基于渔港抽样调查不同捕捞方式CPUE单位标准化新方法

本研究是在阐明传统CPUE(Catch Per Unit Effort)单位表述多样性的基础上,分析传统CPUE存在的不确定性、单位不统一性以及解析与意义不完整等问题。对24个CPUE单位,首先通过通用性标准,筛选出各种捕捞方式均能适用的8个CPUE单位;再通过相似性标准,对CPUE单位聚类分成2组,并在每组中筛选出最佳单位为kg/(kW·d)和kg/d;最后通过稳定性筛选标准对其标准差与变异系数值计算,最终得到CPUE的标准单位:kg/(kW·d),并确定CPUE的表达形式。本研究还基于CPUE单位标准化进行了实证分析,对2016年4个季度南海三省区的9种主要作业类型渔船的生产调查数据进行了分析比较,捕捞能力大小依次为:围网双拖刺网罩网张网单拖拖虾笼壶钓具。CPUE经单位标准化后已具备进行捕捞产量统计、评估渔船捕捞能力、衡量资源相对丰度指数、评估渔业资源利用水平等功能。

A Novel Approach to Unit Standardization of CPUE for Multiple Types of Fishing Gear Based on Fishing Port Sampling Surveys

Traditional CPUE (catch-per-unit-effort) units show diversity and complexity due to the different types of fishing methods, sizes of vessels, and characteristics of fisheries on which they are based, leading to problems with data incomparability among multiple fishing gear types. To assess the fish stocks in a specific areas of the sea, the impact of various different fishing types needs to be considered, but using traditional CPUE data makes it difficult to assess these stocks because of variations in the units used. We reviewed the relevant literature and screened out 24 types of CPUE units. The following processes were then carried out to standardize CPUE units across multiple fishing types. First, eight CPUE units appropriate for different fisheries were selected based on general criteria. Those CPUE units were then divided into two groups based on overall similarities and differences. The two main applicable CPUE units of kg/(kW·d) and kg/d were identified at this stage. Finally, the coefficient of variation (CV) of each of these two selected CPUE units was calculated. The smaller the value of the CV was, the more stabile the unit was concluded to be. The optimum unit was determined to be kg/(kW·d) based on this stability criterion. The landings of nine major fishing types in the South China Sea in each of the four seasons of 2016 were then analyzed using this optimal CPUE unit. The results of this analysis showed that the fishing capacity of different gear types were arranged in the following order: Seine > Pair trawl > gillnet > falling-net > stow net > otter trawl > shrimp trawl > pot > fishing tackle, corresponding to mean values of 29.57, 8.77, 4.96, 4.81, 4.73, 3.95, 3.11, 3.08, and 2.35 kg/(kW·d), respectively. After catch data are standardized by the optimal novel CPUE unit developed in this study, comparisons and analyses of fishing capacity among gear types, relative abundance and utilization levels of different fisheries resources, and fisheries catch statistics could be conducted with greater accuracy than was previously possible.