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PACIFIC SCIENCE, Vol. XIII, July 1959 
missing. Large sharks which could inflict 
wounds of this nature are often seen in and 
around Midway Atoll. While the junior au- 
thor was skin diving in Welles Harbor, Mid- 
way, watching the underwater swimming 
behavior of a seal, a school of 8 or 10 white- 
tipped sharks {Triaenodon obesus) was in the 
immediate vicinity. One of the sharks, about 
4 feet long, and the seal swam within 4 feet 
of each other. Neither, however, showed the 
slightest alarm or concern. 
During late May and June of 1956, Fish 
and Wildlife Service biologists of POFI made 
the following observations: ’’On Southeast 
Island [Pearl and Hermes Reef], a pair of 
adult seals was seen well up from the beach. 
The smaller of the pair was seriously wounded 
on the lower abdomen and right side. . . . On 
Whale Island [French Frigate Shoals], a young 
adult was found dead on the beach, appar- 
ently as a result of shark attacks. Most of the 
flesh was gone from the right side of the head 
and neck and the sides showed slashes typical 
of shark bites. At this island, a school of 20 
to 25 three- to four-foot sharks was seen con- 
tinuously milling about the shallow reef in 
the lee of the island.” (E. C. Jones, FWS, 
in lit.) 
We have not heard of killer whales {Orcimis 
orca) in waters around Midway. 
The monk seal is able to increase and main- 
tain its numbers in the Leeward Islands in 
spite of a low reproductive rate. The fact that 
6 yearlings were marked at Midway and only 
4 pups were born (plus 1 stillborn) there in 
1957 may indicate that survival in the first 
year is unusually high. Nearly one-fifth of the 
fur seal pups born on the Pribilof Islands in 
recent years die before leaving the breeding 
grounds and an additional 50 per cent (ap- 
proximately) die of natural causes before 
reaching their third birthday (Kenyon, Schef- 
fer, and Chapman, 1954). It might be con- 
cluded that monk seals are fairly long lived 
and that mortality from disease and predation 
is relatively low. 
MOVEMENTS 
Marking 
In order to follow the movements of indi- 
vidual seals, and to furnish a reservoir of 
animals of known source and age for future 
study, we tagged as many as possible (57). 
The tags were National Band and Tag Com- 
pany size No. 19 monel metal cattle-ear tags. 
On one side was stamped a number preceded 
by "MS-”; the other side was stamped with 
"NOTIEY/F & W SERVICE/WASHING- 
TON 25 D.C.” The tags were clinched on 
the web of the animal’s hind flipper with 
special pliers designed for the purpose. 
Pups, even weaned ones weighing up to 
160 pounds, were easily tagged as they can be 
captured readily and held by hand. The year- 
lings were netted and firmly tied. In order to 
place tags on adults, the animals were quietly 
approached from the rear while they slept. 
The tag was then attached with a quick firm 
motion of the pliers. The seals always awoke 
with a violent thrashing motion that sent the 
pliers flying, but the tags usually clinched 
properly. 
To facilitate recognition of individual seals 
at Midway, we attached to their tags strips of 
colored polyethylene plastic. We placed red 
strips on pups, yellow on yearlings, and blue 
on older animals. Each plastic strip was dis- 
tinctively shaped (long, medium, or short; 
truncate, diagonal, pointed, or notched). 
Some of these were lost after about 1 month. 
These decorated tags were readily observed 
on sleeping seals. With binoculars, they aided 
identification by number on seals that were 
crawling towards or splashing into the water. 
It is often possible to approach a sleeping 
seal and read its tag number. 
An attempt to mark seals by spraying them 
with quick-drying "Krylon” enamel was un- 
successful. The application of the paint awak- 
ened the seals and they crawled away into the 
water, the sand and water wiping off what 
little paint had got on to them before it dried. 
Fast drying paint (of the type used to mark 
highways) applied generously with a swab 
