Humpack Whale Breaching By Breakwater

Whales this large usually stay well offshore, so a breach beside a harbor jetty needs explaining. The answer lies underwater. The head of Monterey Canyon, the largest submarine canyon on the west coast of North America, cuts across the continental shelf almost to the surf zone at Moss Landing. Deep water arrives at the shoreline, and with it the currents that gather prey, while coastal upwelling along central California packs krill and anchovy into dense patches in the bay. Humpbacks simply follow the food, which brings them within meters of kayakers.

Getting all the way out of that water is another matter. Biologging work by Paolo Segre and colleagues, published in eLife in 2020, calculated that a single breach by a roughly 15-meter humpback burns about 10.3 megajoules, the most expensive burst maneuver yet measured in any animal and comparable to a person running a marathon. It costs more than a high-speed feeding lunge. A whale that breaches again and again off Moss Landing is paying a steep price for it, and what it gets in return remains an open question.