The Chinese sturgeon, Acipenser sinensis, is an anadromous species that spawns in the Yangtze River and Pearl River of China. Its population has declined dramatically since the construction of the Gezhouba Dam (GD) in 1981 and then with the impoundment of the Three Gorges Dam (TGD) upstream of the GD in 2003. This paper presents a quantitative method based on the instream flow incremental method to explore the relationship between the fish spawning habitat and the operations of the GD and TGD, aiming to find a solution for conservation of the species. A two-dimensional hydrodynamic model was built with the River2D to simulate the hydraulic behaviour of the stream below the GD. Habitat suitability index was determined by the biological data of the fish collected in the field. The two parts were then integrated through a geographical information system developed via ArcGIS to outline the fish habitat area variation with flows. The decision support system is applied to set up a habitat time series for validating the assumption that more habitats have the potential to support more fish. The fish habitat results for alternative instream flow schemes are then compared with one another for defining the optimal flow requirements and evaluating effects of reservoir operation alternatives in order to improve the operation management for the GD and TGD projects. The results show that the optimal flow for spawning of the fish is about 7000-13000 m 3 /s and the optimal inlets combination is where the inflow comes from two power plants.

The genus Sarcocheilichthys is a group of small cyprinid fishes comprising 10 species/sub‐species widely distributed in East Asia, which represents a valuable model for understanding the speciation of freshwater fishes in East Asia. In the present study, the molecular phylogenetic relationship of the genus Sarcocheilichthys was investigated using a 1140 bp section of the mitochondrial cytochrome b gene. Two different tree‐building methods, maximum parsimony (MP) and Bayesian methods, yielded trees with almost the same topology, yielding high bootstrap values or posterior probabilities. The results showed that the genus Sarcocheilichthys consists of two large clades, clades I and II. Clade I contains Sarcocheilichthys lacustris, Sarcocheilichthys sinensis and Sarcocheilichthys parvus, with S. parvus at a basal position. In clade II, Sarcocheilichthys variegatus microoculus is at a basal position; samples of the widespread species, Sarcocheilichthys nigripinnis, form a large subclade containing another valid species Sarcocheilichthys czerskii. Sarcocheilichthys kiangsiensis is retained at an intermediate position. Since S. czerskii is a valid species in the S. nigripinnis clade, remaining samples of S. nigripinnis form a paraphyly. This speciation process is attributed to geographical isolation and special environmental conditions experienced by S. czerskii and stable environments experienced by the other S. nigripinnis populations. This type of speciation process was suggested to be very common. Samples of Sarcocheilichthys sinensis sinensis and Sarcocheilichthys sinensis fukiensis that did not form their own monophyletic groups suggest an early stage of speciation and support their sub‐species status. Molecular clock analysis indicates that the two major lineages of the genus Sarcocheilichthys, clades I and II diverged c. 8·89 million years ago (mya). Sarcocheilichthys v. microoculus from Japan probably diverged 4·78 mya from the Chinese group. The northern–southern clades of S. nigripinnis began to diverge c. 2·12 mya, while one lineage of S. nigripinnis evolved into a new species, S. czerski, c. 0·34 mya.

The pharyngeal tooth remains of crucian and common carp from the Tinaluoshan site of the Hemudu CulturalStage, Zhejiang Province, China, were analysed. The body-lengths (BLs) of the fish were estimated from tooth size and plotted as bar diagrams. Based on these, we infer that Neolithic dwellers used gill nets to efficiently catch fish of a specific size during the breeding season. The BL distribution of common carp there is similar to those from Jomon sites in Japan, and we therefore infer that the technology for controlling water for rice cultivation in paddy fields had not yet been developed. The abundance of tooth remains of crucian carp unearthed at the Tianluoshan site is reminiscent of similar finds in Western Japan, and we thus infer that the culture trait of utilizing crucian carp as a major protein resource was distributed from the Yangtze River basin to Western Japan. Analysis of pharyngeal tooth remains of carp at various Japanese archaeological sites shows that freshwater fishing was conducted quite differently before and after the establishment of paddy fields. With this fact in mind, one of the present authors tried to model the development of freshwater fishing, with reference to the relation of fishing to rice cultivation (Nakajima, 2010). In Phase I, artisanal fishing became an active and technically developed endeavour, and people began to cultivate rice at fishing site. In Phase II, people began to cultivate rice purposefully in irrigated paddy fields while also fishing there. Comparing the present results of the pharyngeal tooth remains from the Tianluoshan site with those from the Jomon Period, we see that the Tianluoshan site was in the same stage as the end of Phase I in Japan, which rice cultivation was done as a supplementary activity at fishing site.