WHALES WERE A CENTRAL figure in the growth of our economy and ability to be self-sufficient, here, in the early days of the United States, as we began our independence and promoted Manifest Destiny. The dawn of the 20th century saw a full-fledged free-for-all of whale hunting in the Southern Ocean, the objective of which was to boil down these animals to oil for machinery and street lamps. Cessation of large-scale commercial whaling did not occur until the 1980s — about the time that your parents were getting rid of their vinyl records — and, by then, nearly all species of great whale were considered endangered throughout the world’s oceans.

Some, like the North Atlantic Grey Whale were completely extirpated. Others, like the North Atlantic Right Whale, were brought to the brink of extinction (populations are now thought to be ~400 individuals). In the Southern Ocean, the waters surrounding Antarctica, over 2 million whales were killed in the 20th century; over 360,000 were Blue Whales, the largest animal to have ever lived on the planet. Best estimates reveal that this extermination brought the population to 1% of its original size. Over 725,000 Fin Whales, the second largest whale, were taken in the same place and period of time.

Like so many other animals and situations, once humans leave them alone, good things happen. Since the cessation of commercial whaling, several species of whales in the Southern Ocean have increased their numbers. Most notably are the Southern Right and Humpback Whales. Scientifically named for where they were first described and their large (16 foot) flippers that act as underwater wings, Megaptera novaeangliae (the big-winged whale from new England), Humpback Whales are now the most numerous whales found in the waters around Antarctica during summer months. These 45-foot long, medium-sized whales roll, and jump, spin, and splash at the surface more so than any other whale. Thus, they are easy to spot and a pleasure to watch.

While whales are air-breathing mammals, they are adapted for life below the surface and spend more than 90% of their time submerged and out of view. Until recently, we knew very little about the underwater behavior of these animals. Technological advances have allowed researchers and engineers to develop small tags that attach to whales via suction cups and monitor the movements and behaviors of whales at depth. When combined with novel visualization tools to recreate the underwater paths of these whales, we are beginning to see below the surface and actually understand how these denizens of the deep behave and capture prey. In order to sustain their massive size and energetic demands, whales require large amounts of densely aggregated prey. Combining tagging studies with the ability to measure where and how much prey is available for whales, we are beginning to understand exactly what whales need to survive and make feeding profitable.

Why is it important to know how whales feed and how much food they need? The waters around the Antarctic Peninsula (the finger of land directly south of South America) support the most amount of krill of anywhere around the continent and, in turn, host the highest numbers and densities of krill predators. Over the past fifty years this region has warmed at a faster rate than any other on the planet and the amount of ice-covered days during winter months has decreased by up to 80 days. Thus, winters are shorter and less ice cover is forming.

This lack of sea ice has grave consequences for both krill and krill predators. Fewer ice-covered days and a smaller area mean less safe haven and critical habitat for krill to grow. It also means that krill predators, like Humpback Whales, have far more and greater access to prey. For example, adult krill typically migrate inshore into the glorious bays and fiords around the Antarctic Peninsula in fall (April-May). It is likely that this movement is triggered by photoperiod, or day length. In years past, as days got shorter, ice cover would increase. Today, when these krill move inshore they shoal into vast swarms in the bays but are not covered by the protective cover of sea ice. The whales take advantage of this and pack themselves like sardines into these bays and feed gluttonously on the krill. In May in one 8×10 km bay, over 500 whales were counted, hovering above a krill swarm that weighed an estimated 2 million tons!

In the short term, this situation would likely benefit the whales, but would reduce the amount of krill in the region due to pressure from whales and less recruitment of new krill into the population (sea ice is required for the survival of krill in their first year of life). Combined with the lack of sea ice from climate warming and its effects on the recruitment of future generations of krill, the outlook is not so rosy. Other krill predators, for example, are not as mobile and efficient as whales. Penguins and seals that rely on sea ice as a platform to rest and maintain their proximity to krill could eventually come into a situation where their access to prey becomes limited. Species that share a common prey resource have evolved mechanisms to minimize the potential for competition. However, the day may soon come when krill numbers are limited and there is not enough to satisfy the needs of every krill predator. Population growth would come to a halt, individual fitness would decrease, and the number of whales and penguins and seals that could be supported would diminish.

So what do whales signify, in this scenario?

To many, whales reflect a functioning ecosystem; Healthy oceans, productive waters. But in the Antarctic, the greatest wilderness on our planet, whales blanketing the bays and fiords of the Antarctic Peninsula in May, when sea ice should have forced them far away to their migratory paths, may represent something more alarming. Against the specter of commercial exploitation and the pall of current climate warming, it is imperative that we understand the rapid climate changes that are being observed, and how they will affect the relationships between sea ice, krill, whales, and the other predators that call the Antarctic home.

The day that the skies of the Southern Ocean are not enriched by the puffs and spouts of whales will loom dark, as human greed and behavior may have ultimately changed the face of the last great wilderness on our planet.

ARI S. FRIEDLAENDER, PhD is a research scientist at the Duke University Marine Laboratory in Beaufort, North Carolina. Ari received his Bachelor’s degree from Bates College in Maine, his Master’s in Marine Biology from the University of North Carolina at Wilmington, and his PhD in Ecology from Duke University. Ari’s research interests include studying the foraging ecology of marine mammals around the world and linking their behaviors to changes in their environment. Ari has used suction-cup tags extensively, having deployed them on 15 species, and has helped to develop new analytical and visualization tools to better understand the underwater movement and behavioral patterns of marine mammals. Ari is currently involved in research around the world, ranging from studying blue, fin, and beaked whales off the California coast, to pilot whales off the North Carolina and Hawaiian coasts, to studying humpback whales off Cape Cod, California, Alaska, and Antarctica. While his field work occurs near and far, Ari’s true home for research is in Antarctica. Ari has made twenty trips to the Southern Ocean and has provided some of the first data on the distribution and foraging behavior of whales from this region. This is particularly important as parts of the Antarctic are warming faster than any other places on our planet. For Ari, understanding the ecology and behavior of marine mammals will allow us all to develop improved means for conserving and protecting, not only whales, but the ecosystems of which they are an integral part. Ari is also passionate about education beyond the scientific community and he regularly hosts photo shows, speaks at museums and schools, and participates in documentary films from the BBC, National Geographic and MacGillvray-Freeman IMAX films.


return to Issue Thirteen