 Extensive whaling may have decreased their size , as males were highly sought , primarily after World War II . Today , males do not usually exceed 18 @.@ 3 metres ( 60 ft ) in length or 51 @,@ 000 kilograms ( 50 long tons ; 56 short tons ) in weight . Another view holds that exploitation by overwhaling had virtually no effect on the size of the bull sperm whales , and their size may have actually increased in current times on the basis of density dependent effects . Old males taken at Solander Islands were recorded to be extremely large and unusually rich in blubbers . 
