Assessing the Adaptation between Recreational Fisheries Development and Aquaculture Efficiency in Multifunctional Freshwater Fisheries Systems: Evidence from China

To examine the synergy quality and potential mismatch risks between production and recreational functions during the multifunctional transformation of freshwater fisheries, this study constructs a composite index of recreational fisheries development using panel data from 29 Chinese provinces during 2008–2023. Freshwater aquaculture efficiency is measured using a benevolent cross-efficiency model incorporating both desirable and undesirable outputs. An integrated adaptation model is then employed to capture the spatiotemporal differentiation of the adaptation relationship between the two systems, while Random Forest and SHAP methods are applied to identify nonlinear effects and threshold characteristics of key drivers. The results indicate that: (1) both recreational fisheries development and aquaculture efficiency increased steadily over the study period, whereas the composite adaptation index remained at low-to-medium levels with limited stage-wise improvement, suggesting that efficiency gains have not been effectively translated into recreational advantages; (2) the adaptation pattern exhibits pronounced regional differentiation and path dependence, characterized by persistently higher levels in central China, gradual improvement in eastern China, increasing polarization in western China, and consistently low and weakening adaptation in northeastern China; and (3) the driving mechanisms are markedly nonlinear, with water environmental pressure and tourism reception intensity acting as key constraints. Specifically, water quality pressure shows an inverted U-shaped effect with clear thresholds, while tourism intensity exerts a sustained inhibitory impact. This study provides empirical evidence for incorporating adaptation relationships into fisheries transformation assessments and for region-specific optimization of industrial structure and spatial allocation.