Frequently Asked Questions about Boat traffic

Do whales and dolphins see ships and boats as a threat?

Whales and dolphins live in a world of sound (they find food, communicate, navigate using sound) and, while we don’t know for certain what they make of ships, it is likely that they respond to the sound from the vessel, i.e. they “hear” an oncoming vessel, before they “see” it.

Why do whales and dolphins get struck by vessels?

Sounds obvious, but it is because they spend most of their time under the water. So, they are difficult to spot just below the surface, particularly at night or in rough seas.

Why don’t whales and dolphins get out of the way of an oncoming vessel?

There are multiple reasons as to why animals do not get out of the way of oncoming vessels.

  • They may not see the vessel as a threat, particularly in areas of heavier boat traffic where they are used to the noises around them.
  • They may be involved in activity more important to their survival than moving away from the vessel noise.  For example, when actively focusing on capturing prey or socializing, the drive to engage in those behaviours may be more important to the whale or dolphin than reacting to the noises around them.
  • In some cases, they may not hear the vessel until it’s too late.  Large ships cause something called a ‘bow null’ effect resulting in the engine noise (at the stern or rear of the vessel) being blocked by the bow.  Therefore, it’s very quiet in front of the vessel and the whale would not even hear the vessel until it has passed.

What kinds of vessels hit whales and dolphins?

Any vessels near whales and dolphins are a risk including, jet skis, kayaks, sailing vessels, motor boats and large ships.

What type of injury can ships and boats cause?

Whales and dolphins hit by ships or boats in the water can suffer blunt and sharp trauma.
Sharp trauma results in a cut in the tissue (or flesh) and is usually a result of the propeller striking the individual. Depending on the size of the propeller and speed of the vessel, an injury may occur that results in a series of scars, or even death where main arteries or the spinal cord are cut. 
Blunt trauma occurs when the vessel hull strikes the whale or dolphin . It can injure or kill  but is not always apparent by looking.  Blunt trauma can result in bruising or broken bones that may only be detected through necropsies (an internal post mortem examination).

Where do strikes occur most frequently?

Strikes can occur in any area where whales and dolphins inhabit and where there is a lot of traffic on the water.  The risk is increased in areas where there are lots of whales and dolphins, even if only a few vessels.  The data that is available currently represents the minimum number of collisions that occur as most incidents go unreported, the whales and dolphin body is often lost at sea, and most are not retrieved for the post mortem needed to determine the cause of death.

We know the east coast of the US, waters off California, and the Mediterranean are areas of concern and the seas around Sri Lanka and Hawaii are also problematic. But, this doesn't mean there are not other areas that might even be riskier, there may just be less reporting and documentation coming from them.

Why does it matter if a whale of dolphin is struck?

For small vessels colliding with a large whale, the danger to the vessel and persons on board is high. There are cases of people being injured or killed as a result of being thrown when the ship or boat abruptly stops.  Some collisions have resulted in the vessel sinking.
For large vessels, the whale or dolphin is unlikely to survive the ‘hit’.  For some species, these collisions risk their extinction.  In the case of the endangered North Atlantic right whale, boat and ship strikes account for approximately 50% of the deaths caused by humans, and threatens their survival.

What is the solution?

The only two solutions at the moment are:

  • Separate the ships and boats from the whale and dolphins. In some places, Areas To Be Avoided (ATBAs) have been established, suggesting that ships go around these areas seasonally to avoid whale populations.  Traffic Separation Schemes (TSSs or shipping lanes) have also been moved to reduce the overlap between ships and known whale habitats.
  • Slow down. Research shows that boats and ships that operate at slower speeds (10kts or less) significantly reduce the risk of mortally wounding a whale if it is struck.  Slowing down may also provide the animal with an increased reaction time to move away from the vessel.  Such a speed reduction rule was implemented on the East Coast of the US seasonally to reduce the risk of collisions with endangered North Atlantic right whales.