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Did You Know?
In Did You Know? the National Geographic magazine team shares extra information we gathered to expand your knowledge of our featured subjects.

Humpbacks' Big Splash

When a 40-ton (36 metric tons), 45-foot-long (14 meters) humpback launches into the air and falls back to sea, the splash is enormous. But humpbacks may make an even bigger splash in late 2007, when the largest, most in-depth and complicated census and study of humpbacks (likely of any whale species) ever attempted will be published.

Dubbed Structure of Populations, Levels of Abundance and Status of Humpback Whales, or SPLASH, the project was spearheaded by the National Oceanic and Atmospheric Administration yet represents unprecedented international partnerships with foundations, agencies, and governments. Since 2004, 300 researchers from ten countries have worked together to photo-identify several thousand humpback whales around the entire North Pacific.

Distinct humpback populations mirror the layout of Earth's oceans: The Atlantic population differs from the North Pacific and the South Pacific population. Another population inhabits what some call the Southern Ocean, around Antarctica. The objective of SPLASH is to determine how many humpbacks live in the North Pacific. Covering the entire North Pacific is no one-person job. While scientists from Russia tracked and studied humpbacks from chilly Kamchatka up to the chillier Bering Sea, Philippine scientists plied the warmer waters of southern Asia. Similar efforts were made by scientists in Canada, the U.S., Mexico, Guatemala, Nicaragua, Costa Rica, Panama, and Japan. No matter where or how the data were obtained, SPLASH researchers had a constant and comparable sampling effort over the entire North Pacific, and across a number of years.

Why the effort? And why now? Population estimates were made in the 1990s, but those held some biases and left much of the North Pacific unsampled. Observation indicates a growing humpback population, with perhaps an annual growth rate of 7 percent, thus the need to pin down those numbers. Such basic information is crucial for researchers endeavoring to understand the effects on the whales of global warming, fishing, toxins, noise pollution, entanglements in fishing gear, and boat strikes. For instance, between 20 to 50 percent of humpbacks bear scars caused by entanglements in ropes and other gear—and those are the lucky ones. In addition to these challenges are the increasing calls from some countries for a resumption of humpback whaling. Without population figures, how can humpbacks be managed at a sustainable level?

Yet SPLASH is not just a counting effort. It delves deeper, identifying and tracking individual whales through photographic techniques and DNA analysis of skin samples. The project shows just how much can be learned from whales without the need to kill them. In 2004 alone, it identified 2,786 whales. Sex ratios, birthrates, and the nuances of subpopulations are all being examined. The project will pinpoint the North Pacific's breeding and feeding areas for humpbacks. Scientists have identified distinct groups of Pacific humpbacks that migrate from different breeding areas near the Equator to higher latitude, colder, productive waters to feed. SPLASH will identify which whales go where, when, in what numbers, and for how long.

The results are highly anticipated and may have far-reaching consequences. Understandably, collating all the data and publishing results takes time, but the SPLASH project aims to publish findings in 2007. The last good estimate put the North Pacific population at around 7,000; SPLASH could put the population at 10,000 to perhaps 25,000. While it may seem the overall population is doing reasonably well, some populations may be in trouble, such as in the western North Pacific, where many humpbacks are caught in nets. Populations are more complicated than at first glance. While high overall population figures could bring calls to remove humpbacks from the endangered species list and to resume whaling, the data on local struggling populations would deflect these suggestions. In any case, SPLASH will create its own splash.

—David A. O'Connor