The Scottish Dee fisheries board recently published the following advice for anglers, this equally applies to the Welsh Dee. When ever possible keep fish in the net and do not remove them from the water. On netting a fish cut the leader and put your rod down (out of harms way) you then have both hands to remove the hook from the fish in the net. If the fish is hooked deeply do not try to remove the hook as this can cause damage, simply cut the leader close to the fish, let it recover and then release it, the hook will eventually fall out on its own.
Salmon mortality from catch and release fishing is low, and this is a valuable tool in salmon management. However, catching a fish has many consequences which can have lethal and sub-lethal effects. The key to minimising these effects is to practice good fish handling measures.
The combination of equipment choice, hooking duration, air exposure, and handling time all result in capture stress. The aim of this guidance is to minimise stress.
The direct consequences of taking a fish from water include:
- Gill collapse – Resulting in less oxygen entering the bloodstream which will ultimately end in suffocation.
- Eye strain – Salmon and trout do not have eyelids and so raising them out of water can damage the eye and is also highly stressful.
- Gravity effects – When out of water, the fish’s body and internal organs are no longer supported. Take care to hold the fish horizontally and support the fish so that it doesn’t damage the spine, bones or internal organs. If the fish kicks out of your hands it may be damaged and will certainly be a stressful experience.
- Skin damage – Damage or scale and mucus loss from nets, dry hands, dropping or placing the fish on the bankside could result in an infection and can stop the fish from reproducing.
- Temperature change – There can be a big difference between water and air/skin temperature and a rapid change temperature will cause stress.
Anglers can have an impact on salmon offspring too, as a fish that exhibits high amounts of stress – from handling and/or temperature – may then produce fewer or smaller offspring or have lower egg survival and disease tolerance.
In short, how a fish is caught and handled has a direct effect on its survival and also the next generation. Minimising stress by following best practice will have a real impact on the number and quality of fish emerging the following spring.
Minimising the time fish are removed from their natural environment must be the goal, and there are numerous studies that suggest air-exposure should ideally be limited to under 10 seconds during the whole catch and release procedure.
- Use barbless, circle hooks and a line weight heavy enough to bring the fish in quickly.
- Minimise time played and bring the fish in quickly.
- Use a suitable, knotless net to avoid skin damage.
- Handle the fish as little as possible and only with wet hands.
- Keep the fish in the water as much as possible – Total air exposure during the whole process should be under 10 seconds.
- Photograph fish in the water or lift just for just a few seconds – holding correctly (below the pectoral fins and on the tail wrist).
- Keep the fish in the water facing upstream to help it recover – don’t pump the fish.
- Allow the fish to recover fully before releasing – the fish should be able to maintain an upright position and respond gently touching at the tail.
- Play the fish unnecessarily.
- Place the fish on the bank.
- Take the fish out of the water longer than completely necessary.
- Lift the fish far from the ground (in case you drop it)
- Treat it rough (bear hug, by the gills, by the tail etc.)
Fishing at 18°C and above
The stress effects from handling can be further compounded with increasing temperature. As water temperature increases so too does the fish’s oxygen demand and energy consumption.
Fishing in water temperatures exceeding around 18°C becomes increasingly stressful to the fish and is linked to decreased immune function and increased susceptibility to fungal infections.
Adult Atlantic salmon have increased risk of mortality at around 20°C. When temperature remains above 20°C for 24 hours fish are unable to repair the damage caused by thermal stress and at this point catching has a noticeable negative impact on survival.
Anglers have a direct impact on whether salmon survive thermal stress. If fishing in warm water (18°C or more), risk of mortality from poor handling is much greater.
- Fishing site is appropriate – aerated riffles, rapids.
- Play the fish firmly and avoid a long fight.
- Fish early in the day.
- Do not lift fish out of water at all – choose fishing site so that this is possible.
Keeping the Dee safe from disease, parasites and non-native invasive species is vital for the wellbeing of the river, the fish populations and other wildlife it supports. One of the key tools with which the Board protects the river and its stock of Atlantic salmon and sea trout is the control and management of Biosecurity.
What is Biosecurity?
Biosecurity is most commonly considered to be a series of measures aimed at preventing the introduction and or spread of animals, plants, pests and diseases and parasites, including non-native species.
Inadvertent introductions of animals, plants, pests and diseases and parasites can go unnoticed until the point that treatment is no longer an option. Therefore, the prevention of introduction is the most effective way to protect our river.
Simple techniques which anyone can employ, such as checking equipment for any plant materials or animals, cleaning or disinfecting equipment and clothing, and simply allowing clothing and equipment to dry out can all be considered biosecurity measures.
What’s at risk?
The River Dee is renowned as being one of the best fishing destinations in the world and we want to protect our river and fish stocks. It is vital that our biosecurity measures are consistent with the rapidly evolving environment within which we live, to reduce the risk to the Dee and its fish stocks.
We need biosecurity to become a routine part of the Dee experience and we need your support to do this. Anglers and ‘other river users’ on the River Dee must consider biosecurity the next time they are using equipment or clothing that has been used elsewhere other than the Dee and not been cleaned, disinfected or dried.