When weed starts seriously doing its thing, fishers and fishery staff alike must get to work. Peter Cockwill assesses the problem and offers some solutions
How fisheries and anglers can deal with weed
IF fishing had its own Room101, weed and mosquitoes would probably be cheek-by-jowl in the ‘IN’ tray. Both are irritating, sneak up on you, are impossible to deal with and apparently serve no useful purpose. If you are a fishery owner then weed is your worst nightmare, because it grows at an alarming rate, and is hugely expensive and time-consuming to deal with; plus its removal is invariably accompanied by a choir of whingeing customers. Should you be a trout, however, then weed is a delight, being home to all manner of critters that you like to eat. It also provides cover from the sun, protection from predators, human and avian, and doubles perfectly as a home and ambush location. Likewise, if you are an aquatic insect, or a baby fish, the weed gives you a home and food, and also life through the oxygen that is produced by photosynthesis. Finding the happy medium between weed’s confounded nuisance value and the boon it represents for a fishery can be challenging. Depending on which side of the counter you stand, there you are in high summer, anticipating either some lucrative footfall or a welcome day’s fishing, only to find that what you thought would be a perfect day is in fact blighted by weed, fouling line and fly alike with every cast and persuading potential customers to stay at home and await better days.
So, what’s the solution?
Well, for the angler, there are quite a few. The first is to check your chosen fishery website for current conditions and back it up with a telephone call or email enquiry. Be patient, though: if it’s a busy time, the owner/manager and staff may well be out on the banks during the day so don’t expect an instant response to all your enquiries. Any fishery worth its salt will be honest about fishing prospects but they also can’t cater for every level of ability. Having checked what the fishery is doing to mitigate the weed problem, you must now accept that you too have to address the situation - it’s no good expecting to fish the place the same way you did when last there, when the water was less cluttered. Be prepared to adapt to the changed circumstances and weeded waters can still be fished successfully. Check the pointers I have provided in the panel accompanying this article.
“If weed were human, it would be tested for steroids: its bulk aside, mare’s tail can easily grow 15cm in a week, ribbon weed double that...”
Now to address the problem from the fishery’s point of view. For starters, it is no longer possible to control aquatic plant life with chemicals. All such options were outlawed from 2010. That leaves the fishery with the possibility of using biological controls, which can be pretty expensive on any lake over a few acres and which call for careful timing. Locking up the nutrient base (phosphates and nitrates) is a developing technique and especially effective with the base algae problems of early season, which give fisheries the dreaded ‘rising scum’.
Anglers will have seen barley straw inhibitors employed as rotting straw in nets, but they can also take the form of a liquid extract, which work better for algal control than plants. Coloured dyes inhibit photosynthesis, and are effective, although the resulting water colour (blue or black) can be off-putting to anglers. They should be reassured that this method works and has no effect on invertebrate life. If you want to keep things ‘organic’, then we reach the elbow-grease option of mechanical control – cutting the weed and removing it. If done with manual chains and scythes, those doing it will need to be fit and strong. It’s far better if the fishery can afford its own weed-cutting boat (or hire one). Some boats have a lifting frame to dump cut weed on the bank, while others just cut it. Whether it’s you or machinery (such as a mini-digger) that eventually gets the weed onto the bank, it will then have to be moved off-site for disposal. You won’t believe how much weed can be harvested from just one acre of water, nor how heavy it is. If weed were human, it would be tested for steroids: aside from its bulk, the likes of mare’s tail can easily grow 15 centimetres in a week, ribbon weed double that, and I sometimes think you only need look at elodea (Canadian pondweed) to trigger a growth spurt. Fishery life can easily lose some of that ‘easy number’ status that it strangely enjoys in the eyes of certain customers, once this fast-growing monster needs reining in, and I’ve mentioned just a few of the many species of aquatic plants that can choke a fishery half to death. Starwort makes dense beds of growth which are really tedious to get out and then there are marginal plants like bulrushes and reeds and all manner of fast-growing water crowfoots (ranunculus). Now add in the filamentous algaes such as ‘cott’, more commonly called blanket weed, or the more simple ‘blue-green’ types which can bloom uncontrollably, and running a fishery begins to feel more like waging a war. Any of these weeds or algae can cause immense deoxygenation at night, when they produce carbon dioxide instead of the ox ygen that they churn out in daytime, and even their demise is no immediate cause for celebration. Following a sudden die-off, the subsequent decomposition of these plants can usher in another oxygen crash. You will often see fisheries running aerators, especially overnight, to try and counterbalance these problems and a humid, thundery night can amount to the perfect storm. In essence, there’s no cure-all for aquatic plants and algae, with every fishery facing its own specific problems, often based on water quality. For example, low pH or acidic waters, with very little in the way of organic nutrients, usually have minimal plant life and rarely get algal blooms or excessive weed growth, whereas waters in fertile farmland, rich in nutrient run-off, can see phenomenal growth rates once temperatures start to climb, transforming fishery conditions from ideal to weedchoked in as little as a week. Then there are the naturally high pH waters, as in the chalk-base regions, which also have ideal conditions for nurturing aquatic plants and which can also see conditions change wholesale in just a matter of days – yes it can happen as quickly as that, then the hard work begins.