The terrestrial mammals in Pacific Rim include black-tail deer, Vancouver Island wolf, black bear, raccoon, cougar, marten, mink, short-tailed weasel, river otter, Norway rat, deer mouse, red squirrel, wandering shrew, Townsend vole and muskrat. Given the relatively small area of the land portion of Pacific Rim, and its linear configuration, the populations of the larger mammals are continuously moving in and out of the park. This mobility makes it very difficult to manage these populations and requires a co-ordinated regional approach with adjacent land management agencies.
Historically, sea otters occurred along the entire north Pacific coast from Japan to the Aleutian Islands and down the west coast of Canada to California. The otter pelt was in high demand by European fur traders in the 1700s and early 1800s, and the animal was virtually extinct by 1830. The Last documented sighting of original sea otters in British Columbia occurred in 1929. Since then, Canadian and American government agencies have successfully reintroduced sea otters, from the remaining Alaskan colonies, to British Columbia in the Checleset Bay area on northern Vancouver Island. The original colony has split into two, both of which are growing at about 12% annually. It would appear that the southern colony is spreading further southward and may eventually recolonize park waters.
The most popular and most frequently sighted mammals in the park are the marine mammals: seals, sea lions and whales. Most exhibit predictable patterns of movement and location, allowing park visitors good opportunities for viewing.
California sea lions, Steller's (Northern) sea lions, and harbour seals are common in park waters. Less frequently seen are Northern fur seals and Northern elephant seals. Sea Lion Rocks, just offshore from Comber's Beach in the Long Beach unit, is one of only 4 year-round haulouts for Steller's sea lions on the west coast of Vancouver Island. It provides visitors with an excellent opportunity to observe sea lions in their natural setting. The Broken Group Islands and the West Coast Trail also have predictable haulout areas for sea lions, although populations at these sites fluctuate seasonally.
Although Gray Whales have been sighted throughout the year, they are most predictably seen during the spring Gray Whale migration as they journey north through park waters. The peak season for watching Gray whales is mid-March to mid-April when the villages of Ucluelet and Tofino welcome visiting whale watchers at their annual Whale Festival. This population of whales has made an impressive comeback from virtual annihilation by commercial whalers during the early 1900s. The hunt was abandoned when the herd became so depleted that pursuit was no longer financially viable. Only a few hundred survived. Since that time, the Pacific herd has increased to more than 20,000 whales, gaining international protection in 1947. These whales represent the only significant population of Gray whales left in the world.
Killer whales are seen throughout park waters, although not as frequently as Gray whales. They are easily identified by their distinctive white and black markings and high dorsal fin. Sleek and awesome, it is the killer whale that most visitors are familiar with and hope to see. Many other species of whales, such as humpbacks and sperm whales, and a variety of porpoise and dolphins, are known to be in or adjacent to park waters.