Biodiversity Newsletter Winter 2011 - Merthyr Tydfil County Borough ...

A hundred years of industry saw the decline of the Taff, the last fifty
have seen a dramatic recovery. Long may it continue!
Merthyr’s Recovering Rivers
by Tony Rees, South East Wales Rivers Trust
The Environment Agency Wales has carried out and extensive
programme of monitoring the run of Salmon on the Taff this winter.
The figures show this winter has seen the largest runs of fish since
the Barrage was closed and made into a Fresh Water lake.
The number recorded was 430 salmon. It is possible that there were more than this
entering the river as these are the ones that have been caught in the fish trap at
Radyr weir.
This information is valuable to the Agency and the South East Wales Rivers Trust as
we are working together to improve passage for salmon and trout to help them get
over these obstacles. The Trust looks for low cost solutions to do this work and it has
plans for doing work on the weir at Effi Astex and the one on the Taff Fawr below
Cefn viaduct. We hope to do this work in the summer of 2011
The run of salmon in a river normally takes place on fairly high water, and although
they will rest at the end of a shallow pool when running the river, they need a deep
pool to become resident in when the flood decreases. Although fish have been seen
trying to jump the weir at Merthyr, since the opening of the fish pass this does not
seem to happen. The town weir pool however is not a suitable long term resting
area, so any fish that do not find the pass and go through it will move back
downriver.
All this is far removed from the days when the Taff ran black down the valley due to
the coal mines, and the anglers would not fish below Merthyr due to the pollution.
Things that were once a common sight but seemed to disappear such as the Otter ,
Kingfisher, Dipper, Heron are now making a real comeback and reports are coming
in of otters, kingfishers and dippers being seen regularly along the Taff as far as
Quakers Yard.
The river has however lost, but not completely, an important member of the food
chain: the minnow. This little fish used to be prominent in the upper reaches, but
their numbers have dwindled. At one time there were large shoals of them, and
many of the pools contained so many that it was jokingly said that you would walk on
them if you were in the river. Why have their numbers diminished Could it be the
river engineering works that have taken place over the years have destroyed their
habitat or the very large floods such as those that washed the old bridge to
Abercanaid away
The river is also extremely clean now, as much investment has been put in to reduce
the amount of sewerage that used to find its way into it. It could be that it is too
clean, and the food the minnow used to rely upon is now not there to allow its
numbers to expand again.