 An older study , examining whales captured by the New Zealand whaling fleet in the Cook Strait region , found a 1 @.@ 69 : 1 ratio of squid to fish by weight . Sperm whales sometimes take sablefish and toothfish from long lines . Long @-@ line fishing operations in the Gulf of Alaska complain that sperm whales take advantage of their fishing operations to eat desirable species straight off the line , sparing the whales the need to hunt . However , the amount of fish taken is very little compared to what the sperm whale needs per day . Video footage has been captured of a large male sperm whale " bouncing " a long line , to gain the fish . Sperm whales are believed to prey on the megamouth shark , a rare and large deep @-@ sea species discovered in the 1970s . In one case , three sperm whales were observed attacking or playing with a megamouth . 
