In one location, the Tadnoll Brook in Dorset, trout stomach contents were examined frequently throughout the year (by gastric lavage or stomach flushing, a non-destructive method) allowing the team to determine variability in the reliance of trout on terrestrial prey inputs. Approximately 50% of trout diet was made up of terrestrial prey but this figure increased to as much as 90% in the summer months.
“There are some established rules that allow ecologists to predict the abundance of predators or prey within food webs. Feeding on terrestrial prey allows the trout to gain additional energy and hence bend these rules” said Dr Dan Perkins from the University of Roehampton, the lead author of the study.
Brown trout can be found in at least 50 countries across the globe and are an economically valuable resource; this supplement to their diet is thought to be important in explaining their maintenance of populations across such a widespread distribution and their ability to (re)colonise systems shortly after environmental disturbances.
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