Newly published research into cetacean strandings around Cornwall shows that entanglement in fishing gear remains the single biggest cause of death among short‑beaked common dolphins found along the county’s shores. The study, conducted by a partnership of local and national groups, examined strandings recorded between 2018 and 2024 and drew attention to bycatch as an ongoing conservation and welfare issue.
Scope of the investigation
The review covered more than 860 short‑beaked common dolphins reported stranded — either dead or alive — on Cornwall’s coastline during the six‑year period. Of those animals, volunteers recovered 175 dolphins for full post‑mortem examination (necropsy). The majority of stranded animals were found dead.
Key causes identified
Among the necropsied animals, the most common cause of death was identified as bycatch, the result of dolphins being entangled in fishing nets or other gear. Bycatch accounted for 39 per cent of diagnosed deaths. Other major causes recorded by the Cornwall Marine Pathology Team (CMPT) and their partners included:
- Infectious disease — 25% of diagnosed deaths
- Live stranding of otherwise healthy animals — 10%
- Non‑bycatch trauma — 8%
- Starvation — 7%
The research was carried out by a partnership that included the Cornwall Marine Pathology Team, Cornwall Wildlife Trust and the University of Exeter, operating under the Defra‑funded Cetacean Strandings Investigation Programme.
What the necropsies revealed
Co‑author James Barnett, affiliated with the CMPT and the University of Exeter, who performed most of the necropsies, said the physical evidence points to particular fishing methods. Marks on many of the bycatch cases indicate entanglement consistent with gill nets and possibly drift nets typically used by smaller fishing vessels.
"Smaller vessels fishing with gill or possibly drift nets are the likely cause of the marks we found on most of the dolphins that died due to bycatch," the co‑author said.
Barnett noted that while diagnosed bycatch fatalities have fallen compared with rates seen 30 years ago, the numbers in this study remain a substantial concern for both conservation and animal welfare. He emphasised the need for improved monitoring across the entire fishing fleet to better understand and address the problem.
Recommended actions and existing measures
The authors and partner organisations pointed to a range of measures with evidence of reducing bycatch. Those measures include:
- Modifying fishing gear and practices
- Using acoustic deterrents such as pingers
- Reducing soak times — the amount of time nets remain in the water
- Closing fisheries in key areas and seasons to protect dolphins
Barnett argued these kinds of steps must be accompanied by an expanded observer programme that covers the full range of vessels, from the smallest boats to industrial fisheries, in order to properly assess the true extent of bycatch. Without such monitoring, efforts to reduce entanglement are limited by gaps in the data.
Role of volunteers and local organisations
The Cornwall Wildlife Trust, which assists in documenting strandings and recovering animals for necropsy, praised the work of the CMPT and the network of local volunteers who responded to incidents around the coast. In a statement the trust highlighted the efforts of the Marine Strandings Network volunteers in retrieving animals for examination and helping to maintain a long‑running dataset.
| Data point | Value |
|---|---|
| Strandings recorded (2018–2024) | 860+ |
| Animals necropsied | 175 |
| Bycatch as cause of death | 39% |
Local wildlife charities say the dataset and the community response are vital to shaping practical mitigation and informing policy. For coastal communities, the findings pose immediate questions about how to balance sustainable fisheries livelihoods with the protection of vulnerable marine species.
The paper stops short of prescribing a single solution, but its authors and partners stress that better fisheries monitoring, practical gear changes and targeted closures offer a route to reducing further loss of life among dolphins that visit or pass along Cornwall’s coastline.
As this work shows, the combination of detailed necropsy data and sustained volunteer effort provides a foundation for policy makers and the fishing sector to act — if they choose to prioritise measures that address bycatch across all scales of the fleet.
