双凤水库银鲫(方正银鲫)的年龄与生长研究

A STUDY ON AGE AND GROWTH OF CRUCIAN CARP IN SHUANGFENG reservoir

本文报道了双凤水库银鲫的年龄生长特征。以银鲫鳞片上的年轮作为年龄鉴定依据。渔获物中2龄和3龄的个体占80％以上,体长以120～150nm为主。体长与鳞长之间呈直线正相关BL=21.20+28.91R,体重与体长呈指数函数相着(?)♀=9.252×10^(-5)BL^(2814),(?)♂=1.685×10^(-5)BL^(3,155)。2龄以前生长较快,以后转入缓慢,生长适合Von Pertalanffy方程:1t=192.4〔1-e^(-kt(?)0.093)〕,体重生长曲线的拐点位于2.06龄的(?)=0.296(?)处♂与1975年资料相比,现在的生长速度明显缓慢,作者认为主要由于群体更替所致。

384 specimens were collected for making a study of Crucian carp in Shuangfeng reserv oir during 1987-1989. The results were summarized as below:1. The annual ring of the scales between dorsal fin and lateral line is the clearest. The scale radius is the longest. The coefficient of variance for the scale radius is the smallest. The correlation between body length and scale length is more intimate. Therefore, the scales arc the best specimens for determining the age of Crucian carp.2. The correlation between the body length and scale length is linear, and the formula is B.L = 21.20 + 28.91 R r= 0.89-1.3. Two years and three years old Crucian carp are more than 80% in fish catch of Shuangfeng reservoir and most individual body length is 120-150mm.4. The exponential function is the correlation between body weight andbody length. The correlation formula is: B.W = 9.252 ×10-5B.L2814B.W = 1.683 ×10-5B.L3.1555. The von Bertalanffy equation expressed a general rule of the growth of Crucian carp in Shuangfeng reservoir Based on the datum presented in this paper, the parameters can be obtained as follows:Lt=192.4[1-e-0.511(t+0.093)]L∞= 192.4mm, W∞ = 252.4g. t0 = 0.093-K = 0.511. Crucian carp grows faster before two years old, slower after two years old. The critical position of body weight growth curve is location 2.06 years old point W(W = 0.297W∞). Compared with the parameters in 1975 (L∞ = 149.9mm, W = 2704.6g t0 = 0.48. K = 0.25) . the Crucian carp current growth has been evidently slowed.6. Both the morphological features and growth have been changed with Crucian carp. The main reason is that after fast growth original population gradually deodened, the new population, artificial released and immigrated from river have substituted for original population.