Stretching between Mt Navotuvotu in the west, past Mt Kasi and towards Mt Sorolevu are large tracts of native forest. Beneath these canopies run crystal clear rivers and streams with abundant fish and invertebrate life. I led a small team to explore previously un-surveyed rivers and record the biodiversity found there. The team of 2 Fisheries Officers, aquatic ecology consultant Aaron Jenkins and I (WCS Fiji’s Freshwater Specialist) left Viti Levu by boat before the sun came up on 30th July, bound for the port of Nabouwalu at the southern tip of Fiji’s second largest island, Vanua Levu.
The team arrived in Nabouwalu and headed straight to Nakawaga village, part of the province of Cakaudrove. After presenting our i sevusevu to the village elders we were given the thumbs-up to undertake our biological assessments of the river fauna beside their village. The villagers assured us that we would find lot of life there, since the river had been protected for the last 10 years. After 4 hours surveying the river we had to conclude that this was not a healthy site: the impacts of upstream activities were really being felt, even in this protected stretch of river. Over a bowl or 2 of kava that evening, we reassured the village that it is still an excellent idea to have protected area in place, but if the communities cannot control upstream activities, then it would be wise to shift the protected area to somewhere they can restrict the surrounding activities.
The second site surveyed was the upper catchment of the Wainunu River where we stayed in the upstream village of Navakasali; we were the first visitors that they had had this year! Happily, the sites surveyed were of high water quality with diverse and abundant fish life. There was also high abundance of freshwater prawns; these related well to the traditional methods of catching prawns – the method involves lining up rocks in a V shape along the shallow edge of the stream and placing rotten coconut in the inner part of the V. At night they come and collect prawns by the hundreds from the V.
Our second day from Navakasali was much more disappointing. We surveyed Wailoaloa river near a forestry station. We pulled seine nets and hand nets through the murky water and caught nothing. It was completely lifeless; no fish, no prawns, no mollusks, not even any insects or insect larvae. The local village guides said that inhabitants of the forestry station would often use chemical fishing techniques (i.e. herbicides) to fish here and that is why it was so devoid of life. This was a stark contrast to the previous site we had visited. Further upstream the story was the same – years before herbicides had been used to clear the area before planting mahogany, and chemical fishing had been used frequently in this stretch of river.
We left Navakasali for Daria village – the Wainunu river which passes Daria originates right from the peaks of Mt. Navotuvotu. The site was a protected area (tabu) that stretched for 200m. Despite riverside gardening of dalo (taro), the water in the upper Wainunu was of high quality, with moderate fish diversity. We recorded high abundance of the endemic fish Redigobious leveri, with very large size fishes.
The last village visited was Driti village, in the upper reaches of the Dama River. The forest in these upper catchments was intact and healthy explained the high abundance native fish present. This site was a haven for gobies with four species including the relatively rare endemic Stiphodon isabellae, and abundant prawns.
To conclude, these surveys found the state of upper catchments to be very variable between sites. Often gardening, livestock and forestry have already impacted on the fauna within these upper catchments. The Dawacumu and upper Dama rivers possess the most unique biodiversity and intact fish populations, and the forests are in the best condition of the sites sampled. There is a clear need to do some awareness-raising on the impact of chemical fishing and herbicide use for clearing undergrowth prior to planting of timber trees. Both of these practices are having a severe impact on waterways in Fiji and even in some very isolated and remote upper watershed areas. These results will be presented back to communities in the coming months, as part of a project to identify riparian buffer zones and areas of native forest for protection.
This project is kindly supported by the Critical Ecosystem Partnership Fund (CEPF), a joint program of l’Agence Française de Développement, Conservation International, the Global Environment Facility, the Government of Japan, the John D. and Catherine T. MacArthur Foundation, and the World Bank.