Disappointment came via an announcement from the GFAA yesterday that the satellite tag put in the broadbill swordfish on Saturday has detached. Unfortunately this early data unfortunately means this fish has died. I confirmed with Dr. Sean Tracey of the Institute for Marine and Antarctic Studies (IMAS) that I was able to share his explanation which is in his words below.
Dr. Sean Tracey IMAS
“They (the satellite tags) are rated as good to 1800 metres and have a fail-safe that will detach them from the fish if they go below this depth. Based on the depth data recorded (in this case), the tag went almost straight to the sea floor, stayed at 600 metres – basically the depth the fish was tagged over, and detached after 2 days as it was programmed to do if it stayed at a constant depth.
Either the whole fish sunk to the bottom or possibly it was bitten and part of the fish (with the tag) sunk.
Either way it is disappointing but there is still much to learn about this fishery, particularly the fish off Tasmania.
There have been several sat tagging studies in New Zealand and Australia (within the commercial fishery) as from the US from both commercial and recreational fisheries on swords. One of the big questions is are the fish off Tasmania an isolated population or do they migrate south annually. The sat tagging work in Australia does not show the fish migrating as far south as Tasmania (but this doesn’t mean they don’t). So we hope to get a few tags out on fish caught off Tassie (that survive) and see if they stay local or go walkabout.”
