i i heard a story in australia about how a pack of orcas were helping whalers catch other whales by somehow driving them into a bay every now and then. as a reward they crew would afterwards give the tongue of the whale to the orcas. one time though there was a big storm and in their hurry to get home safely the captain decided to leave before giving the tongue to the orcas. that was the end of their deal, after being shown that the humans could not be trusted, the orcas never helped them again.

i dont know if its true, or just a local myth, but its a nice story :P