Otamangakau: New Zealand’s Jurassic Lake

OTAMANGAKAU:

New Zealand’s Jurassic Lake

It’s not really a lake, nor is it a river, despite having a subtle west to east flow. Despite the identity crisis, this small body of water is commonly classified as one of the hottest pieces of fly fishing real-estate on the planet!

By ANDREW HARDING

No, we’re not talking about the huge mouse eating browns of New Zealand’s South Island, but a tiny, manmade water-storage dam located in the shadow of the majestic volcanic peaks of New Zealand’s central North Island. It’s beautifully barren, epically isolated, and the trout? Magnificent in condition and size. It’s Otamangakau.

Pronounced (O-ta-man-ga-cow) or simply “Ota” to us kiwi’s, New Zealand’s answer to Jurassic Lake, albeit a fraction of the size with an average depth of only one meter! It’s a sensational fishery for those lucky enough to live here, however the lake receives relatively low angling pressure in the broader scheme of things. Ota’s makeup of 50/50 browns and rainbows makes for some exciting fishing, stalk the edges in the morning for the numerous, big, tailing browns, or hit the channels in the afternoon for some ridiculously proportioned rainbows.

Tailing browns

For myself, it’s the tailing browns that are the major drawcard. Through the warmer months of October through

to March, these browns with an average weight of around 6-7lbs take to the lake’s shallow silty margins in substantial numbers, their huge paddles waiving like excited kids in mere inches of water as they grub around in the mud for bloodworms and anything else that catches their eye. But don’t be lulled into thinking these browns are easy to catch, they aren’t…You’ll need your A game… coupled with 20ft plus leaders and a stealthy approach, even then expect refusals 90% of the time.

When you do eventually hook one of these fish, the tradeoff is you would have had to use a light tippet to induce the take - now have fun with said tippet when that brown makes a run headfirst into the nearest weedbed… the struggle is real… obviously, a long-handled net is an advantage!

Cracking the code

It took me a good 10 years to crack this lake, and I still know many who’ve not caught a fish in it! The potential for a trophy fish, over the magical 10lb mark is high, especially when fish are in peak condition around January.

Most anglers like to fish the lake from a form of watercraft, drifting nymphs under huge indicators… not really fly fishing at all in my eyes,… Me? I love going shore-based! The lake edge fishing is sensational and a hell of a lot more fun than staring at an indicator bobbing round for hours on end, in the hope that a cruising rainbow will snaffle one of your nymphs.

Huge paddles waiving like excited kids in mere inches of water

The one caveat is the mud will try and suck you down to a watery grave. The wading is very difficult if you’re not able bodied, and somewhat fit. Twice the mud here has nearly claimed my life, so it’s something not to be taken lightly.

A memorable fish

My most memorable fish from ‘Ota’ was a rainbow funnily enough, despite the browns being the larger of the species in general, my Norwegian friend and well known trout-bum, Andre Hesslewroth and I were firing Damsel nymphs on a January afternoon at the numerous cruising browns along the shallow weed margins.

A swirl here and a cast there, we were certainly nailing a few beautiful browns between 5 and 7lbs each - it was a great morning.

The potential for a trophy fish, over the magical 10lb mark is high

The gentle current dislodging damsels off the weed edges into the jaws of marauding trout. A distant fin cutting a swath through the mirror calm surface on the weed edge caught my eye so wading just a little further… I fired a cast a meter or so ahead of the fish, strip… ON!

The fish in Ota really do pour-on the gas when something lands near them to intercept it. From the initial run, THROUGH the weed-bed and out the other side into the channel, she jumped, (well I think it was a she. To this day I’m still not sure! It’s not as if that kype was a defining feature).

Andre turned to me with a sly grin and muttered… it’s big… With only a few turns of backing remaining, I was inching forward, I still don’t know how I managed to coax her through the weed… As she touched her belly on the shore all hell broke loose, a swift net shot by Andre and I’d won…. a stunning fish, not huuuuge, but a 5kg lump of stunningly conditioned and proportioned rainbow, and still my biggest rainbow to date. It was such a great experience, made even better by being able to share the moment with Andre.

A remote alpine basin

Ota’s downfall despite it’s high elevation, and sitting in a remote alpine basin is the one thing you wouldn’t expect… a lack of wind! It really is very sheltered. The mirror like surface on most days sees fish on midges, taunting and teasing anglers in a cruel fashion. When it’s calm, it’s tough! The lake fishes best in foul weather, the worse the weather?

The better the fishing, you know?… the usual story with lake fishing.

Whilst Ota is predominantly what I call a “strip, strip, bang” fishery, this method of using floating lines and small damsel imitations or Woolly Buggers is only effective with some surface ripple, when it does calmoff it’s time to target fish with a dry / dropper on the weed edges.

With a dropper no more than around 10cm, this is an excellent method for picking off fussy cruising browns and a hell of a lot of fun!

As with any dry / dropper fly fishing, you’ll encounter that odd fish who’ll prefer to snaffle your dry and ignore the unweighted nymph dangling below. They aren’t overly fussy on patterns, just size.

Dry Time

Come January through March, it’s dry time! Whatever huge rubber legged concoction you have in your fly box is never big enough! The abundant, but short-lived cicada hatch spurring the trout to feed with reckless abandon.

“I’d gone through every manner of cicada imitation and rubber-legged behemoth I had”

Unfortunately, this is a blind method, the fish moving so fast, it’s near impossible to spot them or intercept their path, but they will take a huge dry drifted blindly around the cooler inlet water, where the upper reaches of the Whanganui River enter the lake by way of a man-made canal.

A fresh cicada pattern, please!

A few years ago on Ota we encountered what can only be described as an epic cicada hatch. These bumbling fat “cheese-burgers” were being blown into the lake in their thousands by the strong, warm, northerly breeze. It was ON!!

Browns and bows averaging 6lb + were coming in thick and fast. One of those times in your angling lifetime, you simply pinch yourself and ask ‘can it get any better than this”?

After a bust-off in the weeds, I reached for a fresh cicada pattern, only to find that WAS my last one! I’d gone through every manner of cicada imitation and rubber-legged behemoth I had!!!! Arrrggghhhhh!!!

With huge trout breaking the surface in every direction, and in desperation I tied on an olive #10 Woolly bugger, snipped off the tail and scissored through the soft hackle… loaded it up with a good dose of floating… and we were back in business. It didn’t matter what I used, the fish were grabbing this improvised dry-wolly-worm-cicada just fine! I guess a lesson gleaned from that day is there is always a way to improvise with existing patterns given a quick nip-tuck!

Dormant and waiting

Ota is quiet now, there is no overseas pressure thanks to “that” flu, much like the rest of New Zealand. She’s lying dormant and waiting, the fish are getting more numerous and larger year on year, it’s a fascinating aspect to see despite the Department of Conservation hinting they are about to put measures in place to stem angling pressure when the lake surface temperature reaches 20 degrees Celsius, closing to all fishing at short notice.

Whilst mortality comes as a given on any highly pressured body of water, the lake is so healthy it can sustain it – in my humble opinion, and even somewhat benefit from it. It’s a densely populated and extremely healthy system and can certainly cope with such factors.

As I’m writing this; a message has come through to my mobile from a friend “about time we hit Ota again?”… my arm is made of rubber you know… loading up the camper van and heading to my “happy place”… We’re so very lucky to live in New Zealand with angling destinations such as Ota on our doorstep.