Supplement 4: Code for Theoretical Model from Biodiversity underpins fisheries resilience to exploitation in the Amazon river basin

Inland fisheries feed greater than 150 million people globally, yet their status is rarely assessed due to their socio-ecological complexity and pervasive lack of data. Here, we leverage an unprecedented landings time series from the Amazon, Earth's largest river basin, together with theoretical food web models to examine (i) taxonomic and trait-based signatures of exploitation in inland fish landings and (ii) implications of changing biodiversity for fisheries resilience. In both landings time series and theory, we find that multi-species exploitation of diverse inland fisheries results in a hump-shaped landings evenness curve. Along this trajectory, abundant and large species are sequentially replaced with faster growing and smaller species. Further theoretical analysis indicates that harvests can be maintained for a period of time but that continued biodiversity depletion reduces the pool of compensating species and consequently diminishes fisheries resilience. Critically, higher fisheries biodiversity can delay fishery collapse. Although existing landings data provide an incomplete snapshot of long-term dynamics, our results suggest that multi-species exploitation is affecting freshwater biodiversity and eroding fisheries resilience in the Amazon. More broadly, we conclude that trends in landings evenness could characterize multi-species fisheries development and aid in assessing their sustainability.

全球内陆渔业为超过1.5亿人口提供生计支撑，但由于其社会生态复杂性及普遍存在的数据匮乏问题，其资源现状罕有被系统评估。本研究依托来自全球最大河流流域——亚马孙流域的前所未有的渔获时间序列数据，并结合理论食物网模型，开展两项核心分析：（1）内陆渔业渔获中捕捞开发的分类学与功能性状特征信号；（2）生物多样性变化对渔业恢复力的影响机制。无论是基于实际渔获时间序列还是理论模型，我们均发现：对多样化内陆渔业开展的多物种捕捞开发，会呈现出驼峰型的渔获均匀度曲线。沿该变化轨迹，体型硕大、种群丰富的物种会依次被生长速率更快、体型更小的物种所取代。进一步的理论分析表明，渔获产量可在短期内维持，但持续的生物多样性耗竭会削减可发挥补偿作用的物种种群库，进而削弱渔业恢复力。尤为关键的是，更高的渔业生物多样性可延缓渔业种群崩溃。尽管现有渔获数据仅能呈现长期动态的不完整快照，但本研究结果显示，多物种捕捞开发正在对亚马孙流域的淡水生物多样性造成影响，并逐步侵蚀其渔业恢复力。从更广泛的视角来看，本研究得出结论：渔获均匀度的变化趋势可用于表征多物种渔业的发展状态，并有助于评估其可持续性。