Scientists are hoping to track the movements of Atlantic bluefin tuna around the Outer Hebrides.
Shoals of the bid fish spotted off the Western Isles in recent years are thought to be the result of warmer seas and climate change.
But little is known about where they breed or the routes they take when migrating away from Scottish waters.
Catching tuna is illegal in the UK but Harris Development Ltd (HDL) -
Small satellite tracking devices attached to the fish will keep a track on their routes across the ocean.
HDL said they have been “successful in seeking derogations for three vessels to fish for bluefin tuna in waters off the Western Isles.
“This scientific programme will complement similar work being carried out by other European coastal states.
“All fish will be caught, tagged and released.”
The recovery of fish species like mackerel and herring which tuna feed on is also thought to be a factor in their appearance this far north.
Large numbers of different species of tuna have been seen chasing prey off west off the Hebrides between late summer and the end of autumn.
Often tuna stay well below the surface but at times can be seen "busting" or breaching the water when feeding.
All fish caught would be released and freed back into the sea.
Special hooks which will rot will be used so if a tuna swallows the line, the gear will be cut and the stuck barb eventually withers.
Fishing expedition to study bluefin tuna off Hebrides
6 August 2020
Grant Fulton