Effectiveness of metal tags,--Metal tags have held up well after eight 
years of use. By recovering marked male seals of the 1942 series (which were 
branded as well as tagged) we have been able to estimate the percentage of 
loss of tags, as follows: 
1943 1944 1945 1946 Total or mean 
Age of seal in years 2 3 4 5 === 
Number of seals recovered 155 177 192 Ava 538 
Percentages (of those 
recovered this year) 
retaining tag 65 89 77 79 78 
(While we recovered tagged seals after 1946, they were selected specimens and 
can not be compared with those taken previously.) 
When metal tags are improperly clinched they are inefficient, Toward 
the end of the 1941 tagging season the plier, or fastening tool, became worn 
with use. Some of the last seals tagged were at Northeast Point, and at this 
rookery four years later we observed that 17 out of 39 branded seals were 
without tags, representing an efficiency of only 44 percent. Taking into 
consideration a number of small factors upon which we shall not dwell here, 
we believe that it is reasonable to expect a tag efficiency of 75 percent 
after five years of service, using one tag, or 94 percent using two tags. 
Relative merits of selected metal tags.--Starting in 1941, metal tags of 
three different sizes have been applied to the flippers of fur seals. These 
tags are modifications of standard ear tags used in the United States on 
sheep, hogs, and cattle. Reviewing, after eight years, the efficiency of 
these tags as used on fur seal pups we conclude that the smallest tag is best 
adapted to short-term studies and the largest to long-term studies, That'is, the 
small tag fastens to the flipper of the infant seal with a minimum of disconm- 
fort and tearing of flesh. It is more apt to stay in place, up to age five 
years, than is the large one. From age five onward, however, when the flipper 
becomes broad and thickened, the large tag is more suitable. The following 
table gives a comparision of sheep-size and hog-sige tags recovered over a six- 
years period: 
19LA 1945 1946 1947 1948 1949 
Age of seal in years 3 4 5 6 7 8 
No. % No. 42 Now 2 Now 2 Now & Now & 




Seals recovered 
with small tags, 
sheep size 82 52 89 60 § 73 9 43 0 0 0 O 
Seals recovered 
with medium tags, 
hog size 76 
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