title: What caused the UK's largest common dolphin (Delphinus delphis) mass stranding event?
abstract: On 9 June 2008, the UK's largest mass stranding event (MSE) of short-beaked common dolphins (Delphinus delphis) occurred in Falmouth Bay, Cornwall. At least 26 dolphins died, and a similar number was refloated/herded back to sea. On necropsy, all dolphins were in good nutritive status with empty stomachs and no evidence of known infectious disease or acute physical injury. Auditory tissues were grossly normal (26/26) but had microscopic haemorrhages (5/5) and mild otitis media (1/5) in the freshest cases. Five lactating adult dolphins, one immature male, and one immature female tested were free of harmful algal toxins and had low chemical pollutant levels. Pathological evidence of mud/seawater inhalation (11/26), local tide cycle, and the relative lack of renal myoglobinuria (26/26) suggested MSE onset on a rising tide between 06:30 and 08∶21 hrs (9 June). Potential causes excluded or considered highly unlikely included infectious disease, gas/fat embolism, boat strike, by-catch, predator attack, foraging unusually close to shore, chemical or algal toxin exposure, abnormal weather/climatic conditions, and high-intensity acoustic inputs from seismic airgun arrays or natural sources (e.g., earthquakes). International naval exercises did occur in close proximity to the MSE with the most intense part of the exercises (including mid-frequency sonars) occurring four days before the MSE and resuming with helicopter exercises on the morning of the MSE. The MSE may therefore have been a "two-stage process" where a group of normally pelagic dolphins entered Falmouth Bay and, after 3-4 days in/around the Bay, a second acoustic/disturbance event occurred causing them to strand en masse. This spatial and temporal association with the MSE, previous associations between naval activities and cetacean MSEs, and an absence of other identifiable factors known to cause cetacean MSEs, indicates naval activity to be the most probable cause of the Falmouth Bay MSE.
authors: Institute of Zoology, Zoological Society of London, Regent's Park, London, United Kingdom. paul.jepson@ioz.ac.uk
authors: Paul D
authors: PD
authors: Jepson
authors: Robert
authors: R
authors: Deaville
authors: Karina
authors: K
authors: Acevedo-Whitehouse
authors: James
authors: J
authors: Barnett
authors: Andrew
authors: A
authors: Brownlow
authors: Robert L
authors: RL
authors: Brownell
authors: Frances C
authors: FC
authors: Clare
authors: Nick
authors: N
authors: Davison
authors: Robin J
authors: RJ
authors: Law
authors: Jan
authors: J
authors: Loveridge
authors: Shaheed K
authors: SK
authors: Macgregor
authors: Steven
authors: S
authors: Morris
authors: Sinéad
authors: S
authors: Murphy
authors: Rod
authors: R
authors: Penrose
authors: Matthew W
authors: MW
authors: Perkins
authors: Eunice
authors: E
authors: Pinn
authors: Henrike
authors: H
authors: Seibel
authors: Ursula
authors: U
authors: Siebert
authors: Eva
authors: E
authors: Sierra
authors: Victor
authors: V
authors: Simpson
authors: Mark L
authors: ML
authors: Tasker
authors: Nick
authors: N
authors: Tregenza
authors: Andrew A
authors: AA
authors: Cunningham
authors: Antonio
authors: A
authors: Fernández
mesh_terms: D000818:Animals; D001344:Autopsy; D061006:Bays; D001522:Behavior, Animal; D002423:Cause of Death; D050696:Common Dolphins; D005260:Female; D005843:Geography; D008297:Male; D012307:Risk Factors; D014116:Toxicology; D006113:United Kingdom
references: Vet Rec. 2009 Oct 10;165(15):441-4
references: 19820259
references: Hum Pathol. 1980 Mar;11(2):123-32
references: 7399504
references: Emerg Infect Dis. 2008 Mar;14(3):471-3
references: 18325265
references: Vet Rec. 2009 Jul 18;165(3):86-9
references: 19617615
references: Nature. 1998 Mar 5;392(6671):29
references: 9510243
references: Vet Microbiol. 2002 Dec 20;90(1-4):563-80
references: 12414172
references: Proc Biol Sci. 1998 Jul 7;265(1402):1167-70
references: 9699310
references: J Chromatogr A. 2009 Feb 27;1216(9):1421-30
references: 19162270
references: J AOAC Int. 2009 Jan-Feb;92(1):190-207
references: 19382578
references: J Comp Pathol. 2001 Feb-Apr;124(2-3):102-14
references: 11222006
references: Environ Toxicol Chem. 2005 Jan;24(1):238-48
references: 15683190
references: J Theor Biol. 2006 Feb 21;238(4):764-70
references: 16083913
references: Vet Rec. 2011 Jul 2;169(1):14
references: 21676987
references: Mar Pollut Bull. 2008 Jul;56(7):1248-57
references: 18534632
references: Vet Rec. 1994 Jan 22;134(4):81-9
references: 8178416
references: J Comp Pathol. 1998 May;118(4):317-27
references: 9651808
references: Vet Rec. 1998 Nov 28;143(22):614-5
references: 9871957
references: Nature. 2003 Oct 9;425(6958):575-6
references: 14534575
references: Proc Biol Sci. 2012 Mar 22;279(1731):1041-50
references: 22189402
references: Vet Rec. 1999 Jan 23;144(4):85-92
references: 10097312
references: Int J Legal Med. 2001;114(4-5):232-6
references: 11355401
references: J Wildl Dis. 2007 Oct;43(4):770-4
references: 17984278
references: Vet Rec. 2008 Feb 9;162(6):184-6
references: 18263919
references: Vet Pathol. 2005 Jul;42(4):446-57
references: 16006604
references: Vet Pathol. 2005 May;42(3):291-305
references: 15872375
references: PLoS One. 2013;8(2):e55553
references: 23460787
references: J Comp Pathol. 2006 Nov;135(4):208-16
references: 17067620
references: Clin Diagn Lab Immunol. 2000 Sep;7(5):835-9
references: 10973465
references: Microbes Infect. 2001 Jul;3(9):729-38
references: 11489421