Earlier this month we received the sad news that a dead sperm whale was found in the Canary Islands, a tragedy that was caused by the whale being hit by a ship.
The young male sperm whale was photographed by Vidal Martín, researcher of SECAC who is one of our North Atlantic sperm whale photo-ID collaborators.
As soon as our biologist Miranda saw the photographs of the deceased whale she recognised him from our photo-ID research. We had not yet named this whale, as he was a fairly new addition to our catalogue, he was simply known as number 356 to us. We encountered him during our tours off São Miguel Island in June 2016, and again in June 2018.
As we reflect on the loss of this sperm whale our attention is drawn to the threat of ship strikes to whales and other marine life.
Maritime traffic is on the increase globally and ships are larger and faster than ever, meaning they sometimes don’t see partially submerged animals and both the boat and the animal often don’t have enough time to react. Whales are very intelligent animals and have a very good sense of hearing, but unfortunately, they often cannot hear large ships until it is too late because the engine noise at the back of the boat is blocked by the bow (this is called the “bow-null effect).
Not many ship strikes with whales have been registered in the Azores, but that does not mean that they do not happen, especially considering the Azores islands are characterized mostly by rocky coastlines rather than shallow slopes with beaches where whales are more likely to be found washed ashore.
It is impossible to know the true size of the death toll, as well as how many non-fatal strikes with whales occur, but it is a potential issue that should for considered for whales in the Azores. The Azores archipelago supports a high density of cetaceans (whales and dolphins), with a total of 28 of the world’s 89 species being registered around the islands (Silva et al., 2014).
So what can we do to assure their safety around boats?
In some areas, local governments are attempting to reduce ship strikes with whales by implementing mandatory ship reporting systems, altering shipping lanes to avoid whale hotspots, deploying acoustic buoys to detect whales from their sounds and detecting whale spouts thermally at night. These technologies and techniques can all help to address the issue, but what seems to be the most effective practice is for boats to simply slow down in important whale areas.
Along the east coast of the U.S. ship strikes with critically endangered right whales declined an estimated 80-90% after a 10 knot speed limit was introduced in two key habitats of the whales (Conn and Silber, 2013). The potential impact of all types of boats should be considered, so of course, that includes our own whale watching boats.
Our passengers often ask us about this during tours, and it is great to see that people are concerned about the welfare of the animals. Azorean legislation states that we cannot go faster than 4 knots or exceed the swimming speed of the animals when we are within 500 m of them. Our boat crew and vigias (land-based lookouts) are always keeping a keen eye out for animals at the surface; and we like to follow the motto – “If you see a blow, go slow”.
Written by Miranda van Der Linde
Conn, P.B. and Silber, G.K. 2013. Vessel speed restrictions reduce risk of collision-related mortality for North Atlantic right whales. Ecosphere 4(4): 1-16.
Silva, M.A., Prieto, R., Cascão, I., Seabra, M.I., Machete, M., Baumgartner, M.F. and Santos, R.S. 2014. Spatial and temporal distribution of cetaceans in the mid-Atlantic waters around the Azores. Marine Biology Research. 10(2): 123–137. ISSN: 17451000. DOI: 10.1080/17451000.2013.793814.