Do halibut leave Glacier Bay during the winter and if so, do they return the following summer? To try and answer this question Nielsen attached 25 fish in Glacier Bay with satellite tags [SeaTag-MOD] in the summer of 2013. Nielson is a PhD student at the University of Alaska Fairbanks' School of Fisheries and Ocean Sciences.
Tags scheduled to release in February popped off as expected and began transmitting their locations to satellites. “I was pretty much glued to the computer for weeks after that date,” Nielson said. “The idea was: If the halibut have gone on a spawning migration, their tags would pop off outside the Park.”
All of these tags transmitted locations within the Bay.
“I did not expect that at all; I thought we were going to find some that were out in the Gulf,” she said.
After popping off, Julie was able to recover the tags using the Argos goniometer. Tag recovery is necessary to download the tens of thousands of individual sensor readings (magnetics, accelerometer, depth, temperature, and light levels) that the tags record. While they can transmit raw sensor packets through the Argos satellite system, the bandwidth is limited and the likelihood of receiving 100% of the data is indefinitely low.
You can read the entire story through the link in the first paragraph. We wish Julie Nielsen the best in her upcoming work on her PhD, and if you have interest in tagging demersal fish know that SeaTag devices are your only option.