Marine capture fisheries are an important source of aquatic animal protein, yet their continued dependence on fossil fuels generates substantial greenhouse gas emissions and economic burdens. Here we develop cost-optimal and carbon-neutrality pathways for China’s marine fishing vessels by combining vessel-level carbon accounting, techno-economic assessment and multi-objective optimization. We further develop the Fishing Vessel Decarbonization Technoeconomic Multi-Objective Planning Model (FVDT-MOP) to identify technology adoption pathways from 2030 to 2060 under multiple policy and market scenarios. In the base year, 70,547 vessels emitted 3.8856 × 10⁷ t CO₂ eq., with large vessels contributing 58% of total emissions and average vessel-level emissions increasing markedly with vessel size. Optimization results show that conservative and balanced pathways are dominated by electrification, biodiesel, and vessel retirement, achieving cumulative reductions of 5.195 × 10⁸ and 5.485 × 10⁸ t CO₂ eq. at costs of 75.614 and 91.903 billion yuan, respectively. Aggressive mitigation further increases cumulative reductions to 5.974 × 10⁸ t CO₂ eq. but with sharply higher marginal abatement costs. These findings highlights that fisheries decarbonization requires not only technological substitution, but also adaptive management strategies that balance emission reduction, economic feasibility, and fleet restricting. By identifying differentiated pathways across vessel types and mitigation ambition levels, this study provides practical evidence for designing targeted subsidies, phased technology adoption, and carbon-neutrality pathways for fisheries sector. The results contribute to broader efforts to build resilient, low-carbon and sustainable ocean systems.