We spend a lot of energy as conservationists protecting marine mammals and ensuring their populations are healthy and maintained. With commercial hunting banned since 1986, many whale populations have stabilised or are recovering in our oceans. However, this news is not welcomed by everyone; fishermen have had a love-hate relationship with marine mammals for centuries. Stories from Greek mythology, Scottish folklore and Roman texts describe the frustration of these intelligent animals taking advantage of easy prey on fishing lines, costing fishermen their sanity as well as their income!
It seems that times have not changed. Since the ban on whaling, sperm whale populations in the Gulf of Alaska are not only recovering, but they are developing sophisticated techniques to outsmart fishermen. They have learnt to determine when cod fishing vessels will be bringing up their catch and they then intercept the fishing lines and literally strip the cod off the lines before the fisherman can land their catch. This behaviour, termed ‘Depredation’ is learned and is being transmitted from individual to individual, with their technique and efficiency improving year on year. 10 so called ‘bad boys’ have been frequently seen, with one individual in particular known to be a pest. His nickname, ‘Jack the Stripper’ gives you an indication as to the frosty reputation he has with fishermen. Costing them hundreds of thousands of dollars in cod, it is no wonder fishermen are keen to find ways to elude these crafty sperm whales. Teams of scientists have been working since 2003 to discover ways to stay one step ahead of the ‘bad boys’ in a project called Southeast Alaska Sperm Whale Avoidance Project (SEASWAP). Whilst there is no denying this must be incredible frustrating and financially crippling, you can’t help but marvel at the sperm whales intelligence and to see the irony of a once heavily exploited animal getting its revenge on its hunter. The hunted has become the hunter!
By Dr Natalie Crawley
Image source: Heather Vukelic