e-Digest Statistics about: Wildlife
Environmental Factors and Pressures
Marine mammal strandings
A pilot scheme to co-ordinate detailed investigations of both pathology and toxicology of strandings of porpoises, dolphins and whales (i.e. cetaceans) around the coasts of England and Wales was initiated in August 1990. This involved collaboration between the Institute of Zoology, SMRU, the Natural History Museum, MAFF's Fisheries Research Laboratory and Veterinary Investigation Service and many other organisations and individuals. The aims were to identify and determine the prevalence of diseases that cause or contribute to mortality in stranded cetaceans and thus provide a means of detecting possible threats to populations. Similar investigations take place in Scotland under a contract placed with the Scottish Agricultural College, Inverness. In England and Wales by the end of 2002, post-mortem examinations had been carried out on 1,100 carcasses of 12 species of cetaceans and cause of death established for 895 of the animals [25].
Table 26 summarises these data by cause of death (see Box 1). These data cover the last four months of 1990, and each of the calendar years 1991 to 2004. Caution should be exercised in extrapolating these data to estimate strandings at total population levels. Post-mortems have been carried out only where logistically possible so these data do not represent a random sample. Also, it is possible that cause of death might influence likelihood of stranding; for example, bycatches may tend to occur nearer the shore than deaths for other reasons and thus be more likely to be stranded.
| Box 1 Causes of death used in Table 26 | |
| Cause of death | Description |
| Bycatch | Represents cetaceans that have died as a result of incidental entrapment in fishing gear. |
| Physical trauma | Covers cases where it was not possible to be certain of the causes of the trauma but an unknown proportion may have been due to bycatch. |
| Live stranding | Means the animal was diagnosed to have died as a result of stranding and showed no evidence of pre-existing serious disease or injury. |
| Not established | Includes cases where it was not possible to establish cause of death, either because no abnormalities were found to which the animal's death could be attributed or because the animal was too badly decomposed. |
The table also includes the numbers of all recorded cetacean strandings on the coast of England and Wales between 1991-2004 regardless of whether a post-mortem was or was not performed. Most of these recorded strandings were reported directly to the Natural History Museum (NHM) via their 24 hour telephone reporting line. However, additional information was provided via the Cornwall Biological Records Unit (for strandings in Cornwall) and Marine Environmental Monitoring (for strandings in Wales). Comprehensive figures for England and Wales are available from 1991, since when a fairly consistent reporting effort across the country has been maintained. Figures for 1990 and earlier years have not been presented as they are subject to under-reporting.
In Detail:
Wildlife monitoring (Environmental Change Network)Further Information:
- Source:
- Institute of Zoology
Data Tables:
| Table
No. |
Title | Download
file type |
| 26 | Stranded Cetaceans by cause of death: 1990-2004, England and Wales |
- References, further reading and links to other resources:
- [24] Fletcher, M.R., Hunter, K., Barnett, E.A. and Sharp E.A., 1999. Pesticide Poisoning of Animals 1998: Investigations of suspected incidents in the United Kingdom. Report of the Environmental Panel of the Advisory Committee on Pesticides, MAFF, London.
- [25] Kirkwood, J.K., Bennett, P.M., Jepson, P.D., Kuiken, T., Simpson, V.R. and Baker, J.R. Entanglement and other causes of death on cetaceans stranded on the coasts of England and Wales. The Veterinary Record.
- Internet Links:
- e-Digest: Coastal and Marine waters
- Institute of Zoology (IoZ)
- Natural History Museum
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Page last modified: 8 December 2005
Page published: 10 September 2003