Nearly all of the losses from the hind flipper were of tags fastened 
through the thin black web. Tags clasped over a hind digit were about as 
secure as those fastened to the fore flipper. As we have mentioned (p. 11) 
the tagging of 20,000 pups in 1949 is an experiment designed to test the 
efficiency of hind-flipper tags, 
Accuracy of sex identification in marking operations,=-Wle found that, of 
118 three-year males tagged as pups, only 89 percent had been correctly sexed 
and recorded by the original tagging crew. The sex of a seal pup can be deter- 
mined in a matter of five or ten seconds by examination of the anal region. 
if any importance is attached to the operation it should be done by trained 
and careful observers. 
SUMMARY 
Biologists have marked earless seals (Phocidae) and eared seals (Otariidae) 
for study purposes. Certain useful techniques have been demonstrated, namely: 
branding, tagging, shearing, painting, and punching. Clipping. of ears has not 
been properly tested. Girdling is probably not worth testing, 
1. Hot-iron brands last for life. They have been seen on fur seals 
over 20 years old and on one Weddell seal seven years old. A crew of 25 men 
can brand 1,000-2,000 fur seals in a day, with a mortality of 0,5-0.7 percent. 
On the Pribilof Islands, the best season for branding (and tagging) is Sep- 
tember 1-10. Under no circumstances should the handling of seal pups be pro- 
longed into October, A transverse brand following the fold on the back of the 
seal's neck is preferred to a longitudinal brand. Branding should be used 
only when a permanent mark is required, for example, in determining the life 
span of a pinniped. As compared to tagging, branding is: slower, harder to 
apply, and possibly more painful to the animal. It seriously reduces the 
commercial value of the pelt. It may effect the growth rate of the animal and 
thus detract from its value as a study specimen, although there is no tangible 
evidence of this effect. It does not lend itself to the marking of large 
series of individually numbered specimens. 
2. Metal tags have lasted for eight years on the harp seal (a silver 
tag on the hind flipper) and for at least eight years on the fur seal (corro- 
sion-proof alloys on various parts of the body). Aluminum is too readily 
oxidized by sea-water to be useful, Silver, monel, and stainless steel hold up 
well; monel perhaps the best, 
The ideal tag is thick enough to resist corrosion and abrasion and wide 
enough to be seen at a distance, yet not large enough to injure the flesh or 
to catch on sharp rocks, For fur seal pups, a standard cattle ear-tag has 
proved most useful. (Not, however, fastened to the ear of the seal.) The best 
locations for tags on the fur seal pup are (a) the hind margin of the fore 
flipper at the junction of the furred and the leathery parts, and (b) the hind 
flipper over the first or fifth digit, proximal to the claws. If duplicate 
.tags are applied, the efficiency at the end of five years should be in the 
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