A year has passed since ray tagging, and we can finally look at the data we have collected

Last summer, we tagged 26 gorgeous thornback rays in Osterfjorden, just a bit north of Bergen. Most of them were captured with rod and reel baited with mackerel, while a few were captured on a longline. Both the hooks on the rod and the longline were debarbed to minimize the impact of being captured, which is an important aspect when using telemetry to study fish in the wild.

A tagged thornback ray being released back out in the fjord

We intensively covered a small area of the fjord with 15 acoustic release receivers to be able to estimate accurate positions of the tagged rays when they were within the area. We have now been back and released the receivers in the array.

One of the buoys with the acoustic receiver after reaching the surface

Now that the data is downloaded and we have several million detections from the 26 individuals, we will start the data analysis to check aspects such as movement patterns, habitat use, residency vs migratory patterns, and interactions.

The receivers and their buoys needed some cleaning after being deployed for a year