In the context of climate change, which accentuates the growing scarcity of fishery resources, young fishermen are exploring increasingly remote fishing grounds with the immediate consequence of numerous cases of accidents and disappearances at sea and many human and material losses. Faced with this situation of looking for solutions to prevent accidents, the traditional knowledge of West African fishermen was examined. Semi-structured interviews and focus group meetings with fishermen aged 50 years or older were used to explore ways of understanding and predicting changes in the marine environment. It shows that experienced fishermen can apprehend the sea state, the occurrence of wind or precipitation, or orient themselves and understand the nature of fishing grounds and species through the stars, swell, waves, water table, animals, trees, clouds, sky colour, dugout, fish. The understanding, interpretation and, subsequently, the meaning they develop from their observations are based on empirical knowledge that can be tested and confirmed in other parts of the world. In this sense, the ways in which fishermen understand changes in the marine environment can be considered universal knowledge. Such knowledge, when properly transcribed, can be useful for conventional marine research and the prevention of accidents at sea, especially for the new generation of fishermen who rely solely on new technologies.