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Ship Strikes: collisions between whales and vessels

Most reports of collisions between whales and vessels involve large whales, but all species can be affected.  Collisions with large vessels often go unnoticed and unreported. Animals can be injured or killed and vessels can sustain damage.  Serious and even fatal injuries to passengers have occurred involving hydrofoil ferries, whalewatching vessels and recreational craft.

The IWC and ship strikes

Both the Conservation and Scientific Committees of the IWC are working to understand and reduce the threat posed by ship strikes.  A Strategic Plan to Mitigate the Impacts of Ship Strikes has been developed and aims, by 2020, to develop approaches and solutions to  achieve a permanent reduction in ship strikes.  The IWC is also collaborating with other relevant organisations at both regional and inter-governmental levels to share information and expertise.  

Click here to read the IWC Strategic Plan to Mitigate the Impacts of Ship Strikes on Cetacean Populations, 2017-20.

More information on this work can be found here


The Conservation Committee provides a forum for members of the IWC to report and share information on the measures being taken within their own countries to reduce and record incidences of ship strikes.  In addition, the Conservation Committee has established a dedicated Ship Strikes Working Group to develop detailed proposals for mitigation of ship strike events and to co-ordinate work between member governments. This group was founded by the late Commissioner for Belgium, Alexandre de Lichtervelde who died in 2011 and Belgium remains committed to this issue.
In 2016, the IWC submitted a paper summarising the IWC's work on ship strikes to the Maritime Environment Protection Committee of the International Maritime Organisation (IMO).  The paper was widely welcomed by the members of the Committee and you can read it here.

In 2010, the IWC’s Ship Strikes Working Group held a joint workshop with scientists and representatives from ACCOBAMS (the Agreement on the Conservation of Cetaceans of the Black Sea, Mediterranean Sea and contiguous Atlantic Area).  The workshop reviewed the available information on ship strikes including mitigation measures for reducing ship strikes.  The report of the workshop can be downloaded here. It developed a number of important recommendations and these form the basis of the IWC’s workplan to address this important issue. The latest report of the Conservation Committee, which includes its discussions on ship strikes, can be found here.


Quantifying the problem

Every year, the IWC’s Scientific Committee considers methods of estimating the number of whales killed from ship strikes. This is not a simple issue.

You can read more about this work here

Mitigation measures

There is no universal solution to the problem of ship strikes.  Technological, operational and educational solutions are all currently being explored and here you can read a summary of the different types of measure that have been implemented around the world.  For now, the most effective way to reduce collision risk is to keep whales and ships apart, and where this is not possible, for vessels to slow down and keep a look out.  All mitigation work needs to be undertaken in a collaborative way as migratory animals like whales travel across national boundaries.

The IWC is working in conjunction with other organisations such as the International Maritime Organization (IMO) and have produced an information leaflet with further advice to reduce the risk of collision. You can read this advice here.  The leaflet is also available in Arabic, Chinese, French, Russian and Spanish).

Specific information for mariners to help with voyage planning

IWC maintains a list of all the measures that have been put in place globally through IMO or national regulations, to reduce ship strike risks to whales. These include Traffic Separation Schemes, Areas to be Avoided, Recommended Routes, voluntary and mandatory speed restrictions. This list is intended to assist with voyage planning. You can view this list here. Please contact if you are aware of any measures that are not on this list.


More information can be found here


Separating whales from vessels is is not as easy as it sounds for both scientific and logistical reasons, but it has been achieved in some areas. In particular, it relies on good information and predictable patterns of whale (and vessel) distribution as well as a practicable alternative route for shipping.

For example, in the Bay of Fundy off the east coast of Canada, long-term data on North Atlantic whale distribution allowed a small adjustment to the shipping lane, adding minimal passage time to shipping, but achieving a substantial reduction in collision risk. A similar approach has been used for shipping lanes approaching the port of Boston on the east coast of the USA. Considerable progress has also been made in Panama and Spain, for example.

In other areas, there is no practicable alternative route for shipping and other potential solutions need to be considered. There is good evidence that ships travelling at slower speeds pose less of a collision risk and in areas where there is a particular concern, vessels have been requested to slow down. For example, there is an area in approaches to the Strait of Gibraltar that appears particularly important to sperm whales, but would be difficult for vessels to avoid.

Measures to regulate shipping, such as modifying mandatory shipping lanes or establishing areas to be avoided, are decided by the International Maritime Organization. In 2009, the Marine Environment Protection Committee of the IMO accepted a a guidance document on minimizing the risk of ship strikes with cetaceans into its work programme.


Ship strikes are an international problem that requires improved knowledge of the behaviour and movements of cetaceans and vessels, and a much better understanding of the numbers of collisions and the circumstances surrounding them. The IWC is committed to gathering this information in order to prioritise areas and species for targeted mitigation measures. A vital component of this is the IWC ship strikes database.  This is a global database of collisions between vessels and whales, and an online public data entry system for submitting reports.  Ocean users are encouraged to report any collision they are involved in or witness.  Each record can then be verified by scientists and the information is used to build a better understanding of when, where and why collisions occur.  Hot spots can then be identified and prioritised.

If you have information relating to a collision between any type of vessel and a whale, dolphin or porpoise please click here to enter your information.

This will open a form that will guide you through the data entry process. Your information will then be passed to our scientists who may wish to ask additional questions.

To find out more about the database click here

National and Regional Cetacean Stranding Networks

Many countries have regional or national strandings networks that maintain records of all stranded cetaceans and where possible ensure that sufficient data are collected to ascertain cause of death. In recognition that ship strikes are one of the reasons for cetacean strandings, a revised list of cetacean stranding networks is provided here for information. If you see cetaceans on the beach then you are urged to contact your local strandings network.  This global list was last updated in March 2011 and contains networks and contact information. Further additions or amendments should be notified to the Secretariat.