Back in 2006 Aaron Thode presented some remarkable footage at an Acoustic Society meeting that he and Delphine Mathias caught of a Sperm whale deftly plucking a cod off a camera-rigged long-line. It turns out that this is becoming quite a problem for the cod fishermen, as the Sperm whales are letting their friends in on the gig and fishermen are losing a lot of fish.
Aaron’s presentation was given in pre-OCR newsletter times, but a recent NOAA grant given to the Sitka Sound Science Center to see if they can come up with some solutions to this problem gives us a chance to review the situation.
Sperm whales have the largest and one of the more extravagant acoustical organs on the planet, accounting for the amazing shape and size of their head. It seems that the sounds of the cod boats serve as a “dinner bell” – bringing aggregations of Sperm whales to the dinner table. The also give out a signature “creek” as they pluck the fish, so correlations can be made about quantities of fish taken by how many whales.
It remains to be seen how this will end up. It has all of the earmarks of a potential stale-mate. Attempts to discourage net-predator seals with “Acoustic Harassment Devices” has also resulted in a different “dinner bell” scenario. Given the choice between a good meal and ringing ears, the seals choose the meal. (Given the choice between dancing all night and ringing ears we humans choose dancing.)
Perhaps if there was more cod to go around then the whales and the fishermen could more comfortably fish the same stocks. Maybe the solution lies in promoting more restorative fisheries management practices.