Causes of death in short-beaked common dolphins Delphinus delphis stranded in Cornwall, England (2018-2024), reveal the continued threat of bycatch.

Authors

J E F Barnett, H Chadwick, K Astley, N J Davison, R Deaville, B J Godley, A Hawtrey-Collier, G H Leeming, S K Macgregor, S K John, S E Nelms, S Trew, M E Wessels

Published in

Diseases of aquatic organisms. Volume 167. Pages 1-23. Aug 13, 2026. Epub Aug 13, 2026.

Abstract

The short-beaked common dolphin Delphinus delphis is the most frequently stranded cetacean species around the 700 km coastline of Cornwall, southwest England, with over 100 animals stranding each year. Between January 2018 and December 2024, 867 stranded common dolphins were reported, of which 175 (20%) individuals were necropsied. The most common cause of death was bycatch, accounting for 39% (n = 68; interannual range: 29-44%). Observed pathology and available fishing effort data suggest that smaller vessels engaged in static (and potentially drift net) fishing were the most probable cause of the majority of diagnosed bycatch mortality. Infectious disease was the probable cause of death in 25% of cases (n = 43), with severe parasitism being implicated in 32 of these cases. Live stranding of animals in relatively good health and nutritional status accounted for 10% (n = 17) of cases, where the only significant pathological changes found were lesions that could be attributed to the stranding event itself. Non-bycatch related trauma (n = 14) and starvation (n = 13) represented 8 and 7% of cases, respectively. Other causes of death included gastric impaction (n = 5), peritonitis (n = 3), intestinal impaction (n = 2), non-bycatch related asphyxia (n = 2) and gas embolism (n = 2). In 5 cases, the cause of death could not be established. Necropsies of common dolphins carried out in Cornwall make a substantial contribution to our knowledge of the threats faced by this species in UK waters and the wider region. This includes the continued impact of fisheries-related mortality, with Cornwall being the hotspot for bycatch of this species in the UK.

PMID:
42592779
Bibliographic data and abstract were imported from PubMed on 13 Aug 2026.

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