 Life on Earth is finite, and a delicate balance exists. Man must learn to coexist. From the icy waters of the Arctic they come each fall, swimming southward toward the lagoons of Mexico. Along the California coast they provide one of nature's great spectacles, the annual migration of the California gray whale, the longest known migration of any mammal. Generally they travel so close to shore, and there are so many of them that they are likely to be seen from any coastal vessel or from any headland. Cabrio National Monument on Point Loma in San Diego is one of the best observation points for public viewing. Migrating gray whales provide opportunity to see some of nature's largest creatures in their natural environment, an experience never duplicated by viewing captive animals. The predictable migration of gray whales almost led to their extinction. Once whalers discovered the calving lagoons, the whales were at the mercy of man, even with the primitive ships and equipment of the 1800s. Laguna Ojo de Liébre, the largest calving lagoon of the gray whale, was first whaled in 1857 by Captain Charles Scammon, and today is known to most Americans as Scammon's lagoon. Charles Scammon was unique among whalers. Although as persistent a whaler as any, he was also a naturalist with the curiosity, powers of observation, and ability to record findings that marked the scientist. His book on marine mammals has become a classic in biological literature. He even predicted the possible extinction of whales, a situation that is of much concern today. Of the gray whale, he wrote, ere long it may be questioned whether this mammal will not be numbered among the extinct species of the Pacific. Although on its calving grounds, the gray whale proved to be among the most dangerous to hunt, its numbers were so reduced by the 1890s that the fishery was largely abandoned. Sporadic whaling continued, however, and the population dwindled almost to extinction. Finally, in 1938, with international agreement, commercial exploitation of the gray whale virtually ceased by all nations. The speedy capture ships, huge factory ships, and sophisticated equipment of today could completely destroy the species if unrestricted whaling were ever permitted again. Whales, like other mammals, are warm-blooded, breathe air, bear their young alive, and provide them milk from mammary glands. Over many millions of years, they have evolved into the most unique of all mammals. Through the process of evolution, dating back more than 60 million years, whales now have streamlined bodies for an aquatic existence, nostrils, called blowholes at the top of their heads, horizontal fish-like tails, and most of them, a fish-like dorsal fin. They lack hind limbs, and their front limbs are flippers. The layer of fatty blubber in which they are vested serves both as insulation and as a food reserve. In the larger whales, this layer may exceed a foot in thickness. The gray whale is one of the most distinctive of all whales, and thus one of the easiest to identify. Adults may attain a length of almost 50 feet and a weight of 40 tons. Although large, they are less than half the size of blue whales. They lack a definitive dorsal fin, but have a short ridge and a row of sawtooth knuckles near the tail. The tail flukes are broad, and in adults, usually greater than 10 feet wide. Their skin is usually partly covered with barnacles and sea lice that help give the whales the model gray appearance from which their name is derived. Gray whales are baleen or whalebone whales. Baleen is the special structure of horny plates in their mouths, which enables them to strain their food from water. This feeding mechanism is very different than that of the predatory toothed whales, such as sperm whales, killer whales, and dolphins. Gray whales usually swim in a series of dives at a leisurely pace of 3 to 5 knots. Each dive lasts about 3 to 5 minutes, followed by a surface interval during which whales take 3 to 5 breaths, roughly one breath for each minute of dive. They may exceed 10 knots when pursued. The most outstanding feature in the life history of gray whales is their annual migration. Why do these huge animals travel over 10,000 miles on a round-trip journey, which takes more than half of every year? Part of the answer may lie in their specialized feeding behavior. Although they are baleen whales, they do not feed on free swimming organisms. Instead, they feed largely on bottom-dwelling, shrimp-like animals called amphipods, which are very abundant only in the shallows of Arctic seas. Gray whales spend the 4 to 5 summer months here, gorging on the abundance and building up their reserve of body fat. As the days shorten, the surface begins to freeze, food becomes unavailable, and the grays begin their long journey to Mexican lagoons. The first to arrive off Southern California are usually pregnant females. Their appearance can be expected in November. Gray whales travel singly or in small groups called pods, which usually consist of 2 to 4 individuals, but groups as large as 16 animals have been observed. The migration begins slowly and builds to a peak in late December or January, when 70 to 100 whales may pass a given point during the 10 or 11 daylight hours. Straglers continue to move southward past San Diego through February and into March. The last whales, mostly immature, are still moving southward as the first northward migrants appear off California in late February. Scientists have recorded and identified underwater sounds from gray whales. By listening for these sounds and plotting their location throughout the night, it was possible to follow whale activities and to determine that grays do continue to swim at night, although perhaps a little more slowly than during the day. Why must they travel so far? A look at the geography of the Pacific Coast reveals that the lagoons of Mexico are the nearest large bodies of shallow, warm water that are protected from storms and free from the disturbances of civilization. Gray whales once calved in San Diego Bay, but abandoned it as whaling and other human activities drove them away at the turn of the century. The lagoons of Mexico are now the only major calving areas of the gray whale, and nearly all births take place within them. Most calves are born from December to March. At birth, they are 12 to 17 feet long, well-developed and able to swim almost immediately. But the calm waters of the lagoon may help them survive those first few uncertain hours of their lives when they are becoming oriented to the external environment and beginning to use their swimming muscles. Cavs feed on milk provided by their mothers, which contains over 50% fat. They continue to receive milk throughout the northward migration and on into the Arctic summer when they are weaned about seven months after birth. Initial growth is very rapid. During the first year, they attain 60 to 70% of their adult size. The warm water of the lagoons is probably important to calves at the time of birth since they are thin and subject to heat loss until they develop the fatty blubber layer beneath their skin. Shallow waters of the lagoons may also afford protection to calves from predators such as sharks and killer whales. Cows have been seen lying aground or nearly aground in very shallow water with calves swimming and playing freely around them. The persistent migration of the grays would indicate that these lagoons are vital to calving and thus survival of the species. Recognizing their importance, the Mexican government is taking steps to preserve the lagoons for the future use of these magnificent animals. All gray whales, however, do not necessarily make the long migration to the lagoons. A few have been regularly observed throughout the winters off the British Columbia coast. This suggests that there may be more flexibility in the way of life of the gray whale than previously expected. There have been differing views concerning some aspects of the grays' feeding habits. Under a special permit, whales were taken off Central California during both the northward and southward migration. Studies of their fat reserves suggest that they should have sufficient stored energy to make the entire round trip migration without feeding. However, some activities thought to be feeding have been reported from the lagoons and what is believed to be active feeding has been observed during migration. Knowledge is limited concerning nursing mothers and their nutritional needs. It is possible that they engage in some feeding both along the migration route and in the lagoons. Cows do not mate during the winter they bear their young, but during the following autumn and winter. Although grays may be seen mating in the lagoons, many cows are believed to be pregnant before they arrive. From the same studies which provided information about the whale's nutritional needs, it appears that the gestation period, the time during which the young whale develops inside its mother, is 13 months and that many females are pregnant by early December, considerably before they reach the lagoons. The sex ratio is approximately equal, but since females mate only every other year, there is an excess of males in the mating population. This imbalance helps to explain the mating trios which have been commonly observed. The role of the extra male is still not known. Their large size protects grays from most predators. Killer whales do attack them, but rarely does such a confrontation end in death. Grays recognize the streams of killer whales and attempt to avoid such sounds. The first knowledge of gray whale biology came primarily from the writings of Captain Scammon who made observations of both living and dead animals. Because of their large size and underwater existence, whales are difficult to study. Much of what has been learned since Scammon's Day has been the result of painstaking observations made along the migration route plus extended study in the lagoons. Much valuable information was obtained from the series of whales taken off Central California, including most of what we understand about their migration cycles, feeding behavior, growth, and reproduction. The first attempts to collect and maintain gray whales in captivity were largely unsuccessful. Not until recent years were techniques mastered. In 1971 SeaWorld, an oceanarium in San Diego, sponsored an expedition to capture a gray whale. Modifying techniques developed to catch smaller whales, they netted a newborn female calf. After being transported to San Diego where she was successfully maintained for nearly a year, this young whale, which was named Gigi, became world famous. Gigi contributed greatly to our understanding of the gray whale. At first she was fed an artificial whale milk formula, but soon learned to eat squid. She not only ate well, but surprisingly grew at a normal rate. By watching how Gigi gathered squid from the bottom of the pool, scientists began to understand how gray whales are able to feed on small bottom dwelling organisms, such as the shrimp-like amphipods mentioned earlier, which normally comprised the bulk of their diet. For the first time, scientists had at their disposal a live, healthy, feeding baleen whale in a situation they could easily control for their experiments. Specialists from many fields were able to work with Gigi. Sounds were recorded in a situation where there was no doubt of their source, often the problem in field studies. Data were obtained on respiration and heart function. Blood samples were taken, not only to determine the state of Gigi's health, but also to describe her basic blood characteristics. Techniques for investigating blubber thickness and nutrition were evaluated. In addition, a wealth of information was accumulated on the maintenance of baleen whales in captivity. Of considerable interest was the bond of understanding that grew between Gigi and those who cared for her. The ability to communicate with Gigi and to calm her greatly facilitated her management during experiments. In preparation for Gigi's release, a special backpack was designed. It contained a radio transmitter for tracking and instruments to record and transmit the ocean temperature and the whale's depth. Veterinarians surgically attached the backpack, which was designed to fall off automatically after a given period of time. Gigi was released on March 13, 1972, during the northward migration of the herd. Although she weighed almost seven tons, her release went very smoothly. After her release, she was tracked both visually and by signals from her radio pack. The upper side of her tail was almost white from scarring by a rope at capture, which was a valuable characteristic in making visual identifications. The most northern probable sighting of Gigi was off Monterey on May 5, 1972. A whale matching her description, but not positively identified as Gigi, was observed in the Los Angeles area on March 15, 1973, just over a year after her release. Scientists are now in a position to capture great whales, attach a wide variety of instruments, and then return the whales unharmed to their natural environment. Backpacks can be designed to help solve some of the remaining mysteries in the life of the great whale. Its relationship to its environment and even information about the environment itself. Shore observations will always be important in learning about great whales. It is from the choice viewing areas such as Yankee Point near Monterey and Cabrillo National Monument on Point Loma. The daily counting of passing whales will make it possible to estimate changes in the population. From perhaps fewer than a thousand in the 1930s, the population has reached an estimated 13,000. Anyone interested in great whales can learn to interpret much of their visible behavior once some understanding of their natural history is acquired. They are easily identified by the mottled gray coloration and lack of a normal dorsal fin. The time and circumstances of a sighting also provide a useful clue to the identity of a whale. Gray whales are generally seen moving southerly off Southern California from December through February and northerly from late February through April. During the summer, from June through September, they are seen in the Arctic, Bering, and Chukchi seas. Along the migration route, several different behaviors may be observed. Spy hopping occurs commonly in the lagoons, but its function is unknown. The whales may indeed be spying. Breaching describes the behavior of a whale when it leaps almost clear of the water. The purpose of this activity is also unknown. Rolling and splashing at the surface with no apparent forward progress may indicate mating. This may be observed both in the lagoons and along the migration route. Mothers with calves are seen less often by visitors on shore than expected during the northward migration. Any positive sightings made by laypersons are of interest to scientists and may be reported to the National Marine Fishery Service or the Scripps Institution of Oceanography. Yes, the gray whale is one of nature's great spectacles. And the more we understand about it, the more interesting it becomes. Its preservation will provide enjoyment and benefits to us as well as generations of the future.