Waipa trap reports – 2024 winter season
Introduction
Read reports of the Waipa Stream fish trap over winter 2024.September 2024
Rainfall monitoring equipment at the trap site registered 213 mm for September. A single flood event took the trap out of operation for 24 hours, suggesting fish could have bypassed the trap on their way upstream during this period.
Rainbow trout are still arriving in high numbers, with 474 processed this month. The data shows the number of hens in particular, remains very strong (292).
The longest rainbow was a jack measuring 600 mm. However, the heaviest was a 2.65 kg hen, with a fin-clip that confirmed it had also passed through the trap last year.
The number of migrating brown trout is really tailing off now, with only 3 hens contributing to the data. This is entirely expected, given browns tend to start their spawning migration earlier and finish earlier.
A growing number of trout are now returning to the lake after spawning, so increasing numbers are being processed through the downstream pen. This month we trapped 254 kelts compared to 170 in August.
Graphs and tables September 2024 (XLXS, 66K)
August 2024
Despite significant rainfall (245 mm) there were no flood events. Periods of consistent rain elevated flow levels without breaching the top of the fish trap, preventing trout from bypassing the trap.
As a result, the numbers of rainbow trout captured in the upstream pen was very high – quite literally off the charts. Our graphs accommodate up to 300 trout per category but on this occasion, we counted 410 Rainbow hens and 310 rainbow jacks. The combined total for rainbows alone was 710.
Browns start their spawning runs earlier than rainbows and finish first. The figures confirm their spawning runs have already peaked, with 64 hens and only 8 jacks recorded.
Rangers were kept very busy during elevated flows, with over 70 fish per day processed through the trap at times. These figures confirm the importance of this spawning stream and underline how many trout bypass the trap during flood events.
As we progress through the season, we expect to see an increase in the number of spent fish captured in the downstream pen. In August we counted 170.
Graphs and tables August 2024 (XLXS, 66K)
July 2024
Periods of significant rainfall ensured trout continued to migrate upstream in good numbers - 178mm of rain was recorded at the trap site, with no flood events.
This month we processed a total of 309 trout, only slightly down on the 332 fish recorded in June. July saw a slight increase in rainbows, up from 200 to 206, while browns dropped by 29, to 103.
Looking back to previous years, July 2024 rainbows were 24 mm longer and 320 g heavier than those trapped in July 2023. However, they were only 15 mm shorter and 90 g lighter than the exceptional rainbows trapped during July 2022.
July 2024 browns were 7 mm shorter and 40 g lighter than those trapped in July 2023 and 12 mm shorter and 340 g lighter than the solid browns trapped during July 2022.
The heaviest brown this month was a 3.25 kg jack, that had spawned in previous years and measured 655 mm. The heaviest rainbow was a maiden spawning jack of 2.8 kg and 590 mm.
Graphs and tables July 2024 (XLXS, 66K)
June 2024
The arrival of significant rainfall this month encouraged trout to move up into headwater streams. A total of 183 mm of rain fell at the Waipa trap site, with no flood events.
After a particularly dry May where only 49 trout were captured, June delivered an impressive 332 fish, offering encouraging signs for the winter season ahead.
Compared to June last year, slightly more brown trout were recorded but they were very similar in terms of average length and weight. Rainbows on average were 23 mm longer and 300 grams heavier than those trapped the same time last year. They also displayed a better condition factor.
There were 132 browns in total, with the heaviest weighing 3.95 kg. This large hen was 670 mm long with a condition factor of 47.4. Previous fin clips confirm she had spawned in the Waipa stream before and must be at least 5 years old.
The heaviest Rainbow was also a previous spawner. A jack which measured 600 mm, 2.6 kg and 43.5 CF.
Graphs and tables June 2024 (XLXS, 66K)
May 2024
The Waipa spawning trap was recommissioned for the 2024 winter season in May. The trap is located on the Waipa stream, a tributary of the Tongariro River. The stream is an important spawning tributary for both brown and rainbow trout.
The 27 consecutive year of trap operation got off to a quiet start. In-stream conditions were low and clear, with no heavy rain or flood events recorded. Only 117.5 mm of rain was measured at the Waipa trap site and there was a period of 20 consecutive days with no rainfall recorded at all.
With stream levels more reminiscent of summer, the numbers of migrating trout in headwater streams were reduced. This is clearly illustrated by comparing the May 2023 data, when we experienced over three times the rainfall.
Brown trout migrate before rainbows, but their numbers were low this May. Only 16 were recorded for the month. The largest was a 620 mm jack that weighed 3.1 kg.
A total of 33 rainbows were captured. The largest was a hen of 570 mm and 2.2 kg. The fin-clip pattern confirmed this fish was at least 5 years old.
Each fish is carefully processed before being released upstream. This written summary along with the accompanying spreadsheet, provides anglers with a snapshot of the trap results.
Data from our Autumn Lake Productivity survey confirmed high productivity in Lake Taupō, therefore we anticipate trout numbers will increase significantly with the arrival of rain.