A shark survey off the Pembrokeshire coast has been joined by Welsh Environment Minister Carwyn Jones, who has helped tag the fish.
The blue shark is the most common shark in Welsh waters
Members of WWF Cymru have tagged blue sharks as part of a project aimed at finding out more about their movement and behaviour.
The blue shark is the most common shark found in Welsh waters and are known to travel hundreds of miles each year.
When tagged, the shark's length, weight sex and condition are all recorded.
Morgan Parry, head of WWF Cymru, said: "The lack of information on blue sharks in UK waters is precisely what encouraged WWF to support the shark tagging programme.
"The aim is to contribute towards the protection of UK shark species by encouraging a catch and release responsible scheme.
The shark's vital statistics are recorded before it is released
"The tagging is a simple yet effective way to monitor shark movements.
"We have learnt that sharks tend to travel long distances and a high proportion of specimens tagged off our coast are in most cases caught again by Spanish, Portuguese and sometimes even Japanese commercial fishing fleets."
Mr Jones said such schemes would help develop a fisheries strategy for Wales.
"We want our seas to be clean, to support vibrant economies and healthy and functioning ecosystems that are diverse, productive and resilient."
Last year WWF tagged six blue sharks of the Welsh coast.
The sharks grow to an average length of 2.76m for females and 2.46m for males and live on fish.
Other sharks found in UK waters include the tope, smooth hound, porbeagle and thresher.