Purpose -- The study assesses the significance of environmental uncertainty and its effects on fishing strategies of small-scale fishermen in Ende, Flores, Indonesia. Periodic environmental cycles such as the moon phase can have important effects on fishing strategies by regulating the behavior of stocks and tides. Traditional lunar calendars are used by subsistence fishermen to decide when and where to go fishing. Environmental uncertainty, specifically unprecedented changes in oceanographic and atmospheric conditions, is threatening the predictability of traditional systems of ecological knowledge. Methodology/approach -- Methods included ethnographic and observational techniques. Interviews (n = 58) and surveys (n = 132) are qualitatively and quantitatively analyzed. A combination of standard statistical tests, multilevel models, and cluster analysis is applied to long-term repeated observations of fishing events (n = 2,633). Findings -- Endenese fishermen emphasized the importance of the traditional lunar calendar to allocate their effort in interviews and surveys. This belief does not coincide with observed behavior. Contrary to expectations from the traditional calendar, the lowest probability of fishing happens in the intermediate phases, with fishing also occurring during the full moon. Differences between individuals play an important role in explaining variability in returns. Finally, based on the consideration of variability, three different fishing strategies are identified that suggest an effect of environmental uncertainty in effort regulation. Research implications -- The paper underlines the importance of studies of variability to identify behavioral flexibility and adaptation. Results emphasize the value of considering individual traits in the analysis of subsistence practices. [ABSTRACT FROM AUTHOR]