Zane Mirfin – Mice, Rats & Rodents
Mouse feeders are often easy to identify, with wide thickset flanks, big full bellies with hard nugget-like chunks being able to be felt from the outside…
Huge New Zealand trout feasting on rats and mice are the stuff every trout angler dreams of. Big, fat, heavy brown trout, engorged on a turbo-charged, proteinrich diet of rodents are something to marvel at and enjoy. But it only happens once in a blue moon, in those special years when the native beech forest produces an abundance of surplus seed, which causes rodent populations to explode in number.
Most New Zealand trout are limited in size by the food available to them. Many trout streams here have limited fertility and are not the insect-rich waters that premier overseas waters often are. So, when they get a bumper terrestrial food source, trout are only too happy to take advantage of it.
Recently, I read reports in the Nelson Mail about increased catches of rodents and predators by volunteer trappers in the Brook Waimarama Sanctuary area. I also noticed a few more rodents around my garage this winter before I put out bait stations, with the excellent name of ‘‘departure lounges’’.
With the general trout fishing season due to open on October 1, I’ve been busy fielding inquiries from international anglers interested in the fishing prospects for the coming season. Reports from Nelson Lakes Conservation Department staff would indicate that a spectacular beech seeding in autumn has paved the way for a substantial increase in rodent populations in the spring and summer.
New Zealand rodents range from small to a massive 30 centimetres for a big norway rat. Rodents are prodigious breeders and a female rat can produce 12 litters of 20 rats each year, according to pest contractors Target Pest, potentially having the ability to have thousands of descendants a year, which is a lot of trout food.
When rodent populations boom, their predators, such as stoats, ferrets and weasels, also peak, which is bad news for native birds and invertebrates, which suffer when rodent numbers abate. Cuddly little critters such as rats and mice don’t get a lot of positive press from government organisations and the media, but they are actually pretty interesting animals and, whether we like it or not, they are part of the history of humanity as well.
European history is richly laced with tales of rats and mice. In New Zealand, rats were of cultural importance well before Europeans arrived on the scene, with kiore or Polynesian rats being a treasured part of Maori culture, having spiritual value to some iwi. Maori considered kiore a delicacy. Rats fattened on a diet of berries and invertebrates were trapped and preserved in their own fat for those cold winter days, long before Walt Disney’s Mickey Mouse, Ratatouille or self-styled love rat Major James Hewitt.
Over the years, I’ve been fortunate as a recreational angler and professional fly-fishing guide to have been involved in the capture of an unfair share of very large brown trout, many of which have been fattened on rodents. Some seasons’ trout will be 1kg to 2kg heavier than normal in many rivers, and we all dream of trophy trout 4.5kg and bigger.
So how do the mice and rats end up in the water? It seems rodents range far and wide nocturnally for food, move to new territories, die of hypothermia, drown, and fall or swim in rivers and so become available as trout fodder.
Most mouse-fed trout are caught on traditional tackle offerings such as dry flies and weighted nymphs during the daytime, although we have caught trout on mouse imitations fished during the night shift. Slow-stripping a large floating deerhair mouse imitation across a still pool after dark can provide exciting fishing, although, interestingly, the trout usually take the mouse imitation quite softly.
Rubber mouse imitations or other topwater poppers also work well on spinfishing gear, with the advantage being that anglers can cover larger distances with longer casts and also avoid standing in the water among the eels. Mouse feeders are often easy to identify, with wide, thick-set flanks, big full bellies with hard nugget-like chunks being able to be felt from the outside of the fish. Trout can eat multiple rodents and fish with up to several dozen mice inside have been recorded.
Sometimes with rats, I’ve seen a rat’s tail hanging out of a captured fish’s mouth. I remember one captured trout regurgitating dead mice in the net. Big trout act like a magnet to overseas anglers and word of big fish present will prompt many anglers to book longer and more adventurous trips.
One overseas fishing agent is already playing the mouse card, with worldwide recession and lower than normal bookings requiring different strategies to attract high-value, big-spending tourist anglers. Personally, I’m waiting until I get on to the water and have a look around this coming fishing season before I talk too much about mice and rats. If the hype fails to match reality and the big fish just aren’t there, a river can be a lonely place as you attempt to be a modern-day Rumpelstiltskin trying to spin straw into gold.
Secretly, however, I’m hoping a big rodent year will happen and that the big trout will appear like magic. It might be tough on the native birds but the trout fisherman in me says ‘‘bring on the mice’’. Let’s just hope the Department of Conservation isn’t crying wolf – or in this case, rodent – because, when you’re a hardcore trout bum, you can never have too many mice. Hickory, dickory, dock.