RT Journal Article SR Electronic T1 The Low Abundance and High Catchability of Large Piscivorous Ferox Trout (Salmo trutta) in Loch Rannoch, Scotland JF bioRxiv FD Cold Spring Harbor Laboratory SP 029801 DO 10.1101/029801 A1 Alastair Thorne A1 Alasdair I. MacDonald A1 Joseph L. Thorley YR 2015 UL http://biorxiv.org/content/early/2015/10/23/029801.abstract AB The Ferox Trout is an ancient member of the Brown Trout (Salmo trutta) species complex that may constitute its own species: Salmo ferox. Due to their exceptionally large size, Ferox Trout are highly sought after by anglers while their life-history strategy, which includes delayed maturation, multiphasic growth and extended longevity, is of interest to ecological and evolutionary modelers. However, despite their genetic, recreational and theoretical importance, little is known about the typical abundance of Ferox Trout or their vulnerability to angling. To rectify this situation a 16 year mark-recapture study was conducted on Loch Rannoch, which at 19 km2 is one of the largest lakes in the United Kingdom. A hierarchical Bayesian Jolly-Seber analysis of the data indicates that in 2009 the population of Ferox Trout in Loch Rannoch was approximately 71 individuals. The results also indicate that a single, often unaccompanied, highly-experienced angler was able to catch roughly 8% of the available fish on an annual basis. It is recommended that anglers adopt a precautionary approach and release all trout with a fork length ≥ 400 mm caught by trolling in Loch Rannoch.