The fishery

To: John Gibbs Manager Department of Conservation Conservation Fisheries,

Private Bag Turangi

Copied to: Graham Whyman, Lake Taupo Fishing Advisory Committee,  Sporting Life, The Mall, Turangi.

From: The Advocates for the Tongariro River Inc., Po Box 335 Turangi

Date: 13th September 2007

Introduction

1.     The Advocates committee wishes to thank you and your staff for meeting with us to

Changing the minimum legal length of trout

2.     The Advocates Committee accepts the case that has been put by the fisheries management for changing the minimum legal length of trout from 45 to 42cm. We are aware that in the history of the Fishery changing conditions have, at times, necessitated changes of a similar nature.

3.     However, downsizing the minimum legal length, as an action on its own is not sufficient as it fails to address the causes contributing to the diminished size, number and condition of trout.

Observations

4.     A large number of anglers are expressing concern about the diminished size and poor condition of trout.  These observations which have been made over the past two or three seasons and calendar years, have increased markedly this year. There is no doubt that the trout are smaller, are fewer in number and a significant number are in poor condition. These fish are not juveniles. They are mature fish spawning as part of the winter run.

5.     Fisheries staff have suggested that we may be experiencing the effect of a late season, with the good fish yet to come. We consider this unlikely to be case, as regular spawning activity has been evident in the river over the winter months and an increasing percentage of fish caught are spent and returning to the lake.

6.     Soft data has come to our attention in the form of reliable observations, that large numbers cat fish inhabiting the lake are bigger than expected and stomach contents show them to be feeding heavily on smelt. These observations have been made around the Kuratau cliffs and at the Delta.

7.     It is likely that catfish pose a greater threat in competing with trout for food than has hitherto been acknowledged, given the characteristics of their feeding habits. And it is reasonable to suppose that the cat fish population has increased to a point where food sources are no longer sufficient for trout.

8.     There can be no doubt that the reduction in trout size, numbers and condition, as observed in both the river and the lake throughout at least the last year or two, is a consequence of trout  getting insufficient food.

Request for more monitoring and analysis

9.     To the best of our knowledge the most recent comprehensive research done on trout food source was that done in 1986 by Theo Stevens. We think it is necessary to have comprehensive current data on food sources and factors relating to associated eco systems, in both the lake and the River.

10.   We note no discussion or information on the biota, as opposed to available species in eco systems which are readily available, and would like to see such data gathered and analysed.

11.   The Taupo fishery has been traditionally known for its trophy trout.  Can we conduct research to indicate whether this particular gene pool has been depleted?

12.   We urge fisheries scientists to undertake more extensive monitoring of catfish. For example, monitoring at a greater number of locations and a greater range of depths to get better data on relative numbers of catfish and the extent to which their consumption of smelt, Kura and fingerlings, is impacting negatively on the condition and sustainability and of the trout population.

13.   Once comprehensive data on food supply and the factors impacting on it has been gathered and analysed we would like the information to be in the public domain and used by fisheries scientists as a basis for corrective intervention.

Our Request for Information

14.   We would appreciate receiving information about :

i.    monitoring currently being done in the Lake and rivers

ii.   monitoring systems being used

iii.  whether fisheries scientists are confident that current monitoring is producing the data necessary for well informed management of the fishery

iv.  the extent to which resource constraints are limiting the gathering of data considered necessary by fisheries scientists.

Intervention to redress unfavourable conditions

15.   There are a number of recorded instances in the history of the fishery where intervention has been necessary due to ecological changes that were producing unfavourable conditions for trout. And it is interesting to note that such interventions produced successful outcomes. Indeed among the successful interventions of the past was the introduction of the “wild” trout now populating the fishery. The Advocates Committee would therefore reject any contention that intervention is not acceptable. Where it can be shown as necessary to sustain the health and quality of the fishery, interventions such as those made in the past, are essential.

16.   If food supply is found to be a  cause of the observations noted in this submission, we suggest a two part response.  First, and as soon as possible that a significant injection of smelt be put into the lake to augment what is clearly an insufficient source of nourishment for trout, and second, that comprehensive data gathering be undertaken to determine the reasons contributing to the problem.

Conclusion

17.   The Advocates would like to meet with you and your team around Easter 2008, at a date to be agreed nearer the time, for an update on progress on the matters included in this submission.  In the meantime we would be pleased to receive information on monitoring, as requested in paragraph 14.