The Shieldaig trap is long term monitoring site focussed on salmonids and operating since 1999. During some years these have also operated as downstream eel traps, resulting in years with complete, partial or absent annual count data as follows: complete data 2002-2022, partial or possibly partial data 1999-2001. Small eels may evade capture by slipping through trap bars. Adult silver eels are too large to evade capture in this way, but some eels, both large and small, may bypass the traps in spates: thus annual counts represent minimum numbers. Trap protocols were similar, although not identical, over the monitoring period. Lifestage has not always been recorded, and where absent the following criteria have been applied to determine lifestage: Shieldaig, ‘silver’ if > 270 mm, otherwise ‘yellow’.