Because most food processes are fossil fuel–based, many food markets are more or less connected to the oil market. Fishing technology in the high seas being energy-intensive, higher oil prices should affect the fish markets. This research looks at price transmission between marine diesel oil and a global fishery commodity, frozen skipjack tuna (Katsuwonus pelamis) through a time series analysis combining four different methods to look for possible structural breaks and regime shifts in the relationship (Bai-Perron, Lavielle, Gregory-Hansen, Markov-switching). Our results prove that the long-run equilibrium between both prices is weakening after the turn of the 2010s. Explaining the drivers of change is of great interest for short-term forecast but also to build long-term scenarios where both supply and demand variables are likely to affect tuna markets.