Heterogeneity in carbon emission efficiency across global marine capture fisheries: a metafrontier analysis of technology gaps and reduction potentials

Improving the carbon emission efficiency of marine capture fisheries is important for the sustainable development of fisheries under climate change. Using 66 major marine fishing countries over 1995–2017 as the sample, we divided the countries into three groups by fishing structure: high-input predatory fish-dominated, mixed, and small pelagic and other finfish-dominated. We measured carbon emission efficiency with a slacks-based measure (SBM) model with undesirable outputs and a metafrontier approach, and decomposed the potential emission reduction into managerial inefficiency and the technology gap. The results show the following. (1) Carbon emission efficiency was generally low, with a mean metafrontier efficiency of 0.331, and the differences between groups were closely related to catch value. (2) The technology gap was concentrated in the high-input predatory fish-dominated group and the small pelagic and other finfish-dominated group, and its causes differed across countries: in Vietnam, Thailand and Malaysia it was associated with fuel-intensive fishing operations, whereas in Peru and Chile it stemmed from the low value of the catch. (3) The mean annual potential carbon emission reduction of the sample countries was 85.4 Mt CO 2 -eq, about 53% of their total emissions, and was concentrated in countries such as Indonesia, India and Vietnam. (4) Managerial inefficiency was the main source of the reduction potential, accounting for 69%. In the mixed group, almost all of the potential came from managerial inefficiency; in the high-input predatory fish-dominated group, the technology gap dominated; and in the small pelagic and other finfish-dominated group, both sources contributed. Countries should therefore choose different pathways according to the source of their reduction potential. For most countries, catching up with the best practice of similar countries could release most of the potential with existing technology, especially in countries where the potential is concentrated, such as Indonesia and India. Countries whose technology gap is accompanied by high fuel intensity should focus on promoting energy-saving fishing gear and propulsion technology, while countries that mainly land low-value catch should increase the value of their catch.