Adapting to Disability

Since January 2018, no fewer than three grey whales without caudal fins have been sighted along the California coast. One thing is for sure, these animals weren’t attacked by sharks or killer whales! On the contrary, it seems their amputation is due to entanglement in fishing gear. When swimming through rope or nets, whales can end up with material stuck at the base of their tail. Depending on the severity of the entanglement, the rope will gradually cut through the caudal fin or cut off blood circulation until tissue necrosis sets in.

According to marine biologists, the prognosis for a tailless whale is not encouraging. A majority of injured individuals are believed to succumb to the loss of their caudal fin. A disabled whale must overcome many challenges, including less efficient foraging and swimming, which could be particularly troublesome during migration. For a mother with a young calf, the lack of a caudal fin might also mean that she will not be able to defend her offspring against killer whale attacks.

However, some animals manage to overcome these difficulties and adjust to their disability. In 2017, a fin whale with half its tail missing (article in French) visited the St. Lawrence Estuary. In California, the three grey whales overcame the absence of their caudal fins by turning onto their side when breathing and contorting their bodies like a corkscrew to gather enough momentum to dive.

If tailless humpbacks are never reported – despite the species being a frequent victim of fishing gear entanglements – it may simply be because they do not survive long without a caudal fin. Large rorquals have a special feeding technique that requires a powerful tail in order to engulf an enormous amount of water and food. Without it, these whales may be doomed.