应用Catch-MSY模型评估印度洋蓝枪鱼资源

Stock assessment for Indian Ocean blue marlin(Makaira nigricans) using Catch-MSY model

Catch-MSY模型可仅依靠渔获量数据进行渔业资源评估,在数据缺乏状况下能暂时替代标准资源评估模型。本研究以印度洋蓝枪鱼(Makaira nigricans)为例,根据有、无信息的内禀增长率r和环境容纳量K的先验分布,设立15组情景进行模型灵敏度分析、资源评估和预测。结果表明,参数r和K呈强烈的负相关,而最大可持续产量(Maximum Sustainable Yield,MSY)与参数r呈正相关;数据时间序列长度对评估结果影响有限,而模型对起止年渔获量较为敏感。资源状况评估表明,印度洋蓝枪鱼资源生物量状况良好,即B2015/BMSY大于1;而开发状况除其中两种情景外,均为过度捕捞,即F2015/FMSY大于1。资源预测表明,为使未来10年内B/BMSY>1的概率超过50%,需将渔获量缩减至当前渔获量的90%(13.86kt);考虑到该模型在数据缺乏状况下会更加保守,若将当前渔获量的100%~110%(15.40~16.94kt)设为管理目标,则未来5年内B/BMSY>1的概率超过50%。

Catch-MSY method can temporarily replace conventional stock assessment models in making management decisions for a data-limited fishery, even when only catch data are available. In this study, for the sensitivity analysis and assessment of the Indian Ocean blue marlin, we established 15 scenarios based on non-informative and informative prior distributions of the intrinsic growth rate r and carrying capacity K. Sensitivity analysis reveals a high negative correlation between parameters r and K, and the estimated maximum sustainable yield (MSY) increases with r. Sensitivity analysis shows that the length of catch time series has less influences on the results of the assessments, but the assessments are sensitive to catch data in the first and last year. The assessment results reveal that the status of total biomass is optimal, with the ratio of B2015 to BMSY higher than 1. Exception is only two scenarios, the exploitation status under the other scenarios would be overfishing, since all the ratios of F2015 to FMSY would be higher than 1. Projections of future stock status show that, to attain the objective of maintaining B/BMSY>1 with a probability of higher than 50% in the next 10 a, the catch would have to be reduced to 90%(13 860 t) of the current level. Considering that the catch-MSY method is conservative under data-limited conditions, maintaining 100% to 110%(15 400–16 940 t) of the current catch could achieve the objective of maintaining B/BMSY >1 with a probability of higher than 50% in the next 5 a.