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Since two large specimens of Chinese paddlefish Psephurus gladius were found unexpectedly in December 2002 and January 2003, a series of measures have been undertaken to attempt to save this critical endangered species. As a part of the rescue plan, a total of eight hydroacoustic and capture surveys were conducted in the upper Yangtze River between 2006 and 2013. Preliminary results from the first four surveys (2006-2008) were reported in 2009. The later four surveys were conducted in the same area and consisted of 578 setlines, 8 anchored setlines and 2003 drift net catches. A total of 1982 fish belonging to 38 species were captured. For the hydroacoustic surveys, a BioSonics echo sounder with a vertically down looking 199 kHz split-beam transducer was applied, both for data recording, and for guiding the capture trials by drift nets and setlines. Post processing applying automatic tracking identified 7217 single targets from the eight acoustic surveys. Body size was estimated from TS values of single targets. No P. gladius were captured. The acoustic data, however, revealed at least a few observations that are difficult to interpret as something other than large P. gladius. Although not conclusive, this gives hope that this species may still exist in the river. [ABSTRACT FROM AUTHOR]

Results from previous research suggested that geomorphic characteristics may be important controlling factors among other microhabitat variables for spawning fish. We investigated the bedform morphology of seven spawning areas (five historic and two present spawning areas) of Chinese sturgeon ( Acipenser sinensis) by analysis of relief maps of the riverbed and by field surveys. We conclude that the topographic characteristics of the spawning areas include rocky or gravelly substrate river bend, large variations in water depth and river width and a slope with moderate length and slope. The turning structure and the adverse slope may be the most important topographic characteristics for the spawning areas. Combined with the reproductive occurrence of the fish in these spawning areas, we tentatively propose a bedform morphology hypothesis for the spawning areas. We consider that a spawning area of A. sinensis should consist of three functional areas: Mating area (M), Dispersal area (D) and Incubation area (I). M, D and I are distributed along the water current and their bedform characteristics are clearly different. M is the place for mature fish to mate and spawn. It is usually below a riffle with rolling terrain. D is the place for fertilizing and dispersing fertilized eggs. It is usually in a river bend with sharp variations in terrain, such as deep pools or steep slopes. I is the place for dispersal of fertilized eggs. It is usually in long point bars or broad shallow areas with rocky substrate. This hypothesis could serve as a guideline for improving the present spawning areas or constructing new spawning areas, so as to rehabilitate the wild stock of the sturgeon. [ABSTRACT FROM AUTHOR]

Length-weight relations were estimated for 14 endemic fish species of the upper Yangze River, namely Sinogastromyzon szechuanensis Fang, 1930; Jinshaia sinensis (Sauvage et Dabry de Thiersant, 1874); Megalobrama pellegrini (Tchang, 1930); Coreius guichenoti (Sauvage et Dabry de Thiersant, 1874); Rhinogobio cylindricus Günther, 1888; Rhinogobio ventralis (Sauvage et Dabry de Thiersant, 1874); Procypris rabaudi (Tchang, 1930); Ancherythroculter kurematsui (Kimura, 1934); Ancherythroculter nigrocauda Yih et Wu, 1964; Acrossocheilus monticola (Günther, 1888); Leptobotia elongata (Bleeker, 1870); Hemiculterella sauvagei Warpachowski, 1888; Hemiculter tchangi Fang, 1942; and Xenophysogobio boulengeri (Tchang, 1929). The a values obtained ranged from 0.006 to 0.023, and b values ranged from 2.955 to 3.377. The t-test results indicated the first seven species grew isometrically and the other 7 species grew allometrically. [ABSTRACT FROM AUTHOR]