长江上游江津江段铜鱼种群参数和资源量评估

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^-6L^3.10（R²=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。

Estimating Population Parameters and Abundance of Coreius heterodon in Jiangjin Section of the Upper Yangtze River

Coreius heterodon, a representative semi-migratory species, is one of the important economic fish species in the main channel of the Yangtze River. However, its resources has been in serious degradation. To understand its population dynamics after the Three Gorges Reservoir and before the Xiangjiaba and Xiluodu reservoirs were impounded, we used FAO-ICLARM Stock Assessment Tools based on length-frequency data to estimate the growth and mortality parameters, and population abundance of C. heterodon based on surveys in Jiangjin section conducted in 2007-2009. The fishes ranged from 125 to 530 mm in length and 24 to 2 250 g in weight, with an average length of 228.7 ± 56.6 mm and an average weight of 206.4 ± 251.9 g. The length group of 150-270 mm dominated the catches (80.4% of the total number). The length-weight relationship of C. heterodon fit well with a power function, W = 7.63×10^-6 L^3.10 (R² = 0.97, P < 0.01, n = 280). Asymptotic length (L_∞) and growth constant (k) were estimated using length frequency data to be 630.0 mm and 0.23 a^-1, respectively. Natural mortality was estimated to be 0.46 using the empirical formula proposed by Pauly. The total mortality was estimated using a length-converted catch curve analysis to be 1.82. The minimum catchable size was 170.7 mm, and the exploitation rate observed was 0.75, which was higher than the estimated maximum exploitation rate (0.50). Population abundance of C. heterodon in Jiangjin section was estimated by length-structured virtual population analyses to be 2 820 ind·km^-1 (2.63 t·km^-1) in 2007, 3 035 ind· km^-1 (4.71 t· km^-1) in 2008, and 8 130 ind·km^-1 (16.56 t· km^-1) in 2009, respectively, with an study average of 4 661 ind· km^-1 (7.96 t· km^-1). In view of the rapidly declined resources of C. heterodon in the Yangtze River, especially in the lower reaches, we suggest to stop exploiting the resources immediately. We also suggest Jiangjin section should be considered as the prior region for population conservation and habitat restoration of C. heterodon.