Fishing News index> October 2008

Branch Hydro Scheme Research

Ever since construction of the Branch Hydro Scheme, the Branch Weir and downstream flows have been of concern to Fish and Game in relation to fish passage issues. As part of TrustPowers operating consent conditions, during the past three years TrustPower have been required to undertake timed flow releases in an attempt to improve fish passage to and through the fish pass.  Unfortunately however a video recorder used to monitor success of trout using the fish pass proved to be inconclusive for a number of reasons.

In an attempt to better understand trout movement in the catchment a number of trout will be tagged this year using Passive Integrative Transponder (PIT) tags, with recording aerials to be constructed and maintained at the Branch weir, the fish pass and the intake.  The 23 mm PIT tags will be implanted under the skin adjacent to the dorsal fin, with the tags having an unlimited lifespan.  Several will also be fitted with a radio tags – these will be surgically implanted in the gut cavity, with an aerial protruding near the anal vent.  The radio tags however only last for approximately 12 months.

All fish tagged will be fin clipped. As the programme is to continue for three years, the markings will vary depending on the year and may include clipping of the adipose, left/right pectoral, and/or left/right pelvic fins. In addition all fish will be floy tagged, which is an external tag.  This will be located adjacent to the dorsal fin and will vary in colour depending on year and are individually numbered.
 
Anglers are asked keep an eye out for tagged fish and release them unharmed once they have noted the fin clip markings and recorded tag/aerial colour markings (refer to diagram).  If anyone does decided to keep any of the tagged trout, the internal tag must be removed if the trout is intended for human consumption.

While Ryder Consulting is undertaking most of the work on behalf of TrustPower, Fish and Game and possibly Jacob Lucas, an Otago Masters Student are also likely to be doing some additional monitoring.  Anglers are asked to return any tags/tag details to Fish and Game.

While some anglers may disapprove of fin clipping/tagging, it is hoped that once and for all we will be able to determine the effect of the Branch Hydro Scheme on fish movement and therefore enable improved long-term management of the fishery. 

WARNING

The internal tag (magnified above, length 23mm) must be removed if the trout is intended for human consumption.

Please return any tags removed to Fish and Game

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