Rapid reproductive analysis and length–weight relation for red-bellied fusilier, Caesio cuning, and longfin emperor, Lethrinus erythropterus (Actinopterygii: Perciformes: Caesionidae and Lethrinidae) from a remote village in Papua New Guinea

We present length-weight relations (LWR) and use rapid, low-cost histological methods to describe the reproductive biology of the red-bellied fusilier, Caesio cuning (Bloch, 1791), and the longfin emperor, Lethrinus erythropterus Valenciennes, 1830, based on 137 and 139 specimens, respectively, collected from a remote area in Papua New Guinea. The LWR for C. cuning is W = 0.0208FL(3.0322). We estimate male L-50 at 12.6 cm FL and female L-50 at 15.3 cm FL. Overall sex ratio of mature individuals is not significantly different from 1 : 1; however, sex-ratio does vary with length. Females dominate size-classes from 17 through 20 cm and males are more abundant in smaller and larger size classes. The species is a batch-spawning gonochore. Batch fecundity is an exponential function of length BF = 0.1163FL(4.2796). The LWR for L. erythropterus is W = 0.0145FL(3.0976) for all specimens, but the length-weight relation differs between sexes. We estimate minimum size-at-maturity for males at 19.2 cm FL, and female L-50 at 20.4 cm FL. Overall sex ratio of mature individuals is not significantly different from 1 : 1; however sex-ratio does vary with length. Males dominate size classes >21 cm. The species is a batch-spawning, protogynous hermaphrodite.