What a fabulous few years it’s been!

Our Marine Indicator Species project ran over 3 years, from 2023 until 2026. As part of this project, we carried out marine mammal surveys in Cardigan Bay and explored long-term underwater acoustic monitoring. We also delivered community engagement, through community events and opportunities for young people.

The focus of our research

Cardigan Bay is home to a semi-resident population of Bottlenose Dolphins. These are the primary feature for the area’s designation as a Special Area of Conservation (SAC). Previous estimates indicated a notable decline in the number of individuals using the SAC between 2007 and 2016. This result was based on photo-identification data collected between 2014 and 2016.

To better understand these dolphins, we need to investigate the population over the long-term. This means investigating how individuals return to sites they've visited before - called site fidelity. We also need to understand the ecological conditions they require.

Continuing the Visual Record: Boat Surveys

Between 2023 and October 2025, our Cardigan Bay Marine Wildlife Centre team conducted 92 dedicated boat surveys. This included training sessions for volunteers. These surveys took place within the Cardigan Bay SAC. We looked out for not only Bottlenose Dolphins, but also Harbour Porpoises, Common Dolphins, and Atlantic Grey Seals. 

During these surveys, we captured over 40,000 photographs of Bottlenose Dolphin dorsal fins. Scars and other naturally occurring markings make each fin unique, similar to our fingerprints! The unique marks allow us to match them against our historical photo-identification catalogue. Work is currently underway to identify the dolphins we encountered.

Developing a Signature Whistle Catalogue

Bottlenose Dolphins use unique individual vocalisations known as "signature whistles". They use these to broadcast their identity, like how we use our names. As part of this project 1,335 days of our acoustic data was audited. A long process, leading to the creation of the Cardigan Bay Bottlenose Dolphin signature whistle catalogue.

Our findings from this catalogue highlight how differently individual dolphins use the bay. Some dolphins were only detected at one specific monitoring site. Including one individual dolphin which was recorded 136 times at New Quay, and at no other sites! Other dolphins showed much wider movements. The second most frequently detected dolphin was recorded 135 times across three different sites.

Our data has also shown that with acoustic monitoring, we can re-identify the same individuals over decades. In collaboration with colleagues at the University of Bristol results from this important research are currently being prepared for submission to a peer-reviewed journal.

Thank you to everyone who supported this project. Special thanks to our dedicated marine conservation volunteers, our University of Bristol colleagues, and the team from Dolphin Survey Boat Trips.

Our Marine Indicator Species project was supported by the Nature Networks Fund (round two). A programme delivered by the National Lottery Heritage Fund in partnership with Welsh Government and Natural Resources Wales.