Aussie Researchers Show Baby Fish Have ‘Magnetic Compass’ to Guide Them Home

A group of international researchers on Thursday said they have made a significant stride in protecting and maintaining sustainable reef stocks after finding fish larvae have an internal “magnetic compass” to guide them home.

Reef fish hatch from eggs dispersed in the water column into a larval form and are usually at sea for days to months before returning to their home or settling on another reef. Once they have found a reef, they generally stay there for life.

It is generally considered that fish use the currents to find a reef to settle on, however, researchers at Queensland state’s James Cook University, collaborating with colleagues in Germany, found that larval Cardinal fish have a sense of direction.

After collecting fish less than one centimeter long on One Tree Island on Australia’s Great Barrier Reef, fish orientation was tested using the same magnetic field found where they were captured. It was not until they altered the field by 120 degrees, they saw a significant change in the direction the fish swam.

“This study is the first clear demonstration that reef fish larvae possess magnetic senses to orient them at night,” James Cook University professor of marine biology at the Australian Research Council Center of Excellence for Coral Reef Studies, Mike Kingsford said in a statement on Thursday.

“Up until now we only knew adult birds, marine mammals, sharks and boney fish have this in-built sense of direction.”

Previous research shows once larval fish get closer to their target, a homing process begins where odor, sounds and landmarks are sensed to find a reef.

Confirmation of night navigation means baby fish “actually have brains,” they know where they are going and are strong swimmers which gives them some control over which reef they settle on, rather than just being led by currents, Kingsford said.

“Knowing this, we can develop more accurate models of where larvae go to determine the best way to protect and maintain sustainable fish stocks,” Kingsford said.

The research was published in the scientific journal Current Biology. (PNA/Xinhua)JBP/EBP