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铜鱼是典型的半洄游性鱼类,曾是长江干流的重要渔获对象,但目前其资源已严重衰退。为了解三峡工程蓄水后、金沙江一期工程蓄水前该物种的种群动态,论文利用2007—2009年长江上游江津江段的渔业调查数据,采用体长频率法对其种群参数和资源量进行评估。结果表明:铜鱼渔获群体体长范围为125~530 mm,体重范围为24~2 250 g,平均体长为228.7±56.6 mm,平均体重为206.4±251.9 g;优势体长组为150~270 mm,约占总数的80.4%。铜鱼体长-体重幂函数关系为:W=7.63×10~(-6)L~(3.10)(R~2=0.97,P<0.01,n=280)。由体长频率法拟合出其渐近体长L∞为630.0 mm,生长系数k为0.23 a~(-1)。由Pauly经验公式估算出其自然死亡系数为0.46。由长度转渔获物曲线估算出其总死亡系数为1.82。江津江段铜鱼开捕体长为170.7 mm,资源开发率为0.75,超过了其资源最大开发率(0.50)。由体长结构实际种群分析估算出江津江段铜鱼2007、2008和2009年年资源量分别为2 820尾/km(2.63 t/km)、3 035尾/km(4.71 t/km)和8 130尾/km(16.56 t/km),平均值为4 661尾/km(7.96 t/km)。在当前铜鱼资源急剧下降,长江中、下游资源近乎枯竭的现状下,建议停止对铜鱼资源开发,重点加强长江上游江津江段铜鱼种群保护及其生境修复。
Copperfish is a typical semi-migratory fish, once the main catch of the Yangtze River, but its resources have been a serious recession. In order to understand the population dynamics of the species before the impoundment of the Three Gorges Project in the first phase of Jinsha River project, this paper uses the body length and frequency method to study the population parameters and resources of the species in the Jiangjin section of the upper reaches of the Yangtze River from 2007 to 2009 to evaluate. The results showed that the length of the catch population of copperfish was 125-530 mm, the weight range was 24-2 250 g, the average body length was 228.7 ± 56.6 mm, the average body weight was 206.4 ± 251.9 g, 270 mm, accounting for 80.4% of the total. The relationship between body length and body weight power function was: W = 7.63 × 10 -6 (3.10) (R ~ 2 = 0.97, P <0.01, n = 280). The asymptotic body length L∞ was fitted by body length frequency method to 630.0 mm, and the growth coefficient k was 0.23 a ~ (-1). The natural death rate was estimated by Pauly’s empirical formula to be 0.46. The total mortality was estimated to be 1.82 from the length-to-catch curve. The length of the copper fish caught in Jiangjin section was 170.7 mm and its resource development rate was 0.75, exceeding the maximum development rate of its resources (0.50). According to the actual population analysis of body length structure, the annual resources of copper fish in Jiangjin section were estimated to be 2 820 / km (2.63 t / km), 3 055 / km (4.71 t / km) and 8 130 tails / km (16.56 t / km), an average of 4 661 tails / km (7.96 t / km). Under the current situation that the resources of copper fish drop rapidly and the resources in the middle and lower reaches of the Yangtze River are almost depleted, it is suggested to stop the exploitation of the resources of copper fish and to strengthen the protection and restoration of the population of copper fish in the Jiangjin section of the upper reaches of the Yangtze River.