Work on the cetacean bycatch mitigation trial (or “pinger trial” for short) began in late 2019, after small-scale Cornish fishermen and the Cornwall Wildlife Trust approached Cefas following incidents of common dolphin and harbour porpoise becoming entangled in gillnets.
As part of Clean Catch, Cefas worked with two skippers to start a trial to test whether LED lights and pingers could be:
During the first stage of the trial, the LED lights were found to be impractical, and these were removed while use of the pingers continued (although lights may be trialled again in the future). In 2022, the trial was paused to enable improvements to its design. As of summer 2024, the trial is up and running again, with a total of nine fishermen now granted licences to take part. We will continue to publish updates about the trial and, in due course, its results.
Find out more about how LED lights and pingers work, and existing research on both devices, on the Bycatch Mitigation Hub.
To fully understand how and why bycatch happens – and ultimately prevent it – we need to know more about the presence and distribution of affected species in and around our waters. For cetaceans such as dolphins and porpoises, this data can be collected using acoustic devices, which passively listen to and record the animals’ echolocating clicks.
In July 2023 in South Cornwall, Cefas deployed seven such devices. Produced by the Cornish-based company Chelonia Ltd, they are known as Porpoise Detectors, or “PODs”. These PODs can identify and classify the echolocating clicks of cetaceans and group them as either dolphins or porpoises based on factors including the duration and frequency of each click, and the time between clicks.
With the help of the Cornwall Inshore Fisheries & Conservation Authority (CIFCA) and local fishermen, Cefas has been servicing the PODs and their moorings in the water and harvesting their data every three months since their deployment. The accumulation of data on echolocation click detections can tell us when and where these animals are likely to be present throughout the day and over the different months and seasons. This important information can then be used alongside fishing data to show when and where these animals are most likely to interact with fishing activity, supporting effective bycatch reduction measures.
Over the last two decades, remote electronic monitoring (REM) technology has emerged as an effective way to gather scientific data from fisheries. These data can include bycatch events and the performance and efficacy of mitigation devices such as pingers, to increase our understanding of why bycatch happens and how to prevent it in future.
In Clean Catch, REM is being used on the vessels of fishermen taking part in the cetacean bycatch mitigation trial (see further above), to support and validate data entered into the self-reporting app by the fishermen and to help develop protocols for bycatch monitoring.
Additionally, in collaboration with the Bycatch Monitoring Project (BMP) and researchers at the Sea Mammal Research Unit (SMRU), video data generated by REM in the cetacean bycatch mitigation trial is being used to build wildlife bycatch image libraries for expert identification of species and to train artificial intelligence (AI) to process REM-generated footage in future.
We are in the process of finding a second fishery operating in English waters to run an additional bycatch monitoring and mitigation trial with. Watch this space for future updates.
Explore the Bycatch Mitigation Hub to find possible measures to reduce bycatch