By Andrew Darby
As Australia's recreational fishers head out this summer to wet a line, there's a warning for those tempted to poach in no-take marine reserves ??? your signature may be left behind.
Survey work on the Great Barrier Reef has found derelict fishing lines snagged on coral are a yardstick for the level of poaching.
Surprisingly high levels of fishing still take place in these reserves, according to the study in the international journal PLOS-One, and derelict lines can tell authorities which areas need policing.
Recreational fishing is a multibillion-dollar leisure industry, with more than 5 million Australians taking part, according to the Australian Bureau of Statistics.
No-take reserves have been designated around the country to protect important marine communities, but 96 per cent of all federal waters within 100 kilometres of the shore is still open to recreational fishers, according to a University of Technology, Sydney, study.
State waters run from the shoreline out to 5.5 kilometres, and about 5.3 per cent of Victoria's marine territory is no-take sanctuaries; in New South Wales it is 8 per cent.
James Cook University scientist David Williamson said well-protected no-take reserves not only helped restore fish and surrounding habitat, they allowed a "spillover" to surrounding fished areas. But these gains could quickly be eroded if compliance from fishers broke down, Dr Williamson said.
On the Great Barrier Reef, non-compliance with no-take reserves has been a long-standing problem, with hundreds of infringements by commercial and recreational fishers recorded annually.
"Given the enormous size of the [reef marine park\, the remoteness of much of it, and the limited resources allocated to surveillance and enforcement, it is highly likely the recorded infringements represent a small proportion of the total," he said.
With the aid of dive teams, Dr Williamson surveyed 94 sites in a series of no-take reserves at reef islands, including Palm Islands, Hayman, Whitsunday, and the Keppels, where marine life is critical to tourism. The divers went looking for fishing lines, hooks and sinkers snagged and lost on the coral, and cleaned up 10 sites, before returning 32 months later to recheck them. They found hundreds more lines tangled in coral in no-take reserves, particularly if the reserves were only a few years old.
"In the worst sites, we found derelict line was reaccumulating at the rate of 51.2 pieces of line per hectare per year. It's a lot of pressure on the reserve. That stuff can last for decades, and entangle marine life such as turtles."
In the Palm Islands, a small amount of the no-take reserve fishing was by indigenous people with a right to the waters, he said. "But the vast majority is actually strategic poaching by mainly recreational fishers, who either don't care or are not aware they are in a reserve."
Dr Williamson said although this study focused on the Great Barrier Reef, the findings had global relevance. Removing derelict fishing gear and monitoring its reaccumulation was a useful means of finding where fishers went, and detecting their intrusion into no-take reserves.
This could help community education programs and improve marine park surveillance patrols, and in assessing whether the fishlife was improving.