Taupō Fishery Focus.
By trout anglers for trout anglers.
Issue 39 – February 2025.
Late Summer and early Autumn is a great time to visit the Taupō fishery, with a variety of fishing on offer. From large browns moving into rivers, to chunky chrome rainbows packing on weight in the lake, anglers are spoilt for choice.
Rivers are running low and clear at present so trout can become quite fussy. As you might expect under these conditions, a cautious approach will reap the best rewards. These selective fish will respond to good presentation, long leaders, and smaller flies. Where possible, take time to sight fish and be willing to move so you can more effectively cover a fish. Cicada’s have been prolific this year, but colder mornings are starting to take a toll. Anglers may find an occasional trout willing to hit a large fly, but selective trout are far more likely to respond to smaller flies including small lacewing patterns.
Lake Taupō is fishing well with some excellent maiden fish coming to the net. The thermocline is well established, and trout are actively hunting in this zone during the day. Therefore, anglers should fish deep and target water where the lakebed is around 35m to 40m below the surface. Early morning and evening, trout will feed in shallower water giving lake anglers an alternative approach. River and stream mouths are also a great option at either end of the day, with trout attracted to the cool oxygenated water and plentiful feeding opportunities.
Local fishing tackle stores are an encyclopaedia of local knowledge, so make sure you pop in and get the latest tips on flies and lures.
Iconic trophy trout venue Lake Otamangakau reopens to fishing on Saturday 1 March after being closed for February. As the water cools, trout will be actively feeding in preparation for spawning. We have heard a few concerns from some anglers about the merits of the February closure. To help reassure these anglers, we have included an article in this newsletter that sets out to explain why the closure is important.
It remains important to harvest trout from Lake Taupō. The latest data suggests the average catch and release percentage currently sits at 34.8%, which is similar to 35.8% for the previous summer. This figure is nudging in the right direction, but there is plenty of room for improvement.
A new licence sales platform may be on the way, but our current website remains a great place to buy your fishing licences. The online licence store is open 24-hours a day, seven days a week and has a variety of licence options to suit different circumstances. Always make sure you have a valid licence before you start fishing – www.doc.govt.nz/fishinglicence
Tight lines.
James Barnett
Editor
Snapshot from summer creel surveys.
Creel surveys are a good management tool that helps us identify how many fish are being harvested from the Taupō fishery. The survey questions also shed valuable light on catch rates, preferred fishing methods, size and condition of trout, and angler satisfaction. This data when combined with information from our other technical studies, helps us understand how the fishery is performing.
As of the end of January 2025, Fishery Rangers had undertaken 106 angler surveys on Lake Taupō – for the 2024/2025 summer period. A short report was created to provide a summary of the data collected and compare it with data from the same period captured over the last eight years – going back to summer 2017/18.
Jigging remained the most popular method for fishing the lake, with 45% of those surveyed jigging in 2024/25, which is on par with the previous summer. Deep trolling with lead lines (28%), shallow trolling (14%) and downriggers (7.5%) largely accounted for the rest and, again, these numbers are similar to the same period last year.
For more on the survey results and to discover what this data tells us about the quality of fishing in store for anglers over coming months, head to our web story>
Lake Otamangakau reopens.
Lake Otamangakau will reopen to fishing on Saturday 1 March. After a hot February where the surface water temperature sat above 20 degrees for long periods, we are finally seeing figures start to drop. March can still deliver periods of hot weather, so we recommend anglers continue to monitor water temperatures using the live telemetry data graph on our website>
This summer has seen the return of more typical hot February weather after the cool February we witnessed last year. The closure will have provided the valuable protection needed for large trout. These trout will be feeding avidly now as they look to build up weight and condition in preparation for spawning. Insect activity will remain high in March, particularly damsels that are often prolific at this time of year, providing plenty of opportunity for trout and anglers.
A detailed account of the February closure can be found in this newsletter.
February closure at Lake Otamangakau.
This article addresses concerns that anglers raised with Taupō Fishery Rangers during recent angler surveys, as well as emails and comments posted on social media. The information aims to help anglers further understand why the February closure was introduced and how it protects this very special and unique trophy trout fishery.
Background.
Firstly, we should reflect on why change was needed. During the summer of 2018 anglers reported increasing numbers of dead trout at Lake Otamangakau. This sparked a body of research into what could be causing these deaths. At the time, it was thought that marginal environmental conditions such as high summer water temperatures and low dissolved oxygen and/or poor catch and release technique could be the main causes. Sampling the water temperatures throughout the water column in some of the deepest sections of the lake commenced along with logging dissolved oxygen to determine what was actually happening under the surface. In addition, a timelapse camera was set up to quantify angling pressure over the fishing season. This was followed by a catch and release study on the lake to monitor the survival rate of fish after being caught during cold, average and warm water temperatures.
This research, combined with feedback from the angling community, informed the new regulations, including the February closure.
February closure.
February is the last month of summer on the meteorological calendar and traditionally the warmest month of the year. It is also the time of year when surface activity at Lake Otamangakau is at a peak, with swarms of damsels, cicadas and other invertebrates. So why close the lake to fishing in February?
Insect activity is high in February for a reason. Water temperatures also reach their peak, with surface temperatures regularly exceeding 20oC, promoting huge insect activity. Critically, this temperature can be lethal to trout. At this temperature, catch and release fishing becomes impractical, if not unethical. Prior to the introduction of the February closure, the typical warm water conditions would regularly result in large dead trout floating around the lake edge.
As water temperature approaches 20oC the chance of trout mortality increases even with proper catch and release techniques. Trout already weakened by heat stress are at risk and can die no matter how carefully they are handled. The warm water phase of our catch and release study confirmed that Lake Otamangakau trout only had a 60% survival rate when released. Stopping fishing during the hottest month of the year will reduce unnecessary post-release mortality and protect trout when they are most vulnerable to heat stress. Under these circumstances we should put the wellbeing of large trout ahead of an angler’s desire to just go fishing. Without these trout, there will be no anglers.
Shallow lakes such as Lake Otamangakau are sensitive to temperature fluctuations due to the high surface to volume ratio. They have less water to absorb heat and so they warm up faster. Sunlight can penetrate through most of the water and heat the entire water column. Shallow lakes mix easily allowing the entire body of water to warm up rather than just the top layer. They are also more affected by air temperature and wind due to less thermal inertia. A dark muddy bottom can also absorb heat and transfer it to the water.
Lake Otamangakau shares many of these characteristics and tends to heat up during December and early January, then hold its heat like a bathtub during February before returning to more favourable temperatures in March.
This summer, the average daily surface water temperatures exceeded 20oC for the first time on 17 January 2025 and maintained this high average well into February. The maximum daily surface temperature reached 20 oC for the first time on 10 January. During the period 16 January to 28 January, the average maximum surface temps averaged 21.2oC and ranged from 20.3-22.1oC.
In an ideal world, the fishery would have been closed this year during the latter half of January, as surface water temperatures were already dangerous for trout. There was always going to be a risk with closing the fishery during February only, as late January and early March could also see days where water temps regularly exceeded 20 degrees. However, a 4-week closure was a good compromise, giving trout a break for a month while the lake is typically at its warmest. This approach also provided clarity for anglers, allowing them to plan fishing trips – especially those travelling from overseas. Having a system that was fully temperature dependant could realistically mean no fishing from mid-January through until early March and so a February closure was the best compromise for both the trout and the anglers.
A ‘hoot owl’ style regulation concept, as used overseas to limit fishing during the heat of the day, is hard to manage and police on an hourly and daily basis. Moreover, when we looked at day to day temperature variation a large proportion of the time would not have been suitable for fishing as it was warmer than 20oC. (Fig.1). Looking purely at the period 5am to midnight, 30.7% of January and 78.6% of February saw surface water temperatures at 1m deep, exceed 20oC.
The time of day (5am to midnight) that the temperature exceeded 20oC was also examined (Fig.2). During January, there were a total of 6 days where the water had already exceeded 20 degrees before fishing is allowed to start – 5am. Temperatures then hit 20oC between 9am and 3pm during 7 days with two of those days reaching 20oC around midday. The last day saw the temperature reach 20 degrees as late as 5:45pm. This highlights the difficultly in using a hoot owl closure concept as the time of day where temperatures exceed 20oC is not consistent. Planning fishing trips around fluctuating temperatures just isn’t practical.
The time of day when the temperature peaked was not consistent either with temperatures peaking at midnight, midday, mid-afternoon and evening over the period of just a few days. In general, the lake temperature would decrease slowly between midnight and 9am before warming with the effect of the sun until about 3pm, before starting to cool down slowly again towards midnight.
It is also important to remember that the surface water temperature we record is taken at 1m below the surface in 10m of water. Shallower parts of the lake will be well above 20oC and so our temperature monitoring provides a fair guide for how warm the lake generally is as a starting point. Anglers rarely fish in the deepest sections of the lake and so they will be targeting trout in waters 5m or less and so surface water temperatures will be even warmer in these shallower locations.
On the plus side, the fish and the anglers get to rest for a month and a new “opening day” is created on 1 March. If water conditions are favourable anglers and trout can resume battle, where released trout stand a much better chance of survival. One downside we noticed to the February closure was the final rush of anglers and boats towards the end of January, squeezing in a fishing session before the fishery closed, irrespective of what the water temperature data was indicating.
Water temperatures at 1m depth and at 10m depth are automatically logged with readings taken every 5 minutes which produces 288 individual readings during a 24-hour period at each depth. The 1m temperature readings were averaged each day and plotted in Figure 3. The orange line representing this summer which saw the average daily temperature stay above 19oC from mid-January remaining above 20oC until the third week of February. This is in stark contrast to the blue line representing early 2024 which was unusually cool.
The difference between the maximum and minimum daily temps was calculated and averaged for each month to determine the average daily fluctuation (Table 1). This summer, December saw the lake surface warm daily by an average of 2.5oC with a range of 0.9 to 5oC. January saw an average daily temperature difference of 1.7oC with temps ranging from 0.4 to 3.9oC. February recorded an average of 1.2oC with a range from 0.5 to 2.6oC. Daily warming of the lake by as much as 5oC is significant. As expected, daily temperature fluctuations at 10m depth were much less than at 1m depth, with an average of 0.6oC in December, 0.8oC in January and 0.6oC again in February. The largest temperature difference in December was 3.3oC followed by 1.6oC in January and 1.1oC in February.
The heating effect of the sun on the water column can be seen by looking at the daily difference between the 1m temperature readings and the 10m readings. This difference averaged 2.4oC in December and almost 4oC in January with daily differences varying by as much as 6.7 degrees in December and 7.5 degrees in January between the top and bottom of the lake at one of its deepest points. This heating effect will be even more extreme in shallower water.
Predicting what the weather will do from one day to the next has its challenges in NZ, let alone forecasting what the weather will be doing in several months’ time. The February closure is timed to capture the most intense period of heating and is there to protect the trout when they are at their most vulnerable. The previous two summers were much cooler than normal. However, this summer saw a return to the more typical water temperatures and so the closure delivered the protection trout needed.
The future
Looking ahead, we will continue to monitor the lake closely. This includes angler surveys, water temperature monitoring, and capturing spawning data from the fish trap. In addition, we are keen to understand how many times a specific trout is caught and released during a fishing season. A tagging programme could be a good solution to capture this data.
Renowned angler Lee Wulff once said, “A game fish is too valuable to be only caught once.” This is certainly true for the trophy sized trout in Lake Otamangakau.
New licence sales platform progressing.
Before Christmas we announced that a new Taupō fishing licence sales platform was under development. With a new season just around the corner, work on the platform is continuing at pace. The new platform will bring system stability improvements as well as enhanced services for anglers and is due to be completed in time for the start of the 2025/26 fishing season.
In line with other modern online sales platforms, purchasers will be able to create a ‘user profile’ that will allow them to manage their account. Short duration licence purchasers will be able to choose a fast-track purchase option if preferred.
The Taupō fishing licence structure and costs will remain unchanged, although the high software development costs required to recreate the sales agent service means this facility will no longer be available. This means anglers will no longer be able to purchase Taupō fishing licences from fishing tackle stores or other outlets.
Over 80% of Taupō fishing licences are already purchased using our online fishing licence store – which is open 24-hours and day, seven days a week, and can be accessed from anywhere with a good cell phone signal. The new platform reflects the growing demand for online services and will offer convenience as well as better functionality and greater reliability for anglers.
We will continue to share updates on the new platform as we get closer to the new fishing season.
Waipa Trap upgrade, Phase 2.
The Waipa stream fish trap has been operating each year since it was created in 1998. The Waipa Stream was chosen for its stability and isolation along with its reliable spawning populations of both brown and rainbow trout. It flows into the upper Tongariro River near Rangipo. It is a very important tool to help monitor the adult trout population with several thousand trout measured and weighed each year.
Last year, Phase 1 repairs were completed on the true left bank. This involved replacing the aging timber walls and reinforcing the gabion baskets. This year saw further repairs carried out to the true right bank with new timber being added.
This work is best carried out during the summer months. The headwater stream is much shallower due to low summer flows, the water is slightly warmer making it easier to work and there are very few adult fish to disturb. The old timber was still sound in the centre but years of exposure to moisture, frosts, and floods had taken their toll on the exterior.
The fact that the timber and metal structure has survived almost 3 decades is testament to those that initially designed and built the trap. With both timber sides now complete, we will look to strengthen the existing gabion baskets, making the structure strong enough to endure another 30 years of trapping!
Photo competition.
The annual photo competition is a great opportunity to celebrate the many faces of the Taupō trout fishery as we build up to a new fishing season. Every year we look for a winner to reflect each licence category, with one going on to claim the overall spot and feature on the printed plastic licence.
Last year the overall winner was a great photo that captured how three generations of the Clement family came together to spend time trout fishing on the Tongariro River. Other recent winners have included a dramatic photo of an angler holding a trophy brown from Lake Otamangakau, the intensity of catching a big winter rainbow on the Tongariro, and a mother and son holding a pair of rainbows following a double hook-up at The Delta.
The competition is not just about fun and bragging rights. All the winners receive a prize – a Taupō season fishing licence of their choice, up to the value of $159 (Family Season).
So, keep snapping and look out for the launch of our photo competition.