Blog

A 2015 UK survey identified the sustainability of target fish species as the top priority for the angling sector. With this in mind, in its first blog, fish21 considers factors contributing to fishery health and fish welfare.

Good water quality is the lifeblood of every fishery and determined by the chemical and physical properties present. Dissolved oxygen, pH, temperature, dissolved solids and turbidity are all important water quality indicators – the relative values of which determine a fishery’s health. Seasonal weather fluctuations, agricultural run-off and the breeding patterns of fish and other fauna (e.g. invertebrates) can all potentially influence water quality.

Nutrients such as nitrogen and phosphorus are essential for plant and animal growth. However, when present in excessive amounts (e.g. agricultural run-off)–  a process known as ‘eutrophication’ – they can promote excessive algae growth. As these algae die and decompose, the decomposing organisms deplete the water of available oxygen. Low oxygen levels can be deadly for fish and invertebrates, a situation compounded when it coincides with higher water temperatures during the summer months.

A serious fish kill can be both upsetting and costly for any fishery owner / manager, potentially jeopardising future business viability, particularly if valuable fish stocks are not insured. Perhaps surprisingly therefore, few fisheries appear to measure even basic water quality parameters, or put in place any checks or controls on what they permit to enter their waterway.

Ideally, baits that supplement a fish’s natural diet and contribute to healthy weight gains will increase the fishery’s asset value, as well as nourishing wider flora and fauna. Dependent on ingredients, fish feeding on highly digestible (ground-) baits can benefit from these as a food source; where nutrient loss to the environment – via undigested feed – is minimised, thereby helping to reduce any eutrophication potential. This will make good business sense both on economic and environmental sustainability grounds.

fish21 provides baseline water quality testing as a standard part of our fishery audit service. In discussion with fishery owners we also aim to build up an understanding of any seasonal / periodic occurrences that negatively impact water quality. Through our Accredited Partners Programme, we can supply all testing and equipment needs. If more in-depth water analysis is necessary, we can take samples and arrange for these to be examined through a UKAS accredited laboratory.

Effective bio-security is also key to fish welfare, where good management represents the best way to minimise associated risks. Diseases can be transmitted through fish-to-fish contact, angling equipment and contaminated water. Stressed fish are typically more susceptible to secondary infections and also have reduced disease resistance. In some instances, angling fisheries may be forced to close until disease problems are rectified, as is the case with koi herpesvirus (KHV) – a highly contagious disease which worst-case may cause up to 100% carp mortality.

fish21’s standard fishery audit includes a review of existing bio-security measures as standard. This enables current systems to be compared with good practice and recommendations made accordingly, including the establishment of an Action Plan where required. We can also source angling equipment to be used by visiting anglers and advise on their ongoing care. A more basic precautionary measure is to provide a dipping tank for anglers to disinfect nets and boots, as well as any equipment that isn’t air dried between use. Many fisheries have now adopted a ‘no dip, no fish‘ rule. The correct use of disinfectants should always be very carefully managed, including their safe handling and storage.

By adopting the above measures, fishery owners can best support healthy ecosystems where fish populations can thrive – and in so doing, protect their most valuable business asset.