新疆乌伦古湖拟鲤生长退算材料和方法的比较研究

COMPARISON OF FOUR METHODS USING SCALES AND LAPILLI FOR BACK-CALCULATION OF ROACH RUTILUS RUTILUS (LINNAEUS, 1758) IN ULUNGUR LAKE, XINJIANG UIGUR AUTONOMOUS REGION, CHINA

研究以鳞片和微耳石为生长退算材料,用4种常用的鱼类生长退算方法(Dahl-Lea、Regression、Fraser-Lee和BPH方法)对新疆乌伦古湖拟鲤(Rutilus rutilus Linnaeus,1758)的生长进行了退算,比较分析了退算材料和方法对退算全长的影响,以此确定适宜的生长退算材料和方法。结果显示,无论采用哪种退算方法,用微耳石退算拟鲤生长的结果均好于鳞片,表现为退算全长更接近实测全长,与实测体长之间的差异百分比更小。用鳞片退算时,Dahl-Lea方法退算全长远小于实测全长,整体差异百分比高达-26.0%,与其他方法之间的差异也较大,效果最差;Regression、Fraser-Lee和BPH三种方法退算全长与实测全长之间的差异相近,差异百分比分别为-6.7%、7.0%和7.0%。用微耳石退算时,Dahl-Lea方法退算全长最接近实测全长,退算全长与实测全长之间的差异百分比最小,总体仅为-1.9%,效果最好;Fraser-Lee和BPH方法各龄退算全长与实测全长之间的差异百分比相等,在-1.4%-?3.2%之间,总体均为-2.6%,效果次之;Regression方法与Fraser-Lee和BPH方法之间虽然无显著差异,但退算全长与实测全长之间的差异百分比最大,总体为-4.5%,效果最差。

Back-calculation, which uses a set of measurements from the bony structures in the age determination and its current body length at one time to infer its length at an earlier time or times, is a very important tool in fisheries research and management. Because a lot of bony structures can be used in age determination, and the relationship between the chosen structure and the body length of fish also can be described with various linear or non-linear equations, several back-calculation models have been proposed. In order to expand confidence in estimation of growth parameters of a particular fish species, it is necessary to obtain a comparison of back-calculated lengths from different structures and models. The present study dealt with the suitable calcified tissues and methods used for growth back-calculation of roach Rutilus rutilus （Linnaeus, 1758） from Ulungur Lake, the second largest lake of Xinjiang Uigur Autonomous Region, one of the tenth freshwater lakes in China. Two calcified tissues （scales and lapilli） and four common back-calculation methods （Dahl-Lea, Regression, Fraser-Lee and BPH） were utilized for growth back-calculation. The reliability was evaluated by comparing the back-calculated lengths at ages with observed lengths at the annuli formation. It was shown that the back-calculated lengths obtained by the lapilli were more reliable than those obtained by scales, with smaller differences from observed lengths. So, it was demonstrated that the lapilli were the better material both for age deter-mination and back-calculation of roach. For scales, the Dahl-Lea method provided the most unreliable estimates of fish lengths at previous ages, with the largest differences from the observed length （-26.0%）, it also had significant differ-ences from the other three methods. The differences between the back-calculated lengths from the Regression, Fra-ser-Lee and BPH method and the observed lengths were very close, which was -6.7%, -7.0% and -7.0% respectively. It indicated that the three methods were equal for the back-calculation of roach. For lapilli, the Dahl-Lea was the best method for the back-calculation of roach with the smallest （-1.9%） difference from the observed lengths. The Regres-sion method was the worst one with the largest difference from the observed lengths （-4.5%）. The Fraser-Lee method provided the similar results with the BPH method and the differences from the observed lengths were both between -1.4% and -3.2%, averaged -2.6%. They were secondary for growth back-calculation of roach.