing line removed from the four monitoring bommies in West Butterfly Bay in November 1998 was comparable with the previous amounts of line that had been removed from those bommies in October 1997 and June 1998 (figure 2), when the shorter period of accumulation is considered. This suggests that the level of illegal fishing activity has not decreased over the last three years in this bay.

Figure 2. Mean number of fishing lines per bommie (where n = 4 bommies) in North Stonehaven Bay and West Butterfly Bay October 1997, June 1998, and November 1998 (+ standard error around the mean).

Although snagged fishing line does not represent fishing effort, the above results suggest that levels of fishing in West Butterfly Bay (where fishing is not permitted) may have been as high or higher than North Stonehaven Bay (where fishing is permitted). Similar levels of fishing line were recorded in West Butterfly Bay and North Stonehaven Bay in October 1997 and November 1998, with more line recorded in West Butterfly Bay in June 1998.

Overall, the combined results from the refuse clean-up and the fixed site monitoring show that marine park zoning has been disregarded by a number of visitors to West Butterfly Bay. These results suggest that where there are higher levels of use, there will probably be higher levels of non-compliance with 'no take' zoning, at least at this location. This has wider implications regarding the effectiveness of zoning in particular areas within the Marine Park, unless this is a unique case.

Reference Malcolm, H. 1999, High use abuse: An example of an ongoing refuse and illegal fishing problem at a popular anchorage in the Great Barrier Reef Marine Park, Unpublished draft final technical report to Queensland Department of Environment and Heritage, January 1999.