Fishery Managament: Water Quality



As the first feature in our new fishery management blog, I would like to introduce myself to fellow anglers and readers. My name is Jamie Roddick, fishery manager at Picks Cottage Fishery Ltd. Since my involvement with the fishery (dating from birth when my father originally operated the complex), I have gained a unique insight into fishery management from a very young age. Many anglers take a great deal of interest in understanding the water which they fish, so I hope this new series will provide some interesting reading and aid your fishing.

This first installment will focus on the cornerstone of effective fishery management – water quality! Speak to anyone who keeps/manages fish and they will tell you straight of the bat that that good fish management is good water management. Water quality is determined with the analysis of several key parameters, for the purpose of this blog I have selected the most relevant; Dissolved Oxygen, pH, Turbidity and Temperature


Dissolved Oxygen

Dissolved Oxygen (DO), is of critical concern to any fishery manager. Unfortuantely, there are many sad cases around the country where DO crashes have led to severe mortalities. Picks Cottage has been fortunate to evade any such issues but it’s something we are always on high alert to. From an anglers point of view, an increased level of DO is beneficial to catch rates as fish become more active and more likely to feed. DO is difficult to determine without the use of professional grade equipment however. As a handy rule of thumb though, the higher the pressure and lower the temperature, the higher the DO is generally (both factors increase the waters ability to hold Oxygen). Low DO is often the result of bacterial respiration (breakdown of organic matter) and the reverse respiration of weed in darkness. These are compex chemical proceses but anglers can still consider their effects. High summer temperatures and still windless days accentuate both processes and reduce DO (and catch rates!).



pH is far more than a distant school time memory, it’s a handy means of determining the acidity/alkakintiy of water. Coarse species such as those found at Picks Cottage fishery are generally quite tolerant to variation in pH. However, extreme values on either side of the pH scale can damage tissue (most notably gills). We generally find our water sits slightly upon the acidic side of the spectrum, possibly due to acidic rainfall from nearby London! We monitor pH on a regular basis as it often fluctuates. My personal preference is to maintain a routine monitoring system to forsee problems before they arise. This allows us to respond to incidents the moment a problem develops, rather than waiting for belly-up bodies!

Water Transparency (Turbidity)

Water colour is a very good indication of water quality. It has always amazed me growing up how the colouration of the water can change over the seasons. Over recent years, we’ve noticed that each lake has its own unique level of transparency. The Bottom S and Middle Doughnut Lakes are often gin clear throughout the Summer. This has led to the stunningly dark appearance of our stock, which we’re well renowned for. The higher stocked Match lake behaves quite differently however. It usually starts a mild tea colour (without the milk!), but once catch rates start to increase we see the fish really stir the clay and the water turns muddy brown. So what difference does the colour of the water make to anglers? Talk to any river angler and they possess a deep appreciation of the variation and effect of colour due to the frequently changing nature of rivers. On a Stillwater, the same principles still apply however. Clear water makes rig concealment top priority, visual impact of your angling must be considered especially with the big S lake carp which are very rig aware. Where the water lacks transparency, on the Match lake for example, perhaps try to stimulate non-visual senses. I’ve always found chopped worm to be a great bait on the Match lake for the Tench. Rather than relying on a fish eyeballing your bait, try ‘boosting’ baits to help fish find your bait. Liquid attraction really boosts catch rates so perhaps try hookbait enhancers or oils.



The scientists amongst you might groan for my classification of water temperature as an aspect of Water Quality, but personally it’s a vitally important parameter. When speaking to anglers, you’ll hear every explanation for a fishless session and often its either been a) too cold or b) too hot! From experience temperature really does play an important role in catch rates. Unlike humans, fish are unable to control body temperature (known as poikilotherms for the nerds amongst you). On the whole, coarse species are fairly resilient to low temperatures. The biggest concern with low temperature is the risk of ice and suffocation if fish cannot reach the surface should DO begin to drop. Generally the short term nature of the British weather ensures ice never hangs around long enough to become a concern. Some anglers like to break the ice should they ever come across it, but it must be appreciated that doing so can potentially super chill the water and become a hazard in itself. An increase in water temperature has two main effects, increased respiration and metabolic activity. Both increase fish activity which in turn leads to the fish in question fueling himself up on the bait of his choice. As many anglers have experienced however, a scorching hot summer day can often result in a blank. Warmer weather will often move fish to the upper layers so its in this situation that I’d suggest zig and surface tactics to be more appropriate. My personal prerderence is to use an ESP Controller with a hook length of approximately 3-4ft with a hair rigged dog biscuit.  But much like humans, the fish appear to enjoy the occasional day off and just enjoy a good sun bathe when things really heat up. Extreme heat can potentially be deadly but species such as Carp are quite content in temperatures approaching 30 degrees. This is why so many monsterous carp can be found in the warmer climates across Europe.

I hope you have enjoyed this first instalment in our new fishery management series. I've tried to cover the most relevant aspects but should you have any further questions please feel free to get in touch and I'll do my best to help! The next instalment will focus on habitats, and their influence on angling. 


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  • Jamie Roddick