Abstract:Fishery resource surveys are an important basis for the scientific management and conservation of fishery resources. The representativeness of resource survey stations is particularly important because there is limited sampling time and space. Optimizing the design of fishery resource survey stations under limited conditions is always the focus of fishery resources research. Taking the Bohai Sea as a study area and using a numerical simulation method, this paper analyzed the impact of species occurrence rate (17 main species were divided into three categories: classⅠwith an occurrence rate of more than or equal to 70%, class Ⅱ with an occurrence rate of 50%~70%, and class Ⅲ with an occurrence rate of lower than 50%) and habitat water layer on the relative error (REE) of single species biomasses, explored the influence of the number of stations (48 and 60) on the results of stationary sampling and stratified random sampling, and further optimized the design of multi-objective fishery resource surveys in the Bohai Sea. Results showed that the relative errors of biomass for five species in class Ⅰ, three species in class Ⅱ, and six species in class Ⅲ were less than 20%, less than 30%, and less than 35%, respectively. This indicated that the relative error for single species biomasses increased with a decline in the species occurrence rate, while the habitat water layer had no significant influence on the REE of species biomasses. As the number of survey station decreased, the accuracy value for stationary sampling decreased (the REE of biomass indexes for fish, shrimp, crab, and cephalopod increased by 1.1%, 2.5%, 8.4%, and 4.4%, respectively, and the REE of Margalef richness index increased by 3.3%). Stratified random sampling could compensate for the declining accuracy due to a decrease in the number of survey stations. For example, the accuracy of the fish biomass index (REE is 4.6%) obtained by stratified random sampling with 48 survey stations is higher than that obtained by stationary sampling with 60 survey stations (REE is 7.7%), which could help reduce survey costs and protect low-abundance species. However, each sampling method could not fully satisfy the multi-objective optimization, and the accuracy of stratified random sampling was affected by station allocation schemes. Setting survey stations based on the optimal criterion of sampling cost can obtain a higher accuracy of biomass assessment for fish, shrimp, crab, cephalopod, and main species such as Setipinna taty, Oratosquilla oratoria, Loligo japonica, Engraulis japonicus, Johnius grypotus, Carcinoplax vestita, and Fenneropenaeus chinensis, and could be used as a station design scheme for multi-objective fishery resource surveys in the Bohai Sea.
