This paper investigates the strategic reaction of ports when they face the increasing bargaining power of shipping alliances. A dynamic game model is established to analyze the strategies of the shipping lines (competing à la Cournot or forming an alliance) and the ports (operating independently or forming horizontal cooperation or vertical cooperation). The shipping lines’ economies of scale is considered. The results in the equilibrium indicate that (1) forming the alliance is the dominant strategy for the shipping lines; (2) under the shipping alliance, the ports’ vertical cooperation reduces their charges and increases their capacities and the market outputs; (3) under the shipping alliance, when the substitutability (between the shipping lines) is strong, the ports choose horizontal cooperation; when the substitutability is weak, the ports choose vertical cooperation; and when the substitutability is intermediate, the ports choose independent operation. We also compare the social welfare and the local social welfare under the shipping alliance. The results indicate that mostly the ports’ vertical cooperation is the best for both the local social welfare and the social welfare. Moreover, our analysis is extended to the cases where the shipping lines engage in Bertrand competition, the ports can change their capacities, the ports also have the economies of scale on their operation, and the ports take asymmetric cooperation strategies, respectively. The results demonstrate the robustness of our conclusions.

本文考察了港口在面临航运联盟议价能力增强时的战略反应。建立了动态​​博弈模型来分析航运公司的战略（竞争à la古诺或结盟）和港口（独立经营或形成横向合作或纵向合作）。考虑了航运公司的规模经济。均衡结果表明：（1）形成联盟是航运公司的优势战略；（二）航运联盟下，港口纵向合作降低收费，增加运力和市场产出；（3）航运联盟下，当（航线之间）替代性强时，港口选择横向合作；当替代性较弱时，港口选择纵向合作；当可替代性为中等时，端口选择独立运行。我们还比较了航运联盟下的社会福利和当地社会福利。结果表明，大多数港口的纵向合作对当地社会福利和社会福利都是最好的。此外，我们的分析还扩展到了航运公司参与伯特兰竞争、港口可以改变其运力、港口在运营上也具有规模经济、港口采取非对称合作策略的情况。结果证明了我们结论的稳健性。