Marine heatwaves (MHWs) are extreme climatic events that profoundly affect marine ecosystems and fisheries. The duration of MHWs is a key factor governing the severity of ecological effects, yet the contrasts of characteristics, drivers, and possible influences on fisheries between short- lived MHWs (≤30 days) and long-lived MHWs (> 30 days) remain poorly understood. By examining MHWs of varying durations in the tropical western Pacific Ocean, we revealed that short-lived MHWs are driven by surface heat fluxes and have nearly symmetric life cycles (i.e., comparable rates of onset and decay), whereas long-lived MHWs exhibit a slow onset and multiple peaks and are sustained by ocean dynamics, such as oceanic advection and anomalous upwelling. By integrating fishery catch records, we found that the catch of small pelagic and reef-associated fish declined during long-lived MHWs compared to short-lived MHWs. These findings provide a deeper understanding of MHWs and a foundation for adaptive management strategies that safeguard the blue economy.