LENGTH-WEIGHT RELATIONS OF 14 ENDEMIC FISH SPECIES FROM THE UPPER YANGTZE RIVER BASIN, CHINA

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.

pronounced habitat heterogeneity and considered a biodiversity hot spot for fish conservation (Dong 2003). There are about 286 species and subspecies including 124 endemic species distributing in the upper Yangtze basin (He et al. 2011).
In fish biology, length and weight are two basic morphological traits at the individual-as well as at the population level. The weight of fishes is closely related to their length, and there are three somatic growth types for most fish species: isometric (all fish dimensions increase at the same rate), positive allometric (a fish increases more in weight than predicted by its increase in length) and negative allometric (a fish increases less in weight than predicted by its increase in length) (Froese et al. 2011). Length-weight relation (LWR) has been used widely for fishery management and conservation. It provides information on the condition factor and somatic growth type (isometric or allometric) of fish species (Le Cren 1951, Bagenal and Tesch 1978, Bolger and Connolly 1989. It enables the calculation of individual weight from its length, estimating age structure, weight growth rate, and stock assessment. This relation has also been used for comparison of species growth between sexes, different seasons and regions (Froese 2006). Up to now, LWRs of 3584 species can be checked in FishBase (Froese and Pauly 2012) Our current knowledge on the biological traits of Chinese freshwater fishes is still very limited (Fu et al. 2003). In particular, LWRs are only known for some commercially important fishes such as: Cyprinus carpio L.; Carassius auratus (L.); Ctenopharyngodon idella (Valenciennes, 1844); etc. In this study, we estimated the LWR parameters for 14 endemic fish species collected from the upper Yangtze River and its tributaries. Also, to the best of our knowledge, this study presents the first reference on the LWRs worldwide for these species.
The collections were made periodically between October 2011 and July 2012 in the mainstream of the upper Yangtze River and its seven tributaries. Three types of fishing gear were used in the sampling course, gill net (1.5, 4, 5, and 5.5 cm mesh), trap, and longline hooks. Sampled fish were identified to species according to references (Ding 1994, Yue 2000, and then measured to the nearest 0.1 cm standard length (L), weighed (W) with a digital balance with the accuracy of 0.1 g. Length and weight data were pooled together in each species without

LENGTH-WEIGHT RELATIONS OF 14 ENDEMIC FISH SPECIES FROM THE UPPER YANGTZE RIVER BASIN, CHINA
sexing or discrimination as to sampling sites and time.
A log-log plot of data was done for all species; outliners were identified and removed (Froese 2006). The parameters a and b of relations of the form W = aL b were estimated through a logarithmic transformation (Tesch 1971, Cone 1989, i.e., log W = log a + b log L Intercept a and slope b were estimated by ordinary least squares regression and 95% confidence limits of a and b were calculated. The b-value was tested by t-test to check whether the growth of each species is isometric (b = 3), positive allometric (b > 3) or negative allometric (b < 3).
A total of 3782 specimens covering 2 families, 10 genera, and 14 species were caught from upper Yangtze River and its tributaries. The species studied were:  Fang, 1942;and Xenophysogobio boulengeri (Tchang, 1929) Thirty two outlines were excluded according to the log-log plot, and regressions were made for a total of 3750 individual fish specimens. The species name, sample size (n), length and weight ranges, intercept a, slope b, 95% confidence interval of a and b, coefficient of determination (r 2 ), growth type and t-test value were summarized in Table 1.
The somatic growth of fishes is influenced by a number of factors such as sex, gonad maturity, growth phase, season, and stomach fullness (Tesch 1971 (Froese et al. 2011). In this study, sample size of most specie (except Jinshaia sinensis and Acrossocheilus monticola) were above 100, and measured individuals covered juveniles to adults, thus, the LWRs results of these 14 endemic fishes were credible and served as baseline data for endemic fishes management and conservation.