Electrofishing is an important technique used by North Wales Rivers Trust to assess fish populations. This technique, which involves using electric currents to temporarily stun fish, allows NWRT to gather valuable data on fish species, numbers, and overall river health. In this blog post, we will explore why electrofishing is conducted, its safety measures for wildlife, and why it remains the current standard for fish population assessment (Dodds & Whiles, 2020).

Why We Do Electrofishing

North Wales Rivers Trust conducts electrofishing to measure abundance of fish populations within a waterbody. This information is essential for effective fishery management, conservation efforts, and habitat restoration. By understanding the distribution of fish species and their populations, NWRT can make informed decisions on how to maintain or improve aquatic environments.

Population Assessment: Electrofishing allows NWRT to estimate fish population sizes, species diversity, and age structures. This data is invaluable for managing fish stocks and ensuring sustainable fishing practices (Lowe et al, 2017).

Habitat Health Monitoring: The technique helps in evaluating the health of aquatic habitats. By examining fish populations and their distribution, NWRT can infer the quality of the habitat and identify areas in need of restoration or protection (Randall et al, 2014).

Species Identification: Electrofishing helps in identifying and monitoring fish species, including those that may be endangered or invasive. This is crucial for maintaining biodiversity and managing ecosystems (Salonen & Taskinen, 2017).

Safety for Wildlife

One of the primary concerns with electrofishing is ensuring the safety and well-being of aquatic life. This was a major consideration in NWRT implementation of electrofishing surveys within our catchment. Here’s how safety is maintained during the process:

1. Non-lethal Technique: The electric current used in electrofishing is carefully controlled to stun fish temporarily without causing long-term harm or death. The fish are returned to the water promptly after being captured (Howell et al, 2022).

2. Regulated Procedures: Electrofishing is conducted under strict guidelines and regulations to minimise stress on fish and other aquatic organisms. The voltage and duration of the electric shock are precisely managed to ensure minimal impact on the ecosystem.

3. Trained Professionals: Only trained and experienced personnel carry out electrofishing to ensure the procedure is performed safely and ethically. This expertise is crucial for protecting wildlife and ensuring accurate data collection.

How It Works

During an electrofishing survey, an electric current is passed through the water using specialised equipment. This current temporarily stuns fish, making them easier to capture and identify. The data collected from these surveys helps researchers understand fish populations and assess the effectiveness of conservation efforts.

Intern Experience

As an intern I have been really excited to get involved with electrofishing with NWRT. The work I have been doing has in large part been aimed at conserving and protecting the fish in rivers across North Wales. It has been nice to survey the fish that have benefited from the work NWRT has done and to see the fish utilising new habitat NWRT have installed and accessing further upstream due to the work NWRT have done to reduce barriers to fish.

References:

Alonso, F. (2001). Efficiency of electrofishing as a sampling method for freshwater crayfish populations in small creeks. limnetica, 20, 59-72.

Dodds, W. K., & Whiles, M. R. (2020). Fish Ecology, Fisheries, and Aquaculture.Chapter 23. Freshwater Ecology (Third Edition), 699-722.

Howell, B. E., Stewart, E. M., Frasca, V. R., Wilson, C. C., & Raby, G. D. (2022). Capture of spawning brook trout by electrofishing does not impair embryo survival. North American Journal of Fisheries Management, 42, 228-235.

Lowe, L., Szemis, J., & Webb, A. (2017). Uncertainty and Environmental Water. Chapter 15. Water for the Environment from Policy and Science to Implementation and Management, 317-722.

Randall, R. G., Cunjak, R., Gibson, J., Reid, S., & Velez-Espino, A. (2014). Using electrofishing data to determine regional benchmarks of habitat productive capacity. Canadian Science Advisory Secretariat.

Salonen, J. K., & Taskinen, J. (2017). Electrofishing as a new method to search for unknown populations of the endangered freshwater pearl mussel Margaritifera margaritifera. Aquatic Conservation: Marine and Freshwater Ecosystems, 27, 115-127.

Written by Jack Johnson