Crown Prince Frederik of Denmark helps register and check tuna

Crown Prince Frederik of Denmark showcased his passion for wildlife this week as he took part in the registering and checking of tuna in Danish waters.

The father-of-four, 53, sported a wetsuit as he joined the nation's Minister of Food, Agriculture and Fisheries Rasmus Prehn in the sea, north of Skagen, as part of efforts to preserve tuna.

The fish previously roamed in Danish waters, but mysteriously disappeared in the 1960s without scientists knowing the cause, reported Nord News - but thankfully returned in recent years.

Scientists are yet to know the reasons why fast-swimming tuna disappeared from the area around 60 years ago.

This is the fifth year in a row that the researchers from DTU Aqua in collaboration with local anglers are noticing bluefin tuna in Danish waters. 

Just four tuna were tagged in 2017 but by 2020 the number of tagged tuna had increased to 116. 

Prince Frederick, who is the heir to the Danish throne, has been praised by social media users for actively getting involved in the preservation of tuna in Danish waters.