Fish tags with iPhone technology are being used for the first time to track halibut migrations based on the earth&rsquo;s magnetic field.  Cash rewards of $500 are being offered to get the tags back so scientists can see how well they work.
&ldquo;This year the technology that everyone has been talking about for a decade but hasn&rsquo;t been able to miniaturize are tags that record magnetic field strength on three axes and have accelerometers and pitch and roll detectors.