Sea Turtle Hatchlings Adrift at Sea Impact Adult Oceanic Migration Patterns

Sea turtle migrations aren't just impacted by what happens to the turtles as adults. It turns out that these massive migrations are affected by the turtles' past experiences as hatchlings adrift in ocean currents.

When sea turtles breed, they return to the beeches where they were born. After they breed, the adults typically migrate several hundreds to thousands of kilometers to where they usually feed. Until now, though, researchers have been unsure how these turtles choose their feedings sites.

In order to find that out, the researchers looked at what habitats the sea turtles would have encountered as juveniles. Although hatchlings are too small to track with satellite tags, they drift with ocean currents after emerging from their eggs. This means that scientists can model ocean currents in order to see where hatchlings move after leaving their eggs on their nesting sites.

"Hatchlings' swimming abilities are pretty weak, and so they are largely at the mercy of the currents," said Rebecca Scott, one of the researchers, in a news release. "If they drift to a good site, they seem to imprint on this location, and then later actively go there as an adult; and because they're bigger and stronger they can swim there directly."

That's not all that researchers found, either. If the hatchlings don't drift to a suitable feeding site, they tend to feed in the open ocean as adults-or simply don't migrate.

"Although it is known that ocean currents have a large influence on the dispersion of small planktonic organisms, these findings reveal ocean currents also directly shape some of the migrations of some of the largest, most powerful long distance migrants in the animal kingdom," said Bob Marsh, one of the researchers, in a news release.

The findings reveal just how turtles decide on their migration routes. It turns out that ocean currents and where they drift as hatchlings largely influence where they will travel as adults.

The findings are published in the journal Ecology.