"Sharks are magnificent predators, and I want to poke into their private lives. These animals are wild, free, and one of the few creatures left that can challenge man. Because they are so formidable and mysterious, sharks have become shrouded in myths, portrayed as villains, and worshipped as gods. The question that drives me is, 'What's the real truth?'" --Dr. Samuel Gruber

It is often said that the eyes are the window to the soul. It is a saying that Sam Gruber must have had in the back of his mind when he was a young scientist in 1961, setting out to understand what makes sharks tick. Driven by a fascination with the sea and with the sleek hunters that dominate so much of that mysterious realm, Gruber started his research by looking sharks straight in the eye. Detailed studies of eyes and brains kept Gruber busy for 15 years as he focused on understanding the visual systems of sharks and rays. Like all truly exciting science, Gruber's research brought compelling new questions and contradictions to the surface.

"I was quite perplexed by what I had found. At the time, sharks were thought to have crude vision--to be almost blind. But my studies indicated exquisitely adapted visual systems."-SG

By using the scientific method--experimentation, observation, testing, repetition--Gruber disproved a prevailing misconception about sharks. And his toothy research subjects, swimming as much in mythos as in the shadowy depths, confronted him with countless popular misconceptions waiting to be examined, demystified, and set straight. Gruber dove right in.

In 1978, he obtained funding from the National Science Foundation (NSF) to start answering questions that extended beyond the function of shark eyes:

• What role does vision play in the behavior of wild Lemon Sharks?
• How do they interact with their surroundings?
• How, when, and where do they reproduce?
• How much energy do they spend hunting, swimming, mating?
• How do distinct local populations evolve their own characteristics, and how do they mix with other, nearby populations?

Witnessing the enthusiasm with which Dr. Gruber attacks and discusses the mysteries posed by sharks, it is hard to imagine him doing anything else for a living. Indeed, he has been single-mindedly pursuing his favorite subject since the summer of 1958, when a chance meeting intensified and narrowed his childhood interest in the oceans. In the scientist's own words,

"I was underwater spearfishing one day in 1958, and I had a close encounter with a 2000 foot long hammerhead. At least it seemed that big at the time! In short order, I enrolled in the University of Miami marine biology course and the rest is history."-SG

Forty years later, it is clear that Gruber still thinks that his office (even if his office happens to be a shark infested lagoon) is a very, very cool place to be.

Gruber Sets Sail aboard the Harbor Branch Research Vessel, SEA DIVER~

In August of 1998, Gruber's desire to understand Lemon Shark breeding dynamics brought him to Harbor Branch Oceanographic Institution, where he set sail for the shark-filled waters of the Marquesas aboard the Research Vessel SEA DIVER. As is the case with most of his research, Gruber was driven by fundamental, unanswered questions.

"Nothing at all is known about the breeding strategy of requiem sharks like the Lemon Shark...and they are the most evolutionarily successful kinds of sharks. They are apparently the most modern sharks as well. And they are the most heavily targeted group--fished and overfished for fin and flesh. So do we want to see them go extinct before we even know how they go about reproducing?"-SG

Gruber's SEA DIVER mission set out to test his hypothesis that Lemon Sharks, like salmon, tend to return to their birthplace to mate and give birth. He knew that if his subjects were returning home year after year to mate among their siblings and cousins, they would display evidence of a high degree of inbreeding. This evidence would be found in their DNA...if the hundreds of sharks sampled for their genetic material all proved to be close relatives, it would indicate that Gruber's hunch was a good one.

"We caught the little pups in a net at night and brought them to a tagging boat. The sharks were weighed, measured, and sex determined. Then, using a leather hole punch, we collected a 2 mm diameter piece of each pup's fin for DNA analysis. The sampled pups were put in a pen with all the others so we wouldn't catch them again. We fished until we had every lemon shark in that portion of the lagoon, then we released them knowing full well that we got them all.'

'DNA is extracted from our shark skin samples in Chicago by my colleague Mary Ashley and her student, Kevin Feldheim. Using a technique called PCR, Mary and Kevin make millions of copies of a special portion the DNA genome, called 'microsattellites.' These microsattelites show the individual variation between sharks, and we analyze them using the same photographic methods that everyone saw in the O.J. Simpson trial." -SG

The wealth of information provided by genetic testing during the SEA DIVER mission will allow Gruber and his colleagues to test another hypothesis, as well. Dr. Gruber believes that Lemon Sharks are on a two-year birth cycle--that mature sharks get pregnant one year and rest the next. If this is true, then every spring at the Marquesas breeding gathering, there will be two distinct types of female sharks swimming around--those who are about to have pups, and those who are just mating. Since one group of shark moms would continue to have pups on even years, and another group would give birth on odd years, the shark populations would tend to display distinct genetic patterns. Namely, sharks born on even years should be more closely related to each other (since they share the same set of moms) than they are to sharks born on the odd years. Genetic analysis will offer precise information as to whether this two-year maternal cycle is truly happening.

High Praise for the SEA DIVER and Her Crew~

When asked how the facilities aboard the Harbor Branch Research Vessel suited his needs, Gruber answers with characteristic enthusiasm.

"I really enjoyed my cruise on the SEA DIVER! Having been chief scientist on several research vessels over the past 3 decades, I am please to say how fine the condition of the SEA DIVER was--considering she is an old grand dame of the sea. We particularly liked the fireplace in the salon! The cuisine was...well...awesome!'

'My research team was most impressed with the enthusiastic help given to us by the ship's crew. In particular, the engineer, Pete, an amazing, salty character with a heart of gold, spent many hours teaching us how to repair nets the proper way. He wasn't alone. The whole crew pitched in whereever they could.'

'Our operation uses small boats and we work at night away from the vessel. Our operation was great for the crew because we were anchored for days on end and they love to fish. They were in fishing heaven! The downside for the ship was our nocturnal research, which made meals a bit difficult since the scientific and marine crews were on different schedules. The ships chief, Bob Stevenson really bent over backwards to accommodate us.'

'Really everyone made the extra effort to see us through the work--Capt. Mike and the first mate--all the deck crew were lots of fun to work with. We are hoping we can have the same crew next time we sail aboard the sea diver."-SG

The Research Continues~

On March 12, 1999, Gruber and his team will be setting sail with Harbor Branch again, this time aboard the R/V SEWARD JOHNSON. This mission to Atol das Rocas, Brazil will be covered LIVE in the Missions section of @Sea, so make sure to tune in! Gruber will continue his work on unraveling the mysteries of shark reproduction and hopes to determine whether his SEA DIVER findings from the Marquesas will apply to Lemon Shark populations elsewhere.

Sam Gruber is obviously a man on a groove. After 40 years of dedicated work, his chosen field of research continues to provide him with an unending supply of exciting challenges. Luckily, Gruber's energy level and enthusiasm seem as boundless as the mysteries he is seeking to explore and explain.

"My favorite thing to do is discover something new about how sharks work--and to transmit that information to the public. No myths--only facts and quantitative models of the lifestyle of this great fish!!! Someday, when your daughter or son asks about sharks, perhaps you won't have to rely on myths and propaganda. There are a lot of new facts out there, and because of this, I have seen a real change in the public's perception of sharks. I feel personally good about this change. In some small way I feel like I have been able to spread the 'truth.'"-SG