Surely any trout prepared to eat rats or mice swimming on the surface would have to be a good size fish. Just last year during the Canterbury high country opening weekend a rat shot out from the matagouri scrub that grew almost to the water’s edge of a lake I was fishing. To my surprise, and for no apparent reason, the rat swam out into the lake. Indignant at its impertinence I threw a stone in its direction.
To my further astonishment it dived under eventually surfacing some 15m out parallel to the shore. It swam along for a short time before again diving under. When swimming on the surface it left a sizable wake on the otherwise still water. Once more it surfaced parallel to the stony bank by now much further away. Eventually it returned to dry land some 50 odd metres away from where it had first gone in. Why it should suddenly decide to take a dip in this way I can’t imagine.
There has been much discussion among New Zealand trout anglers in recent years about the link between beech trees flowering and the subsequent massive increase in the mouse population. Although some beech trees flower every year, it is only once in every 3 to 5 years that excellent climatic conditions cause them to produce a huge increase in flowers; followed by dropping of their seeds the following summer. This sudden massive flowering of beech trees is known as a mast year.
With so many seeds on the ground the following summer the mouse and rat population rapidly multiplies to plague proportions. Many back country trout, that are normally long and slabby, suddenly fatten-up big time on their new high protein diet of live rodent. Why the rats and mice should readily take to the water, and why some trout seem to be able to feed in them almost exclusively is a mystery.
Some years a similar massive tussock seeding occurs which also sees a huge increase in rodent numbers.
While a few purist trout anglers may prefer to distance themselves from fishing a bulky mouse imitation most have no hesitation in fishing such a pattern – myself included. Many a fly tyer will also “have a go” at tying a deer hair mouse imitation thinking it unlikely that such a fly might actually catch a trout; or that they will ever get the opportunity to “match the hatch” with such an imitation!