Where do whales get their scars?

Fishing gear (article in French) includes nets, ropes, traps, lines and dredges on which non-target species can sometimes get caught or ensnared. Whales can become entangled in such equipment, which sometimes leaves them scarred for life.

The ropes can get wrapped around the pectoral fins, in the mouth as well as around the head, body and peduncle (base of the caudal fin). Rope stretched across the whale’s skin can lead to wounds such as lacerations, notches and cuts. Such injuries can even result in the complete or partial truncation of the caudal and pectoral fins, or a discolouring of the skin. The tighter the rope and the heavier the gear, the deeper the wound will be. Entangled whales can also lose teeth or baleen if the fishing gear gets wrapped in or around their mouth.

In some species of whales, sparring between bulls in their breeding grounds can lead to scarring. This is due to the limited number of females ready to breed compared to the number of available males. Aggressive behaviour includes collisions, blows to the pectoral and caudal fins, peduncle, head, chin and entire body, and even biting.

Certain killer whale populations sometimes adopt a specialized diet where they show a preference for marine mammals such as large rorquals or sperm whales. In this context, these predators sometimes attack calves near breeding sites, leaving them scarred for life, that is when the attacks are not lethal. Rake marks left by killer whales can be seen on the caudal fin of some individuals. The marks can also be found elsewhere on the body, but are more difficult to see.

This type of scar is characterized by the presence of three or more marks that are parallel and equidistant. In some cases, the attacks are more severe and part of the caudal fin may be lost altogether.

The origins of scars in different species of whales are varied. Evidently, there is nothing that can be done to control intra- and inter-specific incidents, since this is simply Mother Nature at work! On the other hand, solutions do exist to reduce the occurrence of scars caused by human activities. For example, recently developed ropeless fishing gear can help prevent entanglements. Moreover, in order to support efforts to protect the endangered North Atlantic right whale as well as other cetacean species, “whalesafe” fishing gear will be mandatory beginning in 2023. Reducing boat speeds in regions frequented by cetaceans or simply avoiding these regions altogether also reduces the chances of collisions.

It is also possible to act on a smaller scale while still making a significant contribution to marine mammal protection. GREMM offers tools for citizens who wish to take action, in particular the “Navigating Whale Habitat” training, which allows participants to deepen their understanding of whales and the regulations in force to protect them. Awareness and education about whales and their health are powerful strategies for safeguarding their future!