Technological intensification and effort escalation in a small pelagic fishery: Fishing power increase along the Tanzanian coast

Small pelagic fisheries along the Tanzanian coast have undergone rapid technological upgrading over the past decade, yet its implications for fishing effort remain poorly quantified. Using VIIRS night-time light data from 2014 to 2024 combined with long-term field observations, this study examines technological intensification and effort escalation in a shared coastal dagaa fishery. Offshore radiance increased significantly over the study period (β = 0.040, p < 0.001; Mann–Kendall τ = 0.855, p < 0.001), indicating a sustained increase in fishing-related night-time light intensity. The upward trend remained significant during 2017–2024 (β = 0.032, p = 0.001), suggesting continued growth beyond the initial electrification phase. Monthly generalized least-squares analysis confirmed that the long-term increasing trend persisted despite substantial seasonal and interannual variability. Temporary fluctuations, including those observed during 2019, did not alter the overall long-term trajectory. Field observations indicate a two-phase electrification process: initial adoption of modular LED systems followed by diffusion of high-intensity LED floodlights, accompanied by increases in both the number and brightness of lights per vessel. The temporal correspondence between technological upgrading and rising radiance supports the interpretation of satellite-detected light emissions as an indicator of increasing fishing power. By integrating remotely sensed radiance data with field-based knowledge, this study provides empirical evidence of technological intensification and increasing fishing power in a data-limited small pelagic fishery. The findings highlight the importance of accounting for technological transitions when interpreting fishing effort dynamics and demonstrate the value of satellite-derived night-time lights for monitoring technological change in small-scale fisheries.