>Feeding sardines were pushing some of the krill into tight balls at the surface, making it easier for hundreds of blue sharks to join in the feast. It was a spectacular event that local photographers and filmmakers would not soon forget. It lent an almost mythical quality to krill — for years, on subsequent trips to the open sea, a few serious photographers would look for a telltale patch of red in the great blue background.
>Krill tend to accumulate in deep canyons, high spots and seamounts, where currents are interrupted and upwelling occurs. At night krill will vertically migrate to shallower surface waters to feed on phytoplankton. Most of the time, however, krill stay beyond human diving depths. Blue whales typically dive to 250 to 600 feet to feed on krill during daylight hours. While working with blue whale researchers, we have watched on the fathometer as blue whales punch though high densities of krill deep below the surface.
>Krill are especially vulnerable to predation when they go to the surface, and the predators often take advantage. It is a wild scene when marine birds, squid and sardines pound the krill. The whales join in with mouths agape, mowing through hundreds of pounds of krill at a time. During these feeding episodes, the krill begin to jump or dance at the surface as whales approach from below, mouths wide open. At the surface, krill can take on various shapes and looks: individual balls or vast mats or layers that stretch for miles. The krill balls take shape as predators attack them, and they act much like baitfish, continually changing shape to confuse the predators or as many individuals keep trying to get to the center for protection. I have seen krill balls appear like red tornadoes at the surface, spinning wildly and changing shape while small fish and squid attack.
>A single blue whale may lazily circle a large krill ball on the surface and make multiple passes to feed. When many whales are present and the competition is high, the aggressive attacks on the krill increase. Mouths come out of the water, and whales cut off other whales to get to the food. Multiple species occasionally join the fray. Humpbacks and blue whales feeding together is not that uncommon off the Northern California coast, and I have photographed blue and fin whales feeding on krill together off Southern California. All three species can occasionally be seen feeding at the same time.
>I have had some unique opportunities to see krill events in the wild. While working on five blue whale shoots for production companies, I have been lucky to witness some great predation situations. The one I remember most clearly was a single minke whale that would go from krill ball to krill ball to eat the sardines feeding on the krill. In 100-foot visibility I could see the event perfectly. The whale stayed about 20 feet away from me and out of good camera range. I couldn't capture it like I really wanted, but that scene is one that I will never forget. Another unforgettable event was watching from our small boat as a group of large Humboldt squid enthusiastically fed on krill with their arms completely out of the water. The krill were so dense at the surface that the squid could use their arms to shovel the krill into their mouths.
>Locating krill on the surface is not something that can be planned, predicted or targeted. Protecting krill populations will promote not only the survival of a huge variety of marine life but also preserve krill sightings — one of the ocean realm's great natural events.
>Watch these videos to learn more about krill.
>© Alert Diver — Q1 Winter 2019