Date 15 March 2012
FEARS OF BROWN TROUT CULL UNJUSTIFIED
Recent articles in the Department of Conservation’s Taupo fishery newsletter, Target Taupo, have led to a great deal of discussion in the local and social media arenas. While much of this debate has been well informed, there are some misconceptions about the department’s plans to investigate re-instating the winter runs of rainbow trout into the Tongariro River. The purpose of this statement is to clarify some of the misconceptions and misinformation which have been circulating, and to bring some balance to the discussion.
The idea that the department intends to cull brown trout to help the rainbow trout runs recover, which has received widespread comment, is both incorrect and ill informed. While brown trout do eat juvenile rainbow trout, and their offspring do provide competition for juvenile rainbows, they are only one of a number of possible reasons for declining numbers of early running rainbow trout in the Tongariro River. As fishery managers the department recognises the value of the brown trout fishery in the Tongariro River, and that it is worthy of protection as the world class angling opportunity that it represents. The department does not have any intention to undertake culling or any other sort of control of the brown trout population.
The Lake Taupo trout fishery is classed as a wild fishery as it is sustained by natural spawning and does not rely on hatchery releases or stocking to ensure sufficient numbers of trout for anglers or for reproduction in future years. However, for a number of different reasons including environmental factors, the timing of the traditional winter spawning runs has become much later, with a spring run now being the norm. As fishery managers, the department seeks to understand why this shift has occurred and also investigate whether it is possible to manipulate the run timing to return to a more traditional winter run, and this is why preparations are being made to release juvenile rainbow trout into the Tongariro system.
As explained in more detail in issue 64 of Target Taupo, we are embarking on a trial release of up to 20,000 juvenile rainbow trout in June 2012. These fish will be either from Lake Otamangakau or Lake Tarawera depending on the findings of a comprehensive genetic study. These juveniles originate from early running adults and so will hopefully breed early in 2-3 years time. Upon release into the Tongariro system, the juvenile rainbows will be of a suitable size to avoid the likelihood of being predated upon by brown trout. They will be tagged so they can be monitored to see if they return as early running adults.
As this is a trial over the next three years, the experiment will be refined, based on our results, to improve the outcomes of the trial.
This will explore the feasibility of restoring the early runs in the Tongariro system, while the fishery at large will still rely upon natural spawning to ensure its future. In the meantime, over the next few months anglers should enjoy some excellent fishing as the Tongariro River brown trout make their way upriver to spawn.
Programme Manager Field Operations – Fishery
Taupo-nui-a-Tia Area Office
Phone: 07 384 7158
Cell: 0272 386 319
Target Taupo, January 2012, issue 64
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