Natural La Jolla: Acrobatic Pacific White-sided Dolphins move into our area

NATURAL LA JOLLA:

They had long been on my list of marine mammals to see. A few weeks ago, I was able to check Pacific White-sided Dolphins (Lagenorhynchus obliquidens) off that list. Sometimes referred to as Lags because their scientific name is a mouthful and their common name is long, these acrobatic dolphins are fun to watch. They will bow-ride if they are in a playful mood and often they will leap completely out of the water.

I first spotted the dolphins while we were a ways off. I saw splashing, sea gulls circling and flashes of dorsal fins. Once they swam closer, I saw the sharply hooked dorsal fins more clearly. The leading edge of the fin is black, but gives way to gray going back. The thick and prominent dorsal fin is a quick identifier for this species.

Sleek and streamlined; lags just look fast. They work together to feed, corralling small schools of fish into an ever-tighter ball. Then each of them darts through through the school to pick off a target. The day I saw them, there were about ten dolphins working on catching lunch. The fish were trying to hide in floating mats of kelp, but the dolphins were able to figure them out. Seabirds were diving on the fish as well, trying to take a few bites here and there.

Pacific White-sided Dolphins have short, rounded black beaks and lips. Their bellies are pure white. On their backs and sides, streaks of gray, white and black extend over their body to their tail flukes. They grow to about 8 feet in length, and give birth to 3-foot long calves, mainly in the summer.

These beautiful dolphins travel in groups and are seen in southern waters near San Diego during winter months; during the summer they are found further north to Alaska.

— Kelly Stewart is a marine biologist with The Ocean Foundation who writes about the flora and fauna of La Jolla. She may be reached by e-mail: NaturalLaJolla@gmail.com