新疆乌伦古湖湖拟鲤的生长特征

Growth Characteristics of Roach Rutilus rutilus(L.) in Ulungur Lake in Xinjiang Uigur Autonomous Region

根据2007年1月至2008年5月采集的1033尾标本，以微耳石磨片为年龄鉴定和生长退算材料，对乌伦古湖湖拟鲤种群的生长特征进行了研究。结果显示：乌伦古湖湖拟鲤种群雌、雄个体均由7个年龄组（0^＋～6^＋龄）组成，相同年龄组雌鱼个体显著大于雄鱼。雌、雄鱼体重与全长表现为异速生长：W♀=0．9×10^-6TL^3.4606，W♂=1．0×10^-6TL^3.3964。用退算全长拟合的vco Bertalanffy生长参数为：雌性TL∞=300．9mm，k=0．1819／y，t0=-0．8432y；雄性TL∞=271．8mm，k=0．1974／y，t0=-0．6366y。体重生长参数为：雌性W∞=339．5g，k=0．1819／y，to=-0．8239y；雄性W∞=186．0g，k=0．1966／y，t0=-0．6450y。生长特征指数为：雌性φ=9．7089；雄性φ=9．5875。雌、雄鱼的生长拐点年龄分别为6．0龄和5．6龄，拐点时全长和体重分别为214．2mm，104．3g和192．5mm，55．5g。与20世纪90年代种群相比，乌伦古湖湖拟鲤生长速度明显下降，呈现出个体小型化和低龄化趋势。引起这种变化的主要原因可能是过度捕捞、水体盐度上升、SO4^2-和Cl^-含量升高以及种间饵料生物竞争加强。

This paper deals with the growth characteristics of roach Rutilus rutilus （L.） based on 1 033 specimens collected in Ulungur Lake from January 2007 to May 2008. The otoliths （lapilli） were used to determine the ages and back-calculate the growth of roach. The results showed that the oldest fish is 6^＋ and based on the total length, the female grow faster than the male for the same age. The body weight grew allometrically with the total length and there were significant differences in growth patterns between males and females. The total length-weight relationship can be described by the following equations.W= 1.0 × 10^-6 TL^3.3964 and W=0. 9 × 10^-6 TL^3.4606 for males and females, respectively. Growth could be described by yon Bertalanffy equation with the growth parameters： TL∞ = 271. 8 mm, k = 0. 197 4/y,t0=-0. 636 6 y for male and TL∞=300. 9 mm,k=0. 181 9/y,t0=-0. 843 2 y for female, and weight growth parameters. W∞ = 186. 0 g, k = 0. 196 6/y, to =-0. 645 0 y for male and W∞ = 339.5 g,k=0. 181 9/y,t0 =-0. 823 9 y for female. The growth performance index for male and female roach in Ulungur Lake are φ=9. 587 5 and φ=9. 708 9,respectively. The inflexion point of age for body weight and the corresponding total length and body weight is at 5. 6 years, 192. 5 mm and 55. 5 g for male,and 6.0 years,214. 2 mm and 104. 3 g for female. The growth rate of roach in Ulungur Lake had significantly declined compared with that in the 1990s. The population demonstrates a remarkable tend- ency for decrease in size and simplification in age structure. Over-fishing, increasing salinity and content of SO4^2- and Cl of water and the strengthening of inter-specific competition for food are the main rea- sons leading to the decline in growth rate and simplification in population structure of roach these changes. However, further researches are needed to find out the underlying relationship between some ecological factors and the growth rate of roach in Ulungur Lake.