A complete census for all upstream and downstream migrating sea trout is available from the Burrishoole traps from 1971.
Wild smolt migrations in the Burrishoole system historically ranged in number from 2337 to 6710, with a significant downward trend in smolt numbers after 1990 to a minimum recorded of 769 in 2000. Smolt numbers dropped to less than 500 in 2001 indicating serious recruitment problems.