WHALES AND SHIP STRIKES
A problem for both whales and vessels
Many species of whales and dolphins may be vulnerable
to collisions with vessels. Most reports of collisions
involve large whales but collisions with smaller species
also occur1.
 Especially with large vessels, collisions
often either go unnoticed or unreported, particularly
for the smaller species. Not only the animals can be
injured or killed; for some incidents there has also
been serious damage to the vessel and serious or even
fatal injuries to passengers have occurred involving
hydrofoil ferries, whalewatching vessels and recreational
craft.
The IWC and ship strikes
The IWC is addressing the problem of ship strikes
through its Scientific and Conservation Committees.
The
Scientific Committee has been considering methods
of estimating the number of whales killed from ship
strikes through the
work of the subcommittee on Bycatch and other human
induced mortality; it is also interested in development
of mitigation measures. In this regard it is also working
in close co-operation with the Scientific Committee
of
ACCOBAMS
(see
SC/60/BC7). Reducing ship strikes is a priority
for the Conservation Committee which has established
a Ship Strike Working Group (see Appendix 5 of
IWC60/Rep5) comprising Argentina, Australia, Belgium
(chair), Brazil, Denmark, France, Germany,
Italy, Luxembourg, New Zealand, Portugal, Republic
of Korea, South Africa, Spain, UK and USA.
Quantifying the problem
Of course, collisions are always a problem for the
individual animal concerned. However, the problem becomes
serious at the population level when the number of deaths
from collisions is so great that it affects the population’s
status. Understanding the severity of the problem means
trying to find good information on the numbers of animals
struck in a population and the total number of animals
in the population. This in turn allows priorities to
be set in terms of developing effective mitigation measures.
Evidence of ship strikes comes from a range of sources:
direct observations from the ship, whale carcasses floating
at sea, or washed up on the beach and examined for evidence
of collision; in some cases whales become lodged on
the bulbous bows of large vessels and frequently the
crew only become aware of this when the ship enters
port. However, for every incident that is observed and
reported there will be many others that are missed.
This makes assessing the conservation implications of
ship strikes very difficult.
For some populations, such as the North Atlantic
right whale whose main habitat is the busy waters off
the east coast of the USA and Canada, the mortality
rate is particularly high2. It is thought that mortality
due to ship strikes may make the difference between
extinction and survival for this species. There are
also concerns about the high collision rates for the
population of fin whales in the Mediterranean3. Reported
numbers will never give accurate estimates of the numbers
of whales involved and so there is a need for estimates
based on an understanding of risk and relating this
to densities of ships and whales.
Mitigation measures
It may sound obvious but the most effective way to
reduce collision risk is to keep whales and ships apart.
This 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.
In other areas, there is no practicable alternative
route for shipping and other solutions need to be considered.
There is good evidence that ships travelling at slower
speeds pose less of a collision risk4. 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 2008, the Marine Environment
Protection Committee of the IMO included the development
of a guidance document on minimizing the risk of ship
strikes with cetaceans into its work programme.
The global database: a
tool for the past, present and future
The IWC has developed a standardized global database
of collisions between vessels and whales. The database
includes information on the whales (e.g., species, size,
observed injuries) and on the vessels. In many cases
there is evidence to suggest a ship strike but often
the cause of death cannot be determined conclusively.
It is important that the database clearly identifies
the level of uncertainty in each case. The objectives
of developing the database are to lead to more accurate
estimates of the incidence of mortality and injuries,
to help detect trends over time, to allow better modelling
of risk factors (e.g., vessel type, speed, size), and
to identify high risk or unsuspected problem areas.
This work follows on from previous global reviews5 but
is also intended to provide an ongoing facility for
collecting new information.
The database design was developed by a Vessel Strike
Data Standardization Group within the Scientific Committee
in 2007 (see
SC/59/BC12 and
SC/60/BC5). Data continue to be gathered and in
April 2008 there were 763 validated records. The
current number of records and other useful live
summary data will appear here in due course. All data entered into the database
is passed to a Ship Strikes Data Review Group of the
Scientific Committee for expert assessment. The review
group can be contacted at
shipstrikes@iwcoffice.org
What can you do to help?
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 the
data review group who may wish to ask additional questions.
References
1 Van Waerebeek, K., Baker, A.N., Félix, F., Gedamke,
J., Iñiguez, M., Sanino, G.P., Secchi, E., Sutaria,
D., van Helden, A. and Wang, Y. 2007. Vessel collisions
with small cetaceans worldwide and with large whales
in the Southern Hemisphere, an initial assessment.
Latin
American Journal of Aquatic Mammals 6(1): 43-69
2 Campbell-Malone et al. 2008. Gross and histologic
evidence of sharp and blunt trauma in North Atlantic
right whales (Eubalaena glacialis) killed by vessels.
Journal of Zoo and Wildlife Medicine 39(1): 37–55
3 Panigada, S., Pesante G., Zanardelli M. et al.
2006 Mediterranean fin whales at risk from fatal ship
strikes. Marine Pollution Bulletin, 52 (10): 1287-1298.
4 Vanderlaan, A. S. M. and C. T. Taggart. 2007. Vessel
collisions with whales: the probability of lethal injury
based on vessel speed. Marine Mammal Science 23:144-156
5 Jensen, A.S. and G.K. Silber. 2003. Large whale
ship strike database. NOAA Technical Memorandum NMFS-OPR-25;
Laist, D.W., A.R. Knowlton, J.G. Mead, A.S. Collet and
M. Podesta. 2001. Collisions between ships and whales.
Marine Mammal Science, 17(1): 35-75.
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