An interesting chart from this paper!

Another fascinating fact from the paper: it appears that the Gulf of Alaska transients do in fact mingle with West Coast transients. They were seen swimming together in Glacier Bay in 2001. It is not yet known if they interbreed.

2

Cruise of the revenue steamer Corwin in Alaska and the N. W. Arctic ocean in 1881 on Flickr.

By United States. Revenue-Cutter Service.
Bean, Tarleton H. (Tarleton Hoffman), 1846-1916 
Muir, John, 1838-1914 
Nelson, Edward William, 1855-1934 
Rosse, Irving C, 1842-1901 
Publication info
Washington,Govt. Print. Off.,1883.
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