283 



Now, the number that you quoted or mentioned, I think 992,000 in 

 1956 down to some other number, and I have forgotten the year you 

 have used, we have found since then that the 992,000 was an exaggera- 

 tion of the true facts. 



Mr. DiNGELL. Are you saying at that point there was an overestima- 

 tion of the population ? 



Dr. Harry. Yes; this was an overestimation and the true value is 

 close to 560,000. 



Mr. DiNGELL. Let me stop you at that particular point. How can 

 you make a mistake ? You are overestimating the population by a mag- 

 nitude of almost two. 



Dr. Harry. That is right, and the reason was that it was deter- 

 mined that the method of marking the animals by tagging with a clip 

 on the flipper was causing an additional mortality. Because of the way 

 the population dynamics works out, you do not ^et as many tags back 

 and because of that, you get an inflated population estimate. As soon 

 as the scientists became aware of this, they immediately began to de- 

 velop a difi^erent method. 



Mr. DiNGELL. When did this happen, what year did this happen ? 



Dr. Harry. What year ? 



Mr. DiNGELL. "WHiat year did this reassessment of the population of 

 the seals take place ? 



Dr. IL\RRY. This was about 1960 or 1961. 



Mr. DiNGELL. 1961 ? 



Dr. Harry. 1960 or 1961 when the scientists first realized that the 

 estimates were too high and began to develop other methods of esti- 

 mating the number of pups. 



Mr. DiNGELL. You are telling us about 1961 they came to the con- 

 clusion that you were having an overlarge estimate of birtlis. 



Dr. Harry. That the estimates were too large. 



Mr. DiNGELL. And I note in 1961 you were killing 43,760 seals and 

 in 1962, the year after you came to this conclusion that you were not 

 having as many births by a magnitude of two, you killed 43,952 

 females. 



It looks to me like you adjusted for your error by increasing the 

 number of females killed by about 200. 



Dr. Harry. I said the scientists first began to be aware of this about 

 1961, and it took some time to develop a new method and check to see 

 whether it was correct or incorrect. 



A new method is being used now, a difi^erent method, and this cor- 

 rects for these errors. 



Instead of tagging with the associated mortality, we are continuing 

 to tag at some times, in some years, but in most years instead of tag- 

 ging and waiting for recoveries 3 or 4 years later, and this is what the 

 problem was, we are now shearing the tops of the heads of the fur 

 seals, and then making population estimates immediately during 

 the year of marking, thus avoiding the mortality factor I previously 

 mentioned. 



This is how it was determined after 1961 that, indeed, these esti- 

 mates were too high, were inflated estimates. 



Mr. DiNGELL. Well, even after that when you found that you had 

 half as many pups as you thought the following year, and I assume 

 this represents the time which you completed some adjustments in 

 your figures, you were still taking 16,000 females. 



