Fish population processes could exhibit non-stationary behaviour as a stochastic biological process with temporal autocorrelation that may be influenced by environmental changes. Here we developed a Bayesian autoregressive state-space surplus production modelling framework to explore potential non-stationarity in population processes. We then evaluated the consequence of non-stationary population processes on the future risk of overexploitation for three Pacific billfish stocks (striped marlin, Kajikia audax; blue marlin, Makaira nigricans; and swordfish Xiphias gladius) that are formally assessed on a regular basis by a Regional Fisheries Management Organization in the Pacific Ocean. The results showed evidence of non-stationary population processes for Western and Central North Pacific Ocean (WCNPO) striped marlin, and to a lesser extent, Pacific blue marlin and WCNPO swordfish. Trends in the theoretical maximum sustainable yield and intrinsic growth rate were observed as oscillating regimes for swordfish, and as long-term directional changes for striped marlin. The non-stationary population processes did not strongly influence the forecasted biomass trend at the current catch level for any of the three stocks. However, the future risk of overexploitation (Prob[B < B_MSY]) was sensitive to changes in the population processes for striped marlin (increased the risk by 20%). This work illustrates that the inclusion of non-stationary population processes could impose challenges for developing a stock rebuilding plan and provides a framework to account for non-stationary population processes for the billfish stocks in the Pacific Ocean.

鱼类种群过程可能表现为非平稳行为，它是具有时间自相关的随机生物过程，可能受环境变化的影响。在这里，我们开发了贝叶斯自回归状态空间剩余生产建模框架，以探索人口过程中潜在的非平稳性。然后，我们评估了非平稳种群过程对三种太平洋河豚种群（条纹马林鱼，Kajikia audax；蓝马林鱼，Makaira nigricans和剑鱼Xiphias gladius）未来过度开发风险的后果。），由太平洋区域渔业管理组织定期进行正式评估。结果表明，西北太平洋和中部太平洋（WCNPO）的条纹马林鱼以及太平洋蓝马林鱼和WCNPO旗鱼的种群数量不稳定。箭鱼的振荡方式和条纹马林鱼的长期方向变化都观察到了理论上最大可持续产量和内在增长率的趋势。对于三种种群中的任何一种，在当前捕捞水平上，非平稳种群过程都不会强烈影响预测的生物量趋势。但是，未来过度开发的风险（概率[ B  <  B _MSY]）对条纹马林鱼种群过程的变化敏感（风险增加了20％）。这项工作表明，将非平稳种群过程包括在内可能会对制定种群重建计划提出挑战，并提供一个框架来解释太平洋沿岸鱼类种群的非平稳种群过程。