WATER QUALITY SEE ALSO ENVIRONMENTAL FACTORS
Appropriate water quality is essential for all life within water holding areas, but what are the important characteristics of good water quality, and how do these characteristics vary for the optimum levels of the different fish species; equally importantly. how do the characteristics vary for the levels of survival and levels of fish development into specimens for those different species Whilst oxygen is an obvious example of an essential characteristic particularly during extreme weather conditions (e. g. very cold periods when a heavily stocked fishery is covered by ice , and and oxygen is unable to reach the lower levels of the water holding area.), but what are the other important but less obvious characteristics .Some anglers also have aquariums or Koi ponds and have the view that the water quality in a fishery should be managed in the same way as that in their ponds, which can be tightly managed and controlled; open waterways, with their inflows and bank erosion continually bringing in elements (e.g. traces of iron, magnesium. calcium sodium, etc) and compounds (e.g. ammonia) which will inevitably have some effects on the water quality, some of which may be good and beneficial whilst others having an adverse effect on the fishery Small unmanaged garden ponds can quickly become no more than water on a bed of sludge with a limited degree of water above the sludge. this may involve complete emptying of the pond. Some However, in reality the larger fishery may hold millions of gallons of water whilst an aquariums or koi ponds will have only a few hundred gallons of water and use systems of filtration which would on major fisheries would be expensive if not impossible to replicate in fisheries. Conversely however , it would take considerable amounts of any element or compound to pollute the fishery. fisheries which may have have millions of gallons of water Management of the water quality is major challenge as effective management involves not only recording the different characteristics but also taking appropriate action to offset any problems. In larger fisheries do what you can with the environment around the fisheries to stop the erosion of water quality (e.g. manage dying tree leaves entering the fishing and increasing the levels of salt caused by the build up of leaf silt at the bed of the fishery; introduce adequate plant life to filter and oxygenate the water and substrate. on larger waters, eg. fisheries silt problems can be a major challenge; mechanical silt removal can help but can also be very expensive, silt reduction compounds are available but can be expensive and unproven. The water can be either aerated only or aerated and also filtered, meaning that a degree of silt, etc. is removed from the water.
I have always been interested to know why for a period of time a certain species in a particular venue reach significant sizes and why they either retain these sizes for many, many years, or alternatively significantly decrease after either short or extended periods, without any fish deaths being seen or reported. . Why for example does a small water of less than 1 or 2 acres support carp over 20lbs. in weight and why do other waters never attain anything like these weights; or similarly why do some waters hold many roach over 2 or 3 lbs. or perch over 3 or 4 lbs, whilst others do not achieve anything like these weights. Adding additional fish stocks to any species will is no doubt be a major factor in this conundrum but there must be many other factors which affect this situation.
To learn more and to assess the levels of consistency on our respective water measurement of important water quality factors were taken on a fortnightly basis for a period of 12 months
There was close similarity on most measurements (e.g. temperature, oxygen levels, very small traces of ammonia and nitrites).
There was, however, an outlier Fir Tree Flash, which had high levels of salinity, conductivity, suspended solids. The Fir Tree Flash had been used as a site for official tipping many years ago.though it continued to produce tench between 3 and 4 lbs, with the odd larger fish, we were unsure as to whether the resident fish had built up resistance to the high salt levels and suspended salts and unsure as to how newly introduced fish would react to these high levels. No significant stocking took place in this water, although limited smaller fish stocking has been used to test the water’s suitability to maintain and improve fish stocks. In the longer term the higher levels do not appear to show any adverse effects on the fishery. The Fir Tree Flash has very good water. The clarity of the water may be important to the angler but it is not always a measure of salinity or conductivity; all the above fisheries vary in clarity at different times of the year or even different times of the month. The quality of Fisheries will never compete with the small ponds used for the development of koi carp and other expensive fish using filtration systems to maintain high levels being tightly controlled. This type of filtration system is replaced by the natural ecological processes in the fisheries, and the water quality will inevitably be of a much lower standard. Aeration is becoming increasingly used in commercial type fisheries to increase oxygen levels and generally improve water quality.
Water is an excellent solvent, it is not surprising, therefore, that water qualities will be very different on different waters. If for example the water is sourced from inflows passing over limestone, then it will probably be much harder and more acidic than inflows from a primarily agricultural setting. If there are no major inflows and outflows the water quality can be influenced/improved by the addition of nutrients which can affect the softness or hardness of the water (e.g. crushed limestone to influence degree of hardness), Care is needed, however, in ensuring the correct levels of nutrients are introduced into any fishery at the right times. Regular checks on the water quality are an essential part of good fishery management. Water quality is particularly important if fish are transferred from one fishery (e.g. fish farm to a fishery). Although approval may be gained for the transfer, the difference between the water quality of the holding area and the fishery to which the fish stocks are being transferred can be critical particularly , if there are major difference in the levels of dissolved oxygen and ammonia. Ideally both waters should be checked for consistency before the transfer. Consider the comparison before transfer. We had one occasion on our waters where a transfer resulted in the loss of a significant number of fish probably as a result of our fishery having significantly lower levels of oxygen and higher levels of ammonia from the farm from which they were transferred
Hardness and softness is measure, if there on a very simple scale of levels of calcium and magnesium mg/l (I.e. mill.igrams per litre) in the water/fishery and is primarily the levels of calcium and magnesium within the water structure. There are no exact value requirements as to how soft or how hard a water body should be in the perfect fishery, but if the levels of calcium and magnesium are sometimes divided into the following ranges. The guide gives some indication of its value of its softness or hardness. The levels will affect the ability of the water to support life.
0 – 75 mg/l SOFT
75-150 mg/l MODERATELY HARD
150-300 mg/l HARD
300+ mg/l VERY HARD
Comparisons of the softness/hardness on your waters together with their respective fishery results can be helpful in managing your respective fisheries.
As well as waters changing their characteristics (e.g. hardness/softness, salts oxygen levels, etc.); changing with the qualities of the inflows that flow into them, the water quality, particularly the levels of oxygen, carbon dioxide, will also be affected by air flows. which are constantly passing from the atmosphere into the fishery. The transfer of oxygen into the water is dictated by the air pressure and temperature, and to a lesser extent by the levels salts within the water. Almost all life aquatic life needs oxygen to survive, only certain bacteria, which use hydrogen and nitrogen as part of what is known as the nitrogen cycle can survive without oxygen. The nitrogen cycle is very important to life within the fisheries. As fish and plant deaths occur, and as uneaten bait and fish faeces build up then so too does the level of ammonia. Ammonia is toxic to fish, even at very small levels. Certain bacteria (Nitrosomanas and Nirobacter), break down the ammonia to nitrites and eventually to nitrates, which are non toxic to fish. There is, however, a limit as to how quickly the bacteria’s can handle the ammonia, so measurement of the levels of ammonia is an important part of fishery management, particularly in heavily stocked fisheries and at times when fish deaths become obvious (e.g. ice covered fisheries)
As mentioned in the section on Environmental Factors the levels of oxygen are critical to all aquatic life, including fish life. The levels of oxygen being dictated being dictated by many many factors (I.e.inflows outflows, air temperature, air pressure, demand from all aquatic life, salt levels, etc..). Plant life is also a factor in the oxygen supply; aquatic plants creating more oxygen during the day by photosynthesis but using oxygen during the night ; this can cause problems early morning in the summer months.
Many clubs and Associations are moving towards the use of aeration to add oxygen to the fishery; some use solar power others electric power. The movement of water does increase the oxygen level, but measure also the effects on conductivity and salt levels to ascertain if they are increased,
Although water depth and aquatic plant life are not directly measurements of the water quality they are major factors in how fisheries can be maintained and developed. Having the right depth to sustain the respective species (e.g. deeper water for bream, shallower areas for spawning of all species) is part of a fishery management plan. The management of weed growth is another important issue that needs constant monitoring; (e.g. having the right balance between protection of the species from bird predation and the needs of the angler is not always easy to achieve). More detail of this type of information is included on the page on Environmental Issues.
Silt levels build up over the years In some cases the silt levels may become a problem; reducing the depth of the fishery and reducing the quality of the fishery. Products are available to reduce silt levels but usually the earlier they applied the better. Monitor the effects of the application on a smaller water or reduced area to assess its effectiveness. Silt levels can be managed either manually, (e.g traps, manual , removal, sluices, etc) though this is a difficult task by the use of chalk, lime, specially supplied chemical agents.
As Water Quality is the major factor in fish health; having the right equipment to measure the quality is essential. Some equipment can be very expensive, others may be no more than test strips (e.g. ammonia, nitrites, nitrates) but may give some indications of problems. Take measurements regularly and record them accurately to identify any problems and trends. See the page on environmental factors as the water environment and water quality are very closely related.