Table_1_An integrated catch-at-age model for analyzing the variability in biomass of Pacific sardine (Sardinops sagax) from the Gulf of California, Mexico.docx

Knowledge of the population dynamics and changes in the abundance of Pacific sardine fishery is relevant for fishery management. In this study, an integrated catch-at-age model (ASAP) was performed on 47 fishing seasons (1971−2018) of Sardinops sagax in the Gulf of California, including five indices of relative abundance (survey catch rate, acoustic surveys, egg and larvae, spawning probability, and bird diet index). The ASAP model showed the importance of age group 0 (recruits); this is the most important age group in the Pacific sardine fishery, and its abundance has consequences for the variability of the total abundance of the species. In this study, the spawning and acoustic indices denoted the changes in abundance of Pacific sardine population better than the survey catch rate and bird diet ratio. Historically, the total biomass is estimated to have varied from 461 thousand to 4.82 million t. In the 1970s and 1980s, a peak biomass close to three million tons was reached, and in the second peak from the mid-1990s to the late 2000s, the total biomass varied between 3.26 and 4.82 million t. When the spawning biomass was at least 750 x 103 t, the recruitment (age group 0) showed high values, promoting high catches in the subsequent years. The annual fishing mortality estimates did not show a rise related to the periods of high harvestable biomass; therefore, the catch records were low in comparison to the harvestable biomass estimated from ASAP, and the annual fishing mortalities were less than 0.22 during periods of high abundance. The changes in biomass and the variability observed in the Pacific sardine fishery were validated for the model diagnostics; the retrospective patterns did not identify poor fits to data, therefore the robustness of the model can be used for management purposes. According to the Kobe phase plot, the Pacific sardine fishery in the Gulf of California has been fully exploited with an apparent stable level of harvest.

明晰太平洋沙丁鱼渔业的种群动态与资源量变化规律，对渔业管理工作具有重要指导意义。本研究针对加利福尼亚湾1971−2018年共47个渔季的沙丁鱼（Sardinops sagax）种群，采用综合年龄结构捕捞模型（integrated catch-at-age model, ASAP）开展分析，纳入5项相对资源量指数：调查捕捞率、声学调查数据、鱼卵与仔鱼数据、产卵概率指数以及鸟类食性指数。
ASAP模型结果显示，0龄组（recruits，补充群体）具有核心地位：其作为太平洋沙丁鱼渔业中最为关键的年龄组，资源量波动将直接影响该物种种群总资源量的变化幅度。
本研究中，产卵指数与声学指数相较调查捕捞率及鸟类食性比率，能更精准地反映太平洋沙丁鱼种群的资源量变化。
历史数据显示，该种群总生物量的估算值介于46.1万吨至482万吨之间。
20世纪70至80年代，其生物量达到近300万吨的峰值；1990年代中期至2000年代末的第二次峰值期间，总生物量波动于326万吨至482万吨区间。
当产卵生物量不低于75万吨（750×10³ t）时，0龄补充群体的资源量将处于高位，进而推动后续年份的捕捞产量提升。
年度捕捞死亡率的估算结果未出现与可开发生物量高企时期相关的上升趋势，因此相较ASAP模型估算的可开发生物量，实际捕捞记录偏低；在种群资源量充沛的时期，年度捕捞死亡率均低于0.22。
本研究通过模型诊断对太平洋沙丁鱼渔业的生物量变化及资源波动进行了验证，回溯检验模式未发现模型对数据存在拟合不佳的情况，因此该模型具备足够稳健性，可应用于渔业管理工作。
根据科比相图（Kobe phase plot），加利福尼亚湾的太平洋沙丁鱼渔业目前已处于充分开发状态，捕捞水平整体保持稳定。