Scientist studies sea cucumber's movements in PNG
Scientist to track movement of endangered sea cucumber in Papua New Guinea waters, as part of efforts to support local management of fisheries.
A marine scientist is to study the movements of the endangered sea cucumber in Papua New Guinea's Manus province, tracing the dispersal of its eggs and larvae.
Richard Hamilton, who works for the not-for-profit group the Nature Conservancy, says the marine animal has been severely overfished.
Mr Hamilton talked to Amelia Langford about his upcoming projects and the hope his work will support the case for local management of sea cucumber fishing.
RICHARD HAMILTON: Sea cucumbers are really highly sought after in the Asian markets both for food and for medicinal purposes and they form a very important component of rural incomes in Papua New Guinea and throughout the South Pacific. They have been really severely overfished all throughout their ranges and actually in PNG, we did a study up there in Bougainville in 2008 and we were able to show that sea cucumber abundance there has declined about 99 percent in 16 years. So at the moment in PNG there is a national export ban on the sea cucumbers, which has been in place for about five years and I guess part of the problem with those blanket bottom of the cliff management strategies is one, you put a lot of hardships on local communities which in these coastal communities are very reliant on that for a source of income and secondly, when you lift the ban which hasn't happened in the past five years you get these kind of boom and bust fisheries which operate below the maximum economic potential.
AMELIA LANGFORD: So with your work, are you hoping to work out a way to have a renaissance of this sea species?
RH: Yes, a couple of things have changed. The PNG national fisheries authority have recently reviewed their sea cucumber management plan, that was last year, that's one of the partners we work with in PNG, and under that revised plan the resource owners will be involved in the management. That's a change that was all top down prior to that. And also customary management measures, which are consistent with the management plan will be encouraged. So one of our key goals for this year, is to undertake scientific studies that we hope will support the case of community and local management of sea cucumber fisheries.
What we really want to do is see how far the pelagic eggs and larvae of sea cucumbers are dispersed because if the larvae aren't going far then it makes really good sense to manage these fisheries at fairly localised scales and what we plan to do is work with multiple partners to collect DNA samples from thousands of adults and juvenile sea cucumbers across about 100 kilometres of coastline in southern Manus in PNG.
AL: Wow, so it is quite an ambitious project isn't it?
RH: Yeah, we've done it before but [this time] what we will be using is genetic fingerprinting methods to link the juveniles back to their parents and in this way we are able to determine where the eggs of the higher value sea cucumbers actually end up and to date nobody has ever examined larval dispersal in sea cucumbers but we've had these recent technological developments in genetic parentage analysis and that means that is now possible. And a couple of years ago in Manus, in PNG, we used this method and we were able to show that for coral trout, larvae which is spawned at a spawning aggregation site, about 50 percent of the larvae settled less than 14 kilometres from their source - where they were born - and if you think about that in terms of how far larvae travel, that's basically a magnitude less than what marine biologists were thinking was the case a decade ago. They used to think this larvae was fairly passive and they just went hundreds of kilometres with the currents. But what all this means is it's really good news, if you've got local retention of larvae, it's good news for community based management because it shows local efforts result in local benefits so in a fisheries sense, if you manage some of your areas by protecting them the large number of juveniles produced in those protected areas will replenish nearby open fished areas.
AL: You mention genetic fingerprinting - how does that work?
RH: It is essentially, with the microsacs, you can actually, if you sample a whole lot of adults and then you sample a whole lot of juveniles you can cross-check all the adult population against all the juveniles and you can actually see what juveniles you can link back to one or two parents. So you can see how far they've dispersed.
AL: Oh that's amazing.
RH: Yeah it's a pretty new technology but it's really revolutionising what we call connectivity, that understanding of how far things actually go. Because in these marine systems where you have this pelagic larval stage where the eggs and the larvae float around in the ocean for four or five weeks, prior to about five or six years ago we really had no idea of how far this larvae was going. But, a lot of the studies are showing that a lot of this larvae is retained very close to source which is very good news for community based management. Basically, you get the benefits of your efforts, if you like.
AL: Apart from that you're busy looking into the nautilus?
RH: That's a new project. It's something I haven't been involved in before but it's going to be based in Manus province in Papua New Guinea. The work we're looking to do with that is funded by the National Geographic Society. It'll involve making population estimates with nautilus in about 200-700 metre deep range in southern Manus. We do this using baited underwater camera systems which operate up to about 15 hours.
AL: A lot of people think of Manus Island these days, they think of the detention centres and the asylum seekers there. Does Manus Island also have other claims to fame such as a beautiful natural environment?
RH: Manus Island is located in the coral triange, which is the epicentre of biodiversity for the globe. You've got two percent of the world's seas containing 75 percent of all the coral and fish species on Earth. Manus coral reef systems are very pristine. You've got a fairly low population, quite extensive reef systems, and probably some of the nicest coral reef anywhere in the world really. So we've been working there for quite a long time with a fisheries management conservation project. It's a very beautiful part of the world. We do all our field work based on large out-rigger canoes, we live out on the water for a couple of weeks on them. It's a lot of fun, we're often anchored out on the reef for several weeks at a time and working very closely with a lot of local fishermen. So it's very social but you don't have a lot of space.
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