Our usual summer weather in the mornings is overcast. A gray Sunday morning greeted an enthusiastic group of passengers with what is known as an atmospheric marine layer, a temperature inversion. This occurs along the coast from here to San Francisco and beyond. In the Bay Area, they have a name for it, “Karl, the Fog”.
In just under an hour motoring off of the coast, in 250’ to 500’ of water, Captain John White found us a spread out pod of about 300 Long-beaked common dolphins. A feeding frenzy was on, with plunge-diving pelicans and terns. We saw a lot of shy, low-flying black-vented shearwaters, which have the hunting method known as communal pursuit plunging and pursuit-diving to catch prey. Shearwaters can “fly underwater”, going down quite deep to pursue the forage fish. We were witnessing an “all you can eat, ocean buffet table” with not only the hungry, zig-zagging dolphins but a mixed species feeding flock, including the klepto-parasitic Western and Heermann’s gulls stealing fish by harassing the pelicans, making them regurgitate the fish that are still alive while the pelicans are draining their gular pouches of excess water.
Further offshore in over 1500’ of water, we came across a pod of 600 short-beaked common dolphins with much different behavior—high leaps and breaches—than the long-beaked common dolphins we saw earlier. The forage fish was deeper down, 40’ to 100’ deep on our depth finder, and because of this there were no birds, which mainly take advantage of the food patches near the surface. We covered a lot of ocean and saw more pods of common dolphins in the distance. It is amazing to the feeding frenzy that we saw today. Hope to see you on a future wildlife tour in San Diego waters. -Naturalist Greg McCormack
