底拖网调查数据的Delta-模型分析及其在黄海小黄鱼和银鲳资源评估中的应用

Bottom trawl survey data analysis based on Delta-distribution model and its application in the estimation of small yellow croak and silver pomfret in Yellow Sea

底拖网调查(扫海面积法)的数据处理方法主要有两大类,即基于调查设计的方法(design-based method)和基于模型的方法(model-based method),其中基于调查设计的方法在我国的应用较为常见,而基于模型的方法则较少应用。介绍了渔业资源底拖网调查数据的Δ-分布模型分析方法,并采用此方法对2000年秋季黄海小黄鱼和银鲳的资源量进行了评估。结果显示,调查海区小黄鱼资源的平均分布密度为66.3kg.km-2,95%置信区间为(23.4,109.2)kg.km-2;总资源量均值为14 626.9t,95%置信区间为(5 168.4,24 085.5)t。银鲳资源密度均值为19.0kg.km-2,95%置信区间为(3.5,34.5)kg.km-2;总资源量均值为4 194.3t,95%置信区间为(773.2,7 615.4)t。传统的基于调查设计的方法得到的置信区间范围则较宽,且下限出现负值。上述结果表明Δ-分布模型法的评估结果具有较高的精度,是一种值得推广的渔业资源底拖网调查数据分析与资源评估方法。

There are two groups of methods, namely, the design-based methods and the model-based methods that are commonly used for the analysis of bottom trawl survey data based on swept area method. While the design-based methods enjoy wide application, the model-based methods are seldom used in China. The Delta- distribution model-based method is described and then applied for the estimation of small yellow croaker and silver pomfret in the Yellow Sea based on a survey conducted in autumn, 2000. It shows that the stock density of small yellow croaker was 66.3 kg·km^-2 and its 95 % Confidence Interval （CI） was （23.4,109.2） kg·km^-2; the total biomass of small yellow croaker in the survey area was 14 626.9 t and its 95% CI was（5 168.4,24 085.5） t. Stock density of silver pomfret was 19.0 kg.km-2 and its 95% CI was（3.5,34.5） kg·km^-2, the total biomass of silver pomfret in the survey area was 4 194.3 t and its 95% CI was（773.2, 7 615.4） t. The traditional design-based method, however, resulted in much wider confidence intervals with negative low limits. The above results indicate that the Delta-distribution model-based method may provide estimates with higher precision, and deserve a much wider application in data analysis for the stock assessment using bottom trawl surveys.