The twaite shad (Alosa fallax) has declined across much of its European range due to habitat degradation, pollution and river fragmentation . Following improvements in water quality, the species has recently re-established in the Scheldt estuary after nearly a century of absence. However, the demographic characteristics of this recovering population remain unknown. This study aimed to characterize the age structure, growth, maturation and spawning frequency of twaite shad in the Scheldt estuary using scale analysis. Individuals ranged from 3 to 9 years of age, with ages 5 and 6 dominating the population. Females attained larger sizes and were the oldest individuals, while males matured earlier. Growth was rapid during the first two years and slowed progressively with age, with the Gompertz model providing the best fit for the length-at age data. Annual spawning was the dominant reproductive strategy and skipped spawning was rare. This study established a demographic baseline for the recovering twaite shad population in the Scheldt estuary. The observed demographic characteristics are consistent with a population recovering from historically low abundance, particularly the rapid growth and large size-at-age. These findings provide essential reference information for future monitoring and conservation of this protected species.
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