You may have heard the old saying, "There are plenty of fish in the sea." But just how many fish are in the world's oceans?

Scientists may now have the answer to the age old question thanks to the first fish census.

The study involved 27 researchers from 80 different countries. They worked more that 9,000 days and completed over 500 separate expeditions from the Arctic Circle to the Southern Ocean.

The result is a giant data base for scientists to measure how temperature changes and other factors impact ocean life.

"Not only do we understand more about individual species, but we understand how they relate to one another and that is incredibly important," the Zoological Society of London's Dr. Matthew Gollock said.

Researchers say future scientists will study the data to measure trends and see how the ocean is changing.

In the end, the study estimated that the oceans contain more than a million species of marine life. But researchers say scientists have only seen about a quarter of that number.