MARINE MAMMALS 185 



with little success owing to the number of factors involved. There are 

 changes in factory-ship processing techniques as well as in catchers. Recently 

 the land-based station at Grytviken in South Georgia changed over from 

 using six old and one modern catcher to seven modern catchers, but even 

 here the effect was not clear-cut owing to other variables. 



W. L. N. Tickell: The ratio of propeller to engine speed in some 

 catchers has been found to be critical, as certain ratios cause vibrations 

 which scare whales. Similarly when asdic was first used it was found to 

 scare whales and gunners refused to use it: later, faster diesel-powered 

 catchers returned to asdic as they could outspeed the whales and so hunt 

 them down. 



G. C. Varley: Isn't it this sort of thing that is measured by the catch 

 size? 



W. L. N. Tickell: No, the personal preference of the gunners has been 

 the limiting factor — they would not use the asdic until its success was 

 assured. 



N. Waloff : You said that 600,000 tons of oil was taken — what does 

 this mean in terms of whales ? 



R. M. Laws: This figure is equivalent to about 43,000 blue whales. 

 Current production is in fact about 500,000 tons, and fm whales make up 

 83 per cent of the catch. The whole industry is closely dependant upon 

 economic factors. Oil is the traditional product, and its price has risen from 

 ;{^I2 per ton to £150 per ton between 1912 and 1950. During this period 

 the rising price balanced the rising costs: latterly the price has stabihzed and 

 even fallen shghtly, and it will certainly affect future exploitation. At 

 present the protein in some two milhon tons of meat is not utihzed, the 

 meat merely being processed to extract about 500 tons of oil. This is wasteful 

 and with a rising output of vegetable oils the better use of the meat may 

 become more important. 



W. Edmondson: Has any attempt been made to attract whales by 

 various sounds? 



W. L. N. Tickell: So far as I am aware the only known sounds affecting 

 whales act as deterrents. 



R. M. Laws: One company did try playing krill noises to whales, 

 without success ! 



C. W. Hulme: The International Whaling Commission has been 

 investigating more humane methods of killing whales than the present 

 explosive harpoon. The General Electric Company and a whaling company 

 have been experimenting with an electric system which shows promise. 



