White sharks invoke extremes in our emotions. They bring out a deep, primal fear in some, while others experience joy observing their power and beauty. They are big with a mouthful of serrated teeth. Yet, those who have observed this top end predator from the safety of a shark cage talk about the fluidity and gracefulness of their movements, and their intelligence. While divers can view white sharks in numerous locations worldwide, Isla de Guadalupe has become recognized as the best place to observe and photograph these fascinating animals.

Isla de Guadalupe is located off Mexico, approximately 250 miles south of San Diego and 150 miles offshore of Baja California. This volcanic island is covered with towering cliffs, cinder cones, and plugs. The color in the cliffs defies words. Adentro Island, a rock at the extreme southern tip of the island, glows orange in the morning sun, and the cliffs above Spanish Bay show off colorful strata from thousands of years of lave flows. The island vegetation is rather sparse due to centuries of foraging by wild goats, but the natural flora is slowly coming back; the goats have been eliminated. Offshore the waters are teeming with trophy-sized jacks, tuna and green sea turtles. Guadalupe fur seals, California sea lions, elephant seals, and lobster also live nearby. The only human inhabitants of Guadalupe are a small contingent of Mexican sailors, and a handful of subsistence fishermen.

Guadalupe in unique among white shark diving destinations, and has all a shark diver could ever ask for. First, Guadalupe is home to lots of sharks; you can expect to see 5 to 10 different animals on a 3-day visit to the island. Second, the water is very clear here; often you can clearly see the anchor line from the cage, some 115 feet away! Finally, the water is warm, averaging around 72°F. The sharks are unafraid and hang out near the cages for extended periods of time.

The white shark is the largest of the toothed sharks. They can grow up to 21 feet long and weigh 5000 pounds. They have a mouthful of razor-sharp teeth that can quickly render their prey into bite-sized pieces. We also know that white sharks give birth to live pups as long as 4.5 feet, although no one has ever observed a great white giving birth. A male white shark reaches sexual maturity at 9-10 years old; females take a bit longer and must be 14 to 15 years old to reproduce. The age of most sharks at Guadalupe is in this range and they average about 14 feet long.

White sharks are what I call "warmer blooded" animals. Instead of maintaining their body at a constant temperature like mammals, their metabolism keeps them about 23° F above sea temperature. This feature allows them more energy for bursts of speed, but increases their food requirements. White sharks need calories, and fat is the most compact source of energy. White sharks seek out fatty prey. Young white sharks feed mostly on other sharks and rays and are believed to switch to marine mammals as they grow. They are known to hunt otters, harbor seals, sea lions, and feed on whale carrion. Year-old elephant seals may be a near ideal food for adult white sharks: they are the right size to be subdued by a moderate-sized shark; they have lots of fat, and are relatively unobservant. While at Guadalupe the sharks feed on tuna in the early season and then elephant seals as winter approaches. White sharks but are most abundant at Guadalupe from August through December.

There are few words to adequately describing emotions during your first glimpse of a white shark. First, you notice a barely discernable speck in the distance that slowly assumes a shark-like appearance. Then you notice the length, perhaps as little as 9 feet, but sometimes over 16. Then you are impressed by the girth and then you focus in on the mouth and teeth. They are always impressive.

Some sharks are very shy and cautious, and spend much of their time hanging out below or behind the cage. Others are more confident and will take hang baits 5 to 10 feet from the cage. Others are absolutely fearless and slowly swim inches from the cage, eyeing the divers within. They also have personalized hunting styles. Some will slowly and cautiously approach the hang baits; others will lurk in the depths, and charge the bait from below with great speed and violence. The sharks divers observe from cages are neither excited nor frenzied, and the notion of a shark as a crazed killer is quickly dispelled when you observe them from the safety of a cage. Curious, inquisitive, and graceful are perhaps the most accurate description of these sharks. Each shark also has its own unique appearance. Some are sleek and clean with a flawless complexion. Others are scared by time and violent encounters with prey and other sharks. Adult female sharks usually have bite marks right behind the head, since during mating males hold on to females with their teeth. Many of the male sharks have nasty bite marks around the head, back and gills, presumably by other white sharks. Sharks of both sexes can have paired puncture or cut marks around their mouth, characteristic of elephant seal bites.

Sharks have an image problem. On one hand those who do not know them very well think of them is indiscriminate, savage killers; while those who have spent time with them in the water think of them quite differently. Silent, curious, graceful, sleek.... The words used are descriptive of their beauty not our fear of them. Fact is sharks are one of the most fascinating subjects a diver will ever encounter.

We know surprising little about white shark biology and even less about their behavior, but that is beginning to change. In the early days of shark research we only learned about white sharks by dissecting dead animals, or by observing them on or near the surface—only during the day, and mostly during feeding or baited situations. In the early days we did not learn very much, but we did not hurt the sharks either. In the past 10 years scientists began using modern technology, including dorsal fin satellite and acoustic tags and DNA techniques. This technology has begun to reveal how and where they spend most of their time. For example, we now know that white sharks spend the months of August through March at a handful of sites along the West Coast, including Guadalupe. Then they migrate west to a few locations but mainly to a spot researchers have dubbed the "Café". The Café is a relatively small area, roughly elliptical and the size of Vermont, about 1000 miles west of Cabo san Lucas. These data are obtained by the use of moderately invasive satellite tags that are attached by barbed hooks to the shark's muscle under the dorsal fin. The tags clearly injure the shark, but the information obtained seems to make up for the discomfort to a few sharks. The problem with these tags is they are programmed to detach from the shark in less than a year and can only then upload their data to a satellite after they are detached, and that many sharks have been repeatedly tagged.

In recent years shark research has taken on a controversial side. Dr. Michael L. Domeier and his colleagues, in an effort to collect more data, are capturing sharks to attach a new kind of shark tag. These tags are capable of uploading data every time the shark's dorsal fin breaks the surface, have batteries that can last for years, and have the potential for collecting much more data than the older tags. The sharks are taken with baited hooks, fought for an hour or more to exhaustion then hauled out of the water for 20 minutes or more. Four holes are drilled into their dorsal fins and they are subjected to invasive tissue sampling before they are released. A shark's skeleton is made of cartilage, not hard bone, and they are not designed to support their body weight out of the water.

National Geographic has presented these activities in a documentary dubbed "Expedition Great White". This documentary is tough to watch since it is mainly about hooking and landing a shark. There is concern about creating exciting television rather than actually acquiring data needed to manage and protect sharks. It is clear that technology is advancing at a rapid rate and better shark tags that do not require such harsh treatment of the sharks will be available soon.

So if you have ever considered taking a trip to see the sharks in their natural surroundings, consider Isla de Guadalupe.

Visit these majestic animals on their home turf, I promise, you will not be disappointed. ■