Mussau Island in New Island Province lies 160 kilometres north of Kavieng and is well known for having a large population of green turtles.
However, recent surveys by WCS have found turtle densities around the island to be highly variable.
Two villages, Nae and Lolieng, are separated by just 33 kilometres of coastline have very different turtle densities. For example, the reef crest at Lolieng supports an average of 7 turtles per hectare whereas the same habitat at Nae has only 0.2 turtles per ha.
Azalea Anota, a research intern at WCS working on the turtles describes the situation.
“Not only are the number of turtles between the two areas very different but so is their behaviour. Turtles in Nae have been persecuted for various reasons and not surprisingly their numbers are much lower, and as a result the turtles in this area also have adopted very specific behaviours not seen in the other community such as only coming into the lagoon area at night when there are fewer people around”.
The disappearance of sea grass beds and an edible seaweed species (known locally as “goru”) has made locals concerned with many suggesting the turtles are to blame.
Nathan Whitmore, a scientific officer with WCS, is doubtful of the connection.
“Actually scientific evidence suggests the reverse, namely that green turtles, actually help to maintain healthy seagrass beds. In fact, we know die offs of green turtles have been directly linked to the death of seagrass beds around America. We shouldn’t forget that according to Mussau locals the number of turtles was already dropping at the very same time the lagoons started to lose seagrass and goru”
Azalea Anota, who is leading research on the turtles elaborates, “At this stage we are looking at the seagrass and goru decline from a number of different perspectives including the possible impacts from the increased irregularity of the north-west monsoon, whether the depth of the lagoons has decreased due to uplift caused by earthquakes, as well as human impacts on goru harvesting, turtle populations, and reef health.”
Nathan Whitmore adds, “Green turtles are disappearing from the world’s oceans but it is clear that the sea around Mussau Island can still support large numbers of turtles today. For this reason the area is of regional significance not just in PNG but Melanesia. But at this stage the future of the turtles is not guaranteed”.
WCS is currently working with the local communities to understand the relationship between Green turtles, people, seagrass and goru in a two year project funded by the Critical Ecosystem Partnership Fund.