A research cruise was conducted in the eastern Indian Ocean off west Sumatra, Indonesia, in June 2003 to learn about the spawning and larval ecology of the tropical freshwater eels of the genus Anguilla in the region. A total of 43 anguillid leptocephali were collected during the cruise and they were genetically identified as 41 Anguilla bicolor bicolor, 1 Anguilla marmorata, and 1 Anguilla interioris. A. bicolor bicolor leptocephali were 44.1-55.5 mm TL and most of them were at the fully grown stage. Reexamination of the historical data of Jespersen (1942) also suggested a relatively low abundance of small size leptocephali (<40 mm) of this species off west Sumatra. Although the study area has long been considered to be a spawning site of A. bicolor bicolor, the distributions of leptocephali from the two surveys and the patterns of ocean currents in the region suggest the possibility that the main spawning area of this species is located farther offshore.

Remarkably little is known about the life histories of the many tropical anguillid eels distributed across the Indo-Pacific region, and since the Danish expedition to study eels in the region in 1928 and 1929, research on these eels has only begun again in recent years. Sampling for anguillid leptocephali in the Indonesian Seas has been carried out recently to learn about the spawning ecology and larval distributions of tropical eels there. The leptocephali of Anguilla marmorata, Anguilla bicolor pacifica, Anguilla borneensis, Anguilla interioris, and Anguilla celebesensis were collected around Sulawesi Island both in May 2001 and October of 2002. The development of genetic identification techniques has enabled these leptocephali to be identified to species, and their distributions and sizes during different seasons indicated that there are differing life history patterns among sympatric species in the region. A. celebesensis was found to have been spawning in Tomini Bay of northeastern Sulawesi Island in March and April 2001, but apparently, no spawning had occurred in the late summer and fall of 2002. Studies on anguillid glass eels have suggested that tropical anguillids may spawn throughout much of year, but our research on leptocephali in Tomini Bay and data on the downstream migration of tropical anguillids in the major tributary to Tomini Bay indicate that A. celebesensis may have a distinct seasonal pattern of spawning possibly related to the regional monsoon cycles. This is the first evidence of seasonality of spawning in tropical anguillid eels whose life histories are only just beginning to be revealed.

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.

No abstract

An opportunity arose to obtain humphead wrasse Cheilinus undulatus specimens between 2006 and 2009 from Indonesia, the major source and exporting country of this species, making study on its early gonad development possible for the first time. Protogynous hermaphroditism, previously proposed for this species, was confirmed in this study. Based on histological examination of 178 specimens, mainly <500 mm total length (L(T)) and ranging from 208 to 1290 mm L(T) (119.1 g to 43.0 kg whole body mass), the minimum body sizes for female and male sexual maturation were determined to be 650 and 845 mm L(T), respectively. Primary male development through juvenile sexual differentiation was not detected. A unique blind pouch, with a possible sperm storage function and associated with the testis, was reported for the first time in the Labridae. In Hong Kong retail markets, the global trading centre for this valuable species, live C. undulatus on sale for food were dominated by body sizes <500 mm L(T) between 1995 and 2009, reflecting an international trade largely focused on juveniles. In consideration of these findings, and given the threatened status of this species, management for C. undulatus capture and trade nationally and internationally are discussed with recommendations for ensuring sufficient spawning biomass in exploited populations and for sustainable trade.