Quantifying the rare: Baselines for the endangered Napoleon Wrasse, Cheilinus undulatus, and implications for conservation

Abstract

Abstract The Napoleon wrasse, an endangered fish (Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) Appendix II, 2004), is a valuable component of the Chinese live reef fish trade. Only Indonesia legally exports up to 2000 Napoleon fish annually, with each fish weighing between 1 and 3 kg. Information on natural abundance and fish sizes was required to determine sustainable export quotas. Hence, an underwater visual survey method, using GPS‐based multi‐kilometre transects, was tailored for this uncommon wide‐ranging fish. Transects totalling 430 km were run between 2005 and 2016 at nine locations. Six locations were resurveyed between six and nine years later, which was long enough to allow for recruitment and maturation. Fish density and sizes across locations were inversely related to fishing intensity, and densities increased significantly between surveys. Low density (0.04‐0.86 fish hectare‐1) and few adult‐sized fish were in heavily fished locations. Higher densities occurred (0.86‐4.0 fish hectare‐1) in lightly/unfished locations, where evidence of recruitment was also seen. Nowhere were many male-sized (>1 m long) fish present. At Karas Is., where fishing ceased between surveys, clear sign of recovery was seen after 9 years. Comparison of survey data from 11 Indo‐Pacific countries indicated that in Indonesia adult densities were lower at comparable levels of fishing pressure than elsewhere. Densities of 5 fish hectare−1 or more are more typical of lightly fished or unfished areas across the Pacific, which is greater than the highest density of 4 fish hectare−1 noted in this study at Banda Islands. Low densities of the species, despite the presence of adult‐sized fish, in Bunaken Marine Park probably reflects the continuance of fishing both within and adjacent to the park. Conservation options include improved implementation of CITES regulations by Indonesia, through tighter export controls and the tagging of legally exported fish, the activation of the National Plan of Action, a temporary moratorium to restore reproductive capacity, and more marine protected areas.