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Stranded Cetaceans (whales, dolphins and porpoises)

If you see a stranded cetacean please contact your local strandings network

There are reports of cetacean stranding since records began and it is a potential issue for every country with a coastline. Stranding occurs for two reasons – natural processes including age and disease, or human-related issues including bycatch, vessel collisions and environmental degradation. Natural and human-related factors can also interact to cause stranding. Animals may strand alive on the beach, or die at sea and be carried on to land by the currents.

The most obvious and immediate issue is how to deal with live, stranded animals. Successful refloating and release of some smaller cetaceans is possible when conducted by trained responders in the right conditions. Even for dolphins and porpoises however, a stranding is often terminal. Without the support of deeper water, the unnatural weight and pressure on an animal’s organs can cause severe internal injury. The prognosis for larger whales is therefore particularly poor.

Even when terrain and sea conditions seem suitable, refloating an animal that has unseen internal injuries can result in painful and prolonged death at sea. Such attempts can also result in traumatic restranding. Any refloating attempt should be carried out by responders trained and experienced in cetacean health assessment, as even severely compromised cetaceans can look healthy to the untrained eye, and all cetaceans, especially large ones, can be extremely dangerous to handle.

Euthanasia can sometimes be the most humane response, but this is also an extremely challenging task. With small cetaceans, chemical euthanasia is similar to standard veterinary euthanasia of companion animals (cats and dogs) and can be done fairly easily and very humanely. However, with larger cetaceans, the size of the animal necessitates large quantities of euthanasia agent and a large, advanced system of delivery which cannot be deployed safely in surf or with an agitated whale. Countries have developed various techniques, all aiming to achieve rapid death which is as painless as possible, with maximum personnel safety. In 2013, an IWC workshop brought together experts from around the world to share experience and devise best practice protocols for large cetacean euthanasia.

You can read the report of the euthanasia workshop here.

Many countries have regional or national strandings networks which of course, would like every live stranding to result in a healthy animal returned to the sea. For the reasons outlined above, this is often impossible. In these cases, and in cases where animals are found stranded and already dead, the strandings networks conduct post mortems to learn more about the animal and why it stranded to try to assist mitigation measures in the future.

In 2016, an IWC workshop was held to discuss how best to develop practical guidance on handling cetacean strandings.  

You can read a report of the strandings workshop here.

The workshop concluded that an international Strandings Network should be established, involving strandings experts from a number of different countries.  Building on the success of the Entanglement Network, the Strandings Group could  share best practice and produce globally agreed guidelines on strandings response.  The Network could also help to coordinate data from the national strandings networks. The more standardized global data can be collated, the greater our ability to understand the causes of cetacean stranding, and mitigate those causes which are man-made.  These recommendations were adopted by the Commission at its 2016 meeting and work to develop the Strandings Network is ongoing.

To read more about man-made causes of stranding, click here.

Man-made causes of cetacean stranding

There are many potential reasons why cetacean stranding occurs.  It is rarely easy to establish the cause or causes, and often impossible to be definitive.  Some strandings occur through natural processes such as disease, debilitation, or navigational mistakes.  It is clear however that some strandings are caused, directly or indirectly, by the activities of humans.  For example, there may be evidence that a whale was struck by a ship which directly caused injury and then stranding, or evidence that a whale became entangled in fishing gear and drowned shortly before the stranding occurred.  Indirect man-made causes include certain types of (usually) loud manmade sounds which can disorientate cetaceans and ultimately lead them to strand, or habitat degradation which, amongst many possible impacts, can affect health or lead cetaceans away from familiar locations.  In such cases, evidence is scarce and certainty much harder to establish.

 

The IWC runs several programmes to understand and mitigate threats to cetaceans at both an immediate, practical level and through long term collation of standardized, global data.  This information builds a bigger and more detailed picture which increases understanding of the threats and possible mitigating actions.  You can read more about some of these programmes below:

 

Ship strike http://iwc.int/ship-strikes

Entanglement http://iwc.int/entanglement

Anthropogenic sound http://iwc.int/anthropogenic-sound

Habitat degradation http://iwc.int/habitat-degradation

In 2013 the IWC faciliatated the work of an independent panel to examine an unusual mass stranding of melon headed whales. You can read their report here.