Meet the charismatic megafauna! The most famous residents in Kermadec waters are the spotted black groupers, and rightly so. These fish have presence, and it’s not just because they are big, solidly built and up to 1.7 metres long. There is something very stately about the slow way they swim, taking their time as they come by to check us out. They aren’t scared of us, and swim right up to us to get a good look (they’re very curious).
A fish with presence: the groupers grow up to 1.7m and cut a slow, stately figure in Kermadec waters © M Francis
As you’d guess, big also means old – they live to well past 50. But just to be tricky, like many fish species they change sex as they get older – they start off as females, and when they get to about 1-1.1 metres long they turn into males. So they get to be both mum and dad at different times of their lives!
And they don’t just change sex – they also have a great colour-changing trick. They can change from almost white to almost black (or the reverse) in just a few seconds. No one knows quite why, but it might indicate mood – people have seen two grouper interacting and rubbing past one another, and flashing from black to white and back again, and every shade of grey in between.
Agent of change: groupers change their gender during their lifecycle and their colouring can change in a matter of seconds © M Francis
Someone asked if we were catching sharks and the black spotted grouper. We are doing some line fishing from the boat, but any sharks or grouper we catch are measured, a tiny tissue sample is collected for genetic analysis, and then they are released again, to carry on being top predator and star attraction in this fabulous marine reserve.
