Atlantic bluefin tuna – giants of the sea reaching up to two metres and 350kg – have been making a striking comeback off Ireland’s coast, with sightings surging around this time of year over the past decade thanks to international conservation efforts to protect the once-overfished species.

Feeding on herring, mackerel and other schooling prey, these creatures can live up to 40 years, making them among the longest-living fish to be found in Irish waters.

The species has also lent its name to one of Ireland’s biggest corporate deals of the year, with Irish Continental Group (ICG) chief executive Eamonn Rothwell naming Bluefin Bidco as the vehicle that last week launched a €1.21 billion takeover bid for the ferry operator he has led for almost four decades.

Rothwell’s story, like that of the fish itself, is one of endurance. A previous attempt to buy the listed Irish Ferries owner 19 years ago ran aground when developer Liam Carroll and a consortium led by businessman Philip Lynch’s One51 and Doyle Shipping each built up stakes, triggering a months-long takeover battle that ultimately ended in a stalemate.

His rivals, who were primarily drawn to the development potential of ICG’s Dublin Port site – held under a long-term lease – were later forced to sell their stakes during the financial crisis to reduce debt, crystallising substantial losses.