Some Big Sharks Take Small Bites

When we think of sharks, we think of single-fin predators with massive jaws slinking through the water in search of its next victim for a gory meal. This may apply for hammerhead and tiger sharks but for other shark species, not so much.

Actually, a new study on reef sharks from the Great Barrier Reef reveals that most coral reef sharks like black-tip, white-tip and grey reef sharps prefer infrequent small meals. They are also rather low on the food chain and, in turn, are themselves often eaten by tiger and hammerhead sharks.

Dr. Ashley Frisch, lead author and researcher at James Cook University’s ARC Centre of Excellence for Coral Reef Studies writes,

We were surprised to find a broad range of small prey items such as fish, mollusks, sea snakes, crabs and more often than not, nothing at all.

The researchers studied the stomach contents and analyzed tissue of reef sharks to estimate diet, trophic position and carbon sources.

Frisch added,

Although black-tip, white-tip and grey reef sharks have long been thought of as top predators, we found that the chemical structure of the shark’s body tissue actually matched closely with that of large reef fishes such as groupers, snappers, and emperors. The results tell us that reef sharks and large fishes have a similar diet, but they don’t eat each other. So rather that eating big fish, reef sharks are eating like big fish.

Co-author of the study and researcher Dr. Justin Rizzari said that this new research changes how scientists think about the food chain on coral reefs and remind us that conspicuous predators are not always on the top of the food chain. Tiger sharks, hammerhead sharks and people are the top predators. Humans pose the greatest threat, killing an estimated 100 million sharks every year. All of this impacts coral reefs, which are on the decline.

Dr. Rizzari writes,

Coral reef ecosystems are very complex. The more we realize that each and every species plays an important role. Sharks are no exception. They help to keep coral reefs healthy and should be managed wisely.

This study shows how changes in one population impacts another. It also reveals that some sharks prefer small-plate cuisine.