The  recent postings about weed in the Tarn have prompted the sort of open debate that I hoped this blog would help to stimulate when I started it 18 months ago.  One of the advantages of electronic communication (one of the few!) is its immediacy and the way in which anyone can share information with a large number of people and invite comment.  I had a phone call from Peter M yesterday which centred on his experience in the past with a weed cutter on the Tarn and I promised to investigate this further.  Hot on the heels of this conversation came the email below from Mike H which adds some really helpful new info to Gavin's advice.  The Horn Wort issue is not one I had considered and clearly caution is essential if we are to avoid making the situation worse.  The idea of camouflaged mooring buoys is an interesting one. Of course, the original buoys were placed to provide suitable anchors for the barley straw sausages we use to treat the occasional algae blooms so mooring buoys could be placed as convenient for fishing.  Again views would be welcome.

Remember that you can always post a comment direct onto the blog by clicking the appropriate button at the bottom of the post.  I can then approve the comment for publication so that everyone can see it.

I'm off now to set up ready for the river fly exercise so more on this tomorrow.  Meanwhile here is Mike's email.
Hi Ian,
 
I've been following your items re the weed with interest. I too have kept carp in their various forms for many years (mainly carassius auratus or "goldfish"), as well as species which require more oxygen: orfe, dace, even perch brown trout in my garden ponds. I've also had quite a bit to do with trying to keep lakes and ponds free from "weed" for angling.
 
I certainly agree with Gavin regarding the identification of the so-called oxygenating plants, or submerged aquatics as they are now called. Myriophyllum spicatum (the long-stemmed plant) is the main culprit regarding making fly fishing awkward on the tarn, but it is generally regarded as beneficial to lakes, or as I read in one of my handbooks "an excellent purifier". It's a rooted perennial and I think that we anglers have exacerbated the problem since we no longer tie the punt up to static buoys. Rather, we drag up masses of myriophyllum on the anchor and then discard it to drift off and repopulate another area! I agree that the buoys were a dreadful eyesore; but I wonder whether a few camouflaged buoys flat with the surface, to moor the punt to, might solve it. We could even have a few month's trialling some flat buoys at the start of a new season. I agree that raking is the best way to remove problem myriophyllum, so long as it's left thinly heaped in the margins for a while, to give the creepy crawlies a chance to return to the water.
 
Ceratophyllum demersum (hornwort) is the plant which is often mistaken for canadian pondweed. I think we should be especially careful when raking this one. One of the tench ponds I used to fish years ago became totally unfishable after a couple of well-meaning committee members attempted to rake out the hornwort from the margins before the season started. All they succeeded in doing was "seed" the whole pond. Again I quote one of my tomes "This plant has whorls of dark green leaves round its stems. A brittle plant, segments will break off easily and root, making it an easy plant to establish." So we should be very, very careful when raking - preferably only rake into the prevailing wind, so that any broken stems are washed in to the bank, rather than away from it!
 
Finally, I'm not so sure about over-stocking increasing the level of nutrients in the water. This certainly happens with stocked garden water features, but that's because these fish are fed!! If anything, adding trout to a water and letting them eat some of the water's other inhabitants before removing the said trout for our tables will result in an overall reduction in tarn nutrients! Okay, if a significant number of stocked trout die of old age in the tarn, then that might counteract it - but I'd also argue that our visiting cormorants and/or herons have an effect too.
 
I'm really sorry that I can't be with you tomorrow, but I'll be there in spirit.
 
Regards,
Mike

I think Mike is right about over stocking.  We have never really over populated this water.  The most likely culprit is the food we used to feed the fish in the old pen when this was in operation.

By the way, the weather is fairly non-descript this morning and perfect for what we have planned.  It's warm, cloudy and very still.

Ian