Juvenile fish monitoring
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ELECTRIC FISHING SURVEYS

Electric fishing is a method used to determine fish populations in rivers and streams and is carried out across the country by organisations such as the Environment Agency and Rivers Trusts. Sites across the Esk catchment have been monitored using this technique over the past 20+ years, as a way of estimating juvenile fish populations, but in the last 5 years a larger number of sites have been surveyed so we can gain a better understanding of fish population changes across the catchment.

In August, 6 keen volunteers joined the Catchment Partnership Officer on a fully certified electric fishing course to enable ‘in house’ monitoring– this newly formed group of electric fishing volunteers is made up of local anglers and River Esk National Park Volunteers all of whom care about the river Esk and want to safeguard the species that live there. Thanks to a grant from the Postcode Local Trust, we have been able to purchase all the necessary equipment required to undertake our own monitoring programme.

During an electric fishing survey, an electrical current is sent through the water which temporarily stuns the fish enabling them to be caught in a net. One team member operates the electric fishing backpack system and two or three team members follow behind with nets and buckets ready to quickly remove the stunned fish from the river. Once caught, the fish are transferred into a large holding tank on the bankside. Each fish is measured using a special measuring board- this enables the relative age of the fish to be estimated. The size and species is noted down and the fish is then released back into the river.

Each site is approximately 50m long, the team start downstream and ‘fish’ up to a natural barrier such as a riffle. Various measurements are taken at each site to calculate the total area fished which then enables the species density to be calculated (no. of fish per 100m2. Health and safety is extremely important when carrying out electric fishing surveys- when carried out correctly this process does not harm the fish and team members can undertake the surveys safely.

14 sites were surveyed in September 2018- species recorded include brown trout (Salmo trutta), Atlantic salmon (Salmo salar), stone loach (Barbatula barbatula), European eel (Anguilla Anguilla), bullhead (Cottus gobio) and brook lamprey (Lampetra planeri). Overall these results showed healthy fish populations at each site, although relatively low numbers of Atlantic salmon were found- a species which is at risk. Electric fishing is a great way of estimating fish populations and this is extremely important on the Esk. Atlantic salmon is a species that is struggling due to a wide variety of issues including water quality and habitat issues, barriers to fish migration and poor survival rates at sea. Monitoring juvenile numbers across the Esk each year will begin to highlight areas where these issues are magnified and can therefore inform the important conservation work that we undertake in the catchment.


First Added: 01/11/2017 16:45:07
Last Edited: 14/11/2018 14:14:58


All Projects > Juvenile fish monitoring

ABOUT THE TRUST

The Esk at Whitby Born out of the River Esk Action Committee, formed to implement the Yorkshire Esk's Salmon Action Plan, the Yorkshire Esk Rivers Trust has... read more

ABOUT THE RIVER

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CATCHMENT BASED APPROACH

Catchment Based Approach Yorkshire Esk Rivers Trust involvement with CaBA - Catchment Based Approach... read more


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