Dealing with overfishing and destructive fishing practices are a huge issue for marine conservation and management. Tackling this problem, and trying to repair some of the damage is no easy task. We know that if they are done properly, no-take marine protected areas can make an impact, not only reducing habitat degradation by removing damaging fishing techniques, but also increasing the density and even the individual size of species targeted by fisheries. The benefits these no-take zones provide can spill over to fishers too. And that’s not just a scientist point of view either – take a look at this short (5 minute video) focusing on lobster potter Geoff Huelin who fishes around Lundy Island – the UK’s first no-take zone.
There are many factors that can make or break a no-take zone. In the video Geoff touches on just one of those factors – policing the zone to make sure that people are abiding by the regulations. This is important. It’s no good having regulations to protect an area from fishing if fishing happens there anyway. It is the action of people – not the designation itself per se, that makes an appreciable difference to marine biodiversity recovery. Geoff tells us that for the Lundy Island no-take zone enforcement isn’t a huge challenge because the no-take zone is viewable from the shore. There is, Geoff tells us, usually somebody watching. But this can’t be said for all no-take zones. It’s not just distance from the shoreline that can impact on enforcement capabilities. Lundy’s no-take is small. Some no-take zones are huge, and very often manager’s budgets and resources are limited. Take the Great Barrier Reef Marine Park for example, which suffers hundreds of infringements of its regulations each year. Sure both commercial and recreational fishers who break the regulations inside the Park are successfully caught every year using a host of different surveillance techniques, but many more are likely to go unnoticed. Getting a handle on the scale of non-compliance is the very issue explored in this recent paper by David Williamson from the ARC Centre of Excellence for Coral Reef Studies and fellow researchers.
The research team focused their efforts on several fringing coral reefs in the Great Barrier Reef Marine Park – those around the Palm Islands, the Whitsundays, and the Keppel Islands. You may have heard of these places. Beautiful and fairly accessible from the mainland, these areas are popular with tourists and locals alike. Although all managed by the Park authority, the fringing reefs around these Islands aren’t all no-take, and the Aboriginal people’s of the Palm Island group have fishing and hunting rights across the whole Park – including inside the no-take zones. The researchers needed a way to estimate fishing effort inside the no-take parts of these reefs, and for this they needed some evidence… evidence in the form of derelict fishing line from hook and line fisheries. The first thing to do was to calculate the density of derelict fishing line both inside the no-take zones and outside. So in the water they went and surveyed the derelict line. Some statistical analysis later, and the team had an estimate of hook and line fishing activity both in and outside no-take zones on the reefs across the three island groups.
In the Whitsundays and the Palm Island, the no-take zones that had been around for over 20 years had the lowest density of fishing line within them compared to zones established 5 years before the surveying, and ‘normal’ sites. Interestingly no-take zones that had been established for only 5 years didn’t show any significant difference in line density when compared to ‘normal’ sites. But fishing line is typically made from hardy stuff, and doesn’t easily break down. The researchers note that 99% of the fishing line found had accumulated algae and sessile organisms on them, and/or become partially embedded in the reef matrix itself. This indicates that most of the line had been there for months or even years, but ascertaining just how long is difficult. Some of the line likely was there prior to establishment of the no-take zones but just how much… well that is a difficult question to answer.
The team did not stop with simply working out the density of fishing line though. Around the Palm Islands the researchers used the assistance of Reef Check Australia – a citizen science organization that is heavily involved in marine monitoring – to remove derelict fishing line from both no-take zones and monitored the sites to see just how quickly fishing line accumulated in the no-take zones and in the areas outside them for some 3 years. Here the rates of line accumulation between the no-take zones and the other cleaned ‘normal’ sites were, statistically speaking, “marginally non-significant”. In arguably more real terms, the researchers note that the rate of fishing line that accumulated inside the cleaned no-take zones was 32.4% of that accumulated inside the ‘normal’ cleaned sites. And 32.4%, say they researchers, is worrying for a zone that is supposed to be a no-fishing area. But what about those Aboriginal fishers that have a right to fish inside the no-take zones – couldn’t some of the line be from them? Well yes, though the authors note that at least from personal observations not all of the no-take zones they cleaned and monitored were regularly used by Aboriginal fishers. What all this points to, the researchers argue, is that non-compliance with no-take zones isn’t just an issue in the more remote parts of the Great Barrier Marine Park. They also note that when assessing how effective a no-take zone is in restoring marine biodiversity, it is worth taking into account the level of non-compliance with regulations as best one can.
This paper (including an open access link to their data) was published in the open access journal PLOS ONE. You can read it here http://dx.doi.org/10.1371/journal.pone.0114395
Image: The Whitsundays. Credit Richard Rydge/Flickr (CC BY-NC-ND 2.0)