Lagenorhynchus obliquidens
Pacific white-sided dolphins sweep into SoCal waters from the open North Pacific each winter in herds of hundreds — occasionally topping 2,000 animals — often mixing with common dolphins and riding the bow waves of whale-watching boats in tandem. A bold pale stripe running from eye to tail and chartreuse "suspender" patches on the flanks make them easy to identify even mid-leap.
Survey density inside the Bight fell about thirtyfold between 2004 and 2012, and acoustic monitoring shows a step change after the 2014–16 marine heatwave. But the wider stock of roughly 35,000 shows no long-term trend: these dolphins shifted range out of the Bight rather than declining as a population.
HOW RARITY IS JUDGED →Newport & Long Beach operators share daily trip counts — you can see what was spotted before you book. Other operators don't publish daily reports.