top of page

See a BLOW ? Go SLOW! HOW to Avoid Ship STRIKE With Whale?

As magical as an encounter with a whale could be, sometimes the encounter can turn into a drama. Collisions with whales are unexpected and often traumatic experiences for both the animals and the boats.

Marine mammals and collisions

A friend told me about his first encounter with a sperm whale: while he was crossing the Atlantic from Central America to Europe on his 12-meter sailing boat with his girlfriend, they survived a traumatic encounter. 1 day before arriving in the Azores, they suddenly felt a massive shock and they thought that the boat was going to break. The first reaction was incomprehension then, a few seconds later, they saw it... A huge bloody sperm whale was floating next to them.

Luckily for them, the boat was fine but the sperm whale incident was not recorded as it is often the case.

This humpback whale, known as "Slash" has a severed dorsal fin and scars along his back from a boat propeller. (Photo credit: Jared Towers)

A 2018 study by Isabella C. Avila analyzed all collisions in the literature between 1991 and 2016. It appears that 72 species of marine mammals are concerned: The Mediterranean, the Canary Islands, Oman, and the South Pole represent the most dangerous areas for dolphins/whales/seals, mainly because this high biodiversity of fauna coexists with the ever-increasing number of recreational boats, long-distance ships, cargo ships and whale-watching boats.

Baleen whales are vulnerable to collisions with all types of boats across the oceans. In California, for example, collisions are the leading cause of mortality among grey whales, while fin, blue and humpback whales are also victims of collisions and are often undetected by large container ships.

The Mediterranean Sea accounts for 30% of the world's maritime traffic and it is estimated that each year between 8 and 40 whales are killed by collisions. To this end, protection organisations have developed the REPCET system. When a whale is visually detected by the crew, they enter the whale's GPS position into the program and the system sends a signal via satellite to all boats equipped with REPCET to stipulate the presence of the whale.

Collisions in sailing

In the sailing world, collisions are often tragic. As more and more boats become faster and more numerous, the risk of collisions is increasing. During the 2016 IMOCA Ocean Masters Transat from New York to Les Sables d'Olonne, 14 IMOCA 60 took the start. After avoiding the Whale Exclusion Zone, 24 hours later, 8 boats will report 15 collisions with floating objects, 6 boats will return to port and one boat will abandon the race.

When a collision occurs, there is unfortunately little that can be done except perhaps notify the coast guard if the animal is injured and is floating on the surface. There is very little in the collision database, so if this happens to you, you can report the case with the animal's GPS position to the International Whaling Commission. This is important to get an idea of the extent of the accidents and to put protective measures in place.

Here is a 10m video Check up made on a Swan after a whale strike to check that everything is ok on your boat after a collision. In short, check that there is no water ingress and inspect the hull and keel as quickly as possible.

How to avoid a collision

Finally the best way to avoid collisions is to sail during daylight (as whales tends to rest at the surface during the night like it is the case for the blue whales), reduce your speed in areas of high whale frequencies (less than 10 knots) and remain vigilant when large groups of birds gather. If you are on the American side, there is the very good Whale Alert application to prevent collisions, record sightings and warn in case of collision or animal entanglement.

Mitigation measures have been deployed, and new technologies need to be developed. Acoustics and smells are possible leads because whales are sensitive to them. In the Canary Islands, where many collisions are recorded, there is now a forensic protocol to determine whether stranding is due to a collision.

But so far there is no miracle recipe, so if you see a breath, slow down!

What about YOU ? Have you ever witnessed a collision?


References :

Current global risks to marine mammals: Taking stock of the threats. IC Avila & al, 2018, Biological Conservation, 2018-Elsevier

Videos :

What to look after on your boat after a collision with a whale:


bottom of page