I’ve recently been interested in technologies that allow scientists to tag animals (and other things), and how those technologies have been getting smaller and more powerful– or rather, since that trend is pretty much a given, what difference it makes.

While catching up on my RSS feeds, I came across this report from May about tagging isotopes to track the migration of baby clownfish– sort of Jacques Cousteau meets Finding Nemo:

A team tagged two species of reef fish larvae to see where the juveniles were going after spending weeks and even months maturing in open sea.

It found most of the orange clownfish – made famous by the Finding Nemo movie – and vagabond butterflyfish returned to the reef where they had first hatched….

“Marine fish lay very small eggs, and when they do, they are released into the water column,” explained co-author Professor Geoff Jones from James Cook University in Queensland, Australia.

“They develop into a really tiny little larvae that we think drift around in the water currents, sometimes for months.

“The missing link in our understanding of coral reef fish has always been: where do the larvae go?”…

[To track the larvae, the scientists captured] female coral reef fish from a small 0.3 sq km reef in Kimbe Bay, Papua New Guinea, and injecting them with a rare, stable barium isotope.

The females pass this isotope to their developing offspring where it accumulates in their bones, giving the baby fish unique chemical signatures.

A few weeks later, the team returned to the reef and collected young fish to test them to see if they carried the “tag”.

“We found that 60% – well over half – were coming back to the small island reserve, which was an unexpected result,” Professor Jones told the BBC.