Recent disruptions at major maritime chokepoints have exposed the structural fragility of liner shipping networks. Existing indicators measure connectivity, but none quantify its structural vulnerability from a supply-side perspective. We propose the Maritime Connectivity Vulnerability Index (MCVI), capturing three dimensions mapped to distinct UNCTAD sources: low overall connectivity (LSCI), weak bilateral integration (LSBCI), and port infrastructure concentration (PLSCI). The index covers 185 economies over 2006-2025 using pooled fractional rank normalization and equal-weight aggregation from publicly available data. SIDS exhibit a mean vulnerability 0.234 points above non-SIDS economies, with the gap widening from 0.232 to 0.249 over two decades. A modest global decline of 4.2% is observed. Port concentration dominates for nearly 40% of economies (72 of 185), establishing infrastructure diversification as a distinct policy priority. Rankings are highly stable across alternative weighting schemes, normalization methods (Spearman rho = 0.97-0.999), and PCA-derived weights; Monte Carlo simulation (1,000 replications) confirms rho > 0.95 in every realization. External validation shows strong negative correlation with the World Bank Logistics Performance Index (rho = -0.61 across seven waves) and positive correlation with ad valorem maritime freight rates (rho = +0.32). Panel regressions reveal a vulnerability paradox whereby small trade-dependent economies are simultaneously the most trade-open and the most vulnerable. Pre-crisis MCVI predicts trade losses during the COVID-19 supply shock (rho = -0.25, p < 0.005), while the contrasting positive correlation during the 2008-2009 demand shock (rho = +0.23, p = 0.01) validates the supply-side specificity of the index.

翻译：近期主要海上咽喉点的中断暴露了班轮运输网络的结构性脆弱性。现有指标测量连通性，但无一从供给侧角度量化其结构性脆弱性。我们提出海运连通脆弱性指数（MCVI），涵盖映射至联合国贸发会议（UNCTAD）不同数据源的三个维度：低总体连通性（LSCI）、弱双边整合（LSBCI）和港口基础设施集中度（PLSCI）。该指数基于2006-2025年185个经济体的公开数据，采用合并分数秩归一化和等权重聚合方法。小岛屿发展中国家（SIDS）的平均脆弱性比非SIDS经济体高0.234分，且在二十年间差距从0.232扩大至0.249。全球脆弱性呈微幅下降趋势（降幅4.2%）。近40%的经济体（72/185）以港口集中度为脆弱性主导因素，表明基础设施多样化已成为独立的政策优先事项。排名在替代权重方案、归一化方法（斯皮尔曼相关系数ρ=0.97-0.999）及主成分分析（PCA）推导权重下高度稳定；蒙特卡洛模拟（1,000次重复）证实每次实现中ρ>0.95。外部验证显示，该指数与世界银行物流绩效指数呈强负相关（七轮数据ρ=-0.61），与从价海运运费率呈正相关（ρ=+0.32）。面板回归揭示了脆弱性悖论：小型贸易依赖经济体同时具有最高贸易开放度和最高脆弱性。危机前的MCVI能预测COVID-19供给冲击期间的贸易损失（ρ=-0.25，p<0.005），而其在2008-2009年需求冲击期间的对比性正相关（ρ=+0.23，p=0.01）则验证了该指数的供给侧特异性。