Alaska Fish & Wildlife News
February 2005

Sea Lion Marks Reveal Birthplace
Nine Rookeries Indicated by Letter

By Riley Woodford

About 3,600 Steller sea lions in Alaska have been marked with a letter and number combination over the past ten years, enabling biologists to identify individual animals. The letter indicates the rookery where the pup was born. For example, F551 is a male sea lion, born in June 1994 and marked as a pup at his birthplace, Forrester Island. He has been seen repeatedly at a haulout on the outer coast of Chichagof Island, and has been sighted as far west as Marmot Island, near Kodiak.

Below is a list of the letter codes identifying sea lions’ birthplaces.

Southeast Alaska (Eastern stock)
F – Forrester Island complex, west of Dall Island, near the U.S.-Canada border
V – Graves Rock, near Cape Spencer
W – White Sisters, near White Sulphur Hot Springs (Chichagof Island)
H – Hazy Island, near the entrance to Chatham Strait

Western Alaska (Western stock)
X – Sugarloaf Island, between Kodiak Island and the Kenai Peninsula
T – Marmot Island, northeast of Kodiak Island
J – Seal Rocks, just outside Prince William Sound
E – Fish Island, just outside Prince William Sound
A – Ugamak Island, in the Eastern Aleutians

= (equal sign) In addition, biologists have captured and released about 375 juvenile sea lions from both the eastern and western stocks to collect genetic and physiological data. Some of these animals have been equipped with tracking and data collection instruments. Because their natal rookeries are unknown, these animals are given a number preceded by an equal sign.

Biologists in the Pacific Northwest are also marking Steller sea lions at several sites along the Oregon and Washington coasts. Russian scientists are marking animals at various sites on the Kamchatka Peninsula and on the Commander Islands, which are between the Western Aleutians and the Kamchatka Peninsula. These are marked with Cyrillic (Russian) letters.

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