Waipa spawning trap

Image: James Barnett | DOC

Introduction

A series of monthly reports sharing information gathered from the Waipa Stream fish trap.

Highlights

Located on the Waipa Stream, the Waipa spawning trap is positioned within a significant spawning tributary of the Tongariro River, 24 km upstream from Lake Taupo.

Fishery Rangers record the numbers of trout, their sex, length, weight and iteroparity (how many times individual fish have spawned). From this data we also determine a Condition Factor, which reflects how much food has been available to the trout.

This trap has been operational since 1998 and has provided a valuable long-term data set. We view this information in combination with a variety of other studies such as angler surveys, drift dives and lake productivity work, to ensure a broad understanding of fishery's health.

Date:  23 October 2020

Below are links to monthly reports from the Waipa trap. These are presented as graphs and tables for each month, with the previous month and same month of last year included. 

Each file includes the below data for brown and rainbow trout (male and female):

  • count
  • average length
  • maximum length
  • average weight
  • maxium weight
  • condition factor.

Reports from 2020 winter season

September 2020

The excellent season continues with the number and condition of trout higher than recorded in September last year. The overall figures may be down compared to the previous month, but this aligns with expectations and simply indicates we are past the peak of the annual spawning run.

We also experienced three flood events, which will have allowed some fish to bypass the spawning trap. Fishery scientists will have a clearer idea of how many migrating trout were missed when monitoring is complete on the downstream pen of the trap – fish that were missed will not have been fin clipped.

Brown trout have largely completed their spawning activities and those encountered in the trap could well have already spawned below the trap and are now seeking food further upstream.

The ongoing improvement in the Rainbow trout data (compared to previous years) further supports the experiences of anglers, who report they are having an outstanding fishing season.

Graphs and tables September 2020 (XLXS, 66K)

August 2020

Positive trends continue with the number of trout processed this month eclipsing those encountered during the same period last year – we processed 241 trout compared to 107 last year.

Average lengths are tracking similar to last month but again exceed last year’s figures. The same is true for weight and Condition Factor (CF). Almost all average weights and CF figures were the same or higher this year compared to 2019. The only exception is Brown Males (BM), which may not have been as large as this year but were in outstanding condition in 2019.

Graphs and tables August 2020 (XLXS, 75K)

July 2020

The number of trout recorded this month is nearly double the number measured in July 2019 (298 trout compared to 177). Numbers are also slightly up on last month, despite the relatively low rainfall experienced in July.

Rainbow trout continue to be heavier than previous years with males doing particularly well. Their high Condition Factor (CF) is also better than previous years - exceeding the excellent CF recorded  last year.

Graphs and tables July 2020 (XLXS, 67K)

June 2020

The data gathered this month reveals trout were present in both greater numbers and increased sizes, when compared to the previous month. Average lengths and weights are greater for both species and sex - brown and rainbow trout, male and female. The same is true for maximum size and weight.

Rainbow trout are heavier than we’ve seen for several years at the Waipa spawning trap, with females averaging 2 kg and males 1.7 kg. This aligns with reports from anglers and the wider fishing community.

The largest fish recorded this month was an excellent brown jack that measured 710 cm and weighed 4.7 kg.

Graphs and tables June 2020 (XLXS, 67K)

May 2020

Due to COVID-19 restrictions the spawning trap was not reinstated until the middle of the month which significantly reduced opportunities for data collection.

Therefore, it is no surprise to see fish numbers down on the previous year as this has reduced our sample size.

Lengths and weights are within the expected range, with a visible improvement in the Condition Factor (CF) for Rainbow males (RM).

Limited sampling opportunities combined with low headwater rainfall this year (80 mm May 2020, compared to 230 mm May 2019) may have impacted the results.

Looking ahead, it will be interesting to see how the excellent fishing experienced by anglers in the lower river translates into data collected from this headwater location.

Graphs and tables May 2020 (XLXS, 67K)

Reports from 2019 winter season

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