Historical clue formulations

• Marine mammal that barks — 2024-03-19
• One of many "residents" of San Francisco's Pier 39 — 2023-08-06
• Aquarium performer — 2018-02-17
• Flippered animal along the Pacific Coast — 2017-08-10
• Marine mammal — 2007-01-07
• Flippered animal of the Pacific — 2003-10-20
• Sighting off the California coast — 1997-05-29
• Pacific Coast critter — 1994-07-30