The giant fish, named for its disk-like shape, is usually found in tropical waters. But it’s not the first time this odd-looking creature – measuring up to 3.3m across and weighing an average of 998kg, it’s the world’s heaviest bony fish – has been seen off the Scottish coast. There have been more frequent sightings in recent years, on both sides of the country.
And this is not the only stranger that is turning up here more often. Other rare but increasingly common marine visitors include leatherback turtles, humpback whales and barrel jellyfish.
There has also been a major northward shift in the distribution of plankton and the timing of its production over the past half century or so. Meanwhile, research shows some fish have moved as much as 400km to the north in the past 30 years, with things like squid providing new targets for Scottish fishing fleets.
All this is being caused by climate change, which has seen the average sea temperature in Scotland rise by as much as 1C in the past 20 years. Experts predict this could rocket to 4C by the end of the century.
The flip side, however, is that we’re also witnessing the disappearance of many native species we think of as commonplace. Internationally important populations of puffins, kittiwakes and terns have plummeted in recent decades. Sandeels, which provide an important food source for many seabirds and other marine wildlife, are vanishing at a worrying rate. Scientists have also warned that commercially important fish such as cod, herring and haddock could be absent from west coast waters by the turn of the century.
To make things worse, our oceans and seas are getting more acidic as well as heating up, due to the unprecedented levels of carbon dioxide that have been swallowed up since the start of industrialisation. Increasing acidity causes serious problems for corals and shellfish, whose shells literally dissolve.
Studies suggest the biggest losers to climate change will be the tropical regions – partly because they are the most biologically diverse in the first place, but also because many species living there are already at the limit of their tolerance for warmth. This means we in the northern hemisphere could potentially see an increase in biodiversity as temperatures continue to rise, despite the loss of some of our own cold-loving species.
Scientists are predicting that hammerheads, threshers and other dangerous shark species could soon be found hunting beneath our waves. Locally caught anchovies, red mullet, John Dory and seabass could also soon be staples on restaurant menus.
These shifting populations illustrate how wildlife will adapt in order to survive. However, as much as we all love to hear reports of exotic creatures being seen in and around Scotland, we need to step up our efforts to hold back the worst effects of climate change.
A new report by scientists from the University of Manchester and Sweden’s Uppsala University claims the Scottish Government’s new climate bill, which proposes a 90 per cent reduction in all greenhouse gas emissions by 2050 compared to 1990, will see the country fail to meet obligations set out under the 2016 Paris Agreement. Instead it suggests we must aim for net zero emissions by 2050 to keep global temperature rise below 2C. It’s a tall order but the alternative is catastrophic.