These are wales that were cheeky enough to come close to the islands. So they were herded into a designated killing beach with boats, pulled ashore with ball-ended hooks by their blowholes, stabbed in the spine with a spear to kill them and had their necks sliced to drain the blood.
Later they will be cut up and divided among the population by an ancient, non-commercial system and used as food. People will have to make sure not to eat too much and go to the doctor regularly to check their mercury levels, though. Because the modern world with its gold mining and coal burning has poisoned the ocean.