Studies On Age And Growth Of Schizothorax Waltoni Regan

Schizothorax waltoni Regan is an endemic fish of the Tibet and mainly inhabits the Yarlung Zongbo River. From October 2003 to September 2004, 170 specimens collected from the lasha River were used for studies on aging, age structure, growth.Annual rings on opercular, vertebra, otolith, scale were detected on 170 individuals. Using RSS (Residual Sum of Square) and rate of agreement as index. Analyzing the accuracy of age observing result, von Bertalanffy growth equation was applied to formulate their growth characteristic. Data were analyzed with SAS analysis software. The following are the main results.1. Age of Schizothorax waltoni Regan(1) Otolith could be used for aging the fish efficiently. It can accurately determine the age. Annual rings on otolith and vertebra are almost equal. Befor age 7, the rate of agreement between otolith and scale as well as opercular is almost fit. After age 8, the rate of agreement of scale is very low.(2) The commercial catch consisted of ten age groups (age 2 to age 11) and individuals of age 4 to age 6 groups were dominant, occupying more than 62.3% of total capture (observing from otolith annual rings). The body length changed from 15.0 cm to 28.8 cm. Individuals of body length 18 cm to 21 cm were dominant occupying more than 43.3% of total capture)2. Growth of Schizothorax waltoni Regan(1) Optimum formulation between body length and body weight can be expressed w=0.0394L^2.6967(n=150,r=0.9657)(2)Relationship between body length (cm) and otolith radius: L=3.1127R^0.9012 (n=150, r=0.9710)(3) The calculation of RSS, based on annual rings reading on otolith. Vertebra opercular, scale was different. The result of RSS show that the accuracy of otolith readings are very high.?Compassion on the actual and back-calculated body weight (from body length and body weight equation). Using RSS index, RSS of data of otolith, vertebra, ppercular, Scale were respectively 1978.20, 9469.3.?Growth formula based on otolith aging, von Bertalanffy formula is extremely accurate:L, =46.5998tl-e-°1201(f+25231]Wt - 1250.67[l e-0120K'*2-5231) J2.6967 ( ? ? tfQ f R* ? 0>9803 )Decimal cubic formula is secondly accurate:L, - 0.0057*3 -0.143*2 + 2.1049* +13.023 (n -150, R2 - 0.9726)Logistic formula is not accurate :22 Sfi 4^2 39L< "----- ??,4^ ' w,----------nZ'll 2MCT > (K -0.810, n-150)o' -I -20.68-4.35r ? /-t -2O.68-4.35l\ 2.6967?Observed from VBF, Growth coefficient (k) = 0.1201 .Turning age is 11.52years.?The von Bertalanffy formula is extremely suited to model the growth of older fish (over 9 years).The Decimal cubic formula is especially suited to younger fish (under 8 years).?Condition factor is at peak in 4 age which condition factor is 1.656.Condition factor decline with age rise.?Growth index is at peak in 4 age which Growth index is 7.133. Growth index show under 4years growth is very fast, over ten years growth is declining.Growing to 100 g needs 3 years or 4 years. To 500g needs 14.1 years.?Analysis of variance for growth index of four schizothoracini from the Tibetan Plateau. The result express that notable difference exists in growth index of four schizothoracini from the Tibetan Plateau.