Rapid assessment of coral reefs around Koro Island, Lomaiviti Province
Nand, Yashika;Mangubhai, Sangeeta;Naisilisili, Waisea;Tamanitoakula, J.;Sirilo, Dulunaqio
Access Full Text
Koro Island is north of Suva in the Lomaiviti Province and is the sixth-largest island in Fiji. There are 14 traditional fishing grounds and at the time of the study, there were 7 tabu areas (periodically harvested closures). On 20 February 2016, one of the largest cyclones on record in the southern hemisphere passed through Fiji, leaving a trail of destruction, with some of the most impacted landscapes and communities located in the Vatu-i-Ra Seascape. A detailed assessment of community fishing grounds (qoliqoli) around Koro Island in the Lomaiviti Province was conducted from 6−12 September, 2017. The objectives of these surveys were to: (a) document the overall health of coral reefs around Koro Island; (b) assess impact and recovery of coral reefs within community fishing grounds 18 months after Cyclone Winston; and (c) provide recommendations to communities on the management of their traditional fishing grounds to maximise post-cyclone recovery, and support ridge-to-reef planning and implementation for Koro Island. Data were collected on the benthic cover, habitat structure, and fish size and abundance. Surveys were done both inside and outside tabu areas within community fishing grounds. A total of 31 sites were surveyed, of which, 14 were previously surveyed in 2013 and 2014. Sites surveyed were from exposed and sheltered sides of the island within reefs protected (tabu) and open to fishing. WCS had pre-cyclone data from two fishing grounds (Tuatua and Nakodu); however, the data was collected immediately after a tabu harvesting event which made it difficult to differentiate the impact of the cyclone and the recovery potential of reefs. However, trends in benthic cover and composition and fish assemblages from the two fishing grounds, and overall data collected on the reef system around Koro Island, is still useful to communities making decisions on their natural resources. The benthic composition differed between exposed and sheltered sites of Koro Island; exposed sites showed more signs of cyclone damage, while sheltered sites showed more signs of disturbance such as sedimentation from the land1. Unconsolidated substrate was the most dominant benthic substrate observed (average = 29.0±21.4%), and coral cover averaged 8.4±4.9%. A high number of fish species (165 spp.) was recorded during the survey. Fish biomass was highly variable ranging from 158.7 kg/ha to 3347.3 kg/ha; however the average fish biomass was 1299.0 kg/ha indicating stocks were generally healthy. These results suggest that some reefs around Koro Island are in good health while others are struggling to maintain functional levels of fish biomass. Although only a few whitetip and blacktip reef sharks were observed, the study recorded several families of important functional groups of fish species such as siganids (rabbitfish), lutjanus (snappers) and serranids (groupers). This study found that the majority of reefs had not recovered from the impact of Cyclone Winston. Tuatua and Nakodu fishing grounds showed a decreasing trend in coral cover, an increase in fish biomass, but a decline in fish species richness.