In March 2009, after reports that a extremely long gill net covering large areas of reef on Phi Phi Ley Island was discovered, volunteers from a number of the dive centers headed out on the Reef Ranger on an attempt to remove it.
Prior to the dive, the team of 12 divers was split up into 3 groups and directed to each work on a different part of the net.
The gill net is a narrow net about 3 meters tall with weights along one edge and small buoys positioned along the other edge. The idea is that the net is extended across the seabed and the buoys suspend the net off the bottom so that fish and other marine life swim into it. The net is made of filamentous nylon line, which is almost invisible and will catch anything that swims into it. Gill nets can be hundreds of meters long.
Commencing the dive in the shallows we followed the net along and down expecting it to be not more than 15 meters deep. The net was entangled within the different colonies of corals and at 15 meters depth the fringing reef slope reached the sandy bottom. Following the net for over a hundred meters we decided at the depth of 25 meters that we could not follow it any deeper. Since we were well over the sandy bottom we resigned the remaining part of the net to the depths since it was not causing any damage to the reef and considering bottom time and air we would not be able to work on that part of it.
We started to snip and roll the net up, collecting into net sacks. Some divers were assigned to snipping, while some divers were assigned to collecting the segments. Only scissors were used since dive knives can cause damage while divers saw at the net. At that depth we were working in only 4 meters visibility so great care needed to be taken to avoid entanglement or injury from stinging organisms. It is quite common to find, scorpionfish, and stingrays entangled in these nets.
As we ascended to shallower depths the work became increasingly harder and slower due to the denser coral life in the shallows. This particular reef has a high concentration of acropora sp. corals and due to their branching forms, picking filamentous net is slow and awkward.
The dive was successful and we needed only a short second dive to remove the remaining net.
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Speedboat damage
Ironically, as we reached the surface we discovered a speedboat with a group of one-day snorkelers from Phuket. They had thrown a large anchor into the middle of an acropora colony, which caused a large amount of damage. Our request to remove and refrain from using anchors was met with laughs and shoulder shrugging.
On reporting this to the speedboat company, they surprisingly were very apologetic and assured us that this is not generally their policy and will try to take steps to avoid it in future. Usually the response is one of aggression and denial.
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Advice to divers on net removals
If you find a net on a regular dive do not remove it. If you do you will only encourage divers that are probably not equipped with either the right tools or the correct knowledge and they are likely to cause more damage, no matter how good the intentions.
Instead, make a good study of the net, the depth, an estimation of how much work, time and manpower it will take to remove. Remember, net removal costs money and that is usually privately funded, so a well laid plan and dive briefing can save money.
Return to the site on a day with little currents. This will improve the workload.
Prepare a careful brief. Allot each person a specific job.
Each person should be equipped with scissors even if they are not cutting. This is just in the event of entanglement. Use net bags to collect the debris. Do not use knives.
Work from the deepest point of the reef. As one diver snips another one should be rolling up the net.
Do not rush. Be prepared to do multiple dives if necessary.
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