Groupers are enormous fish. Some species grow over two meters long and weigh hundreds of kilograms. Unfortunately for groupers, they are also delicious fish. Since prehistoric times, humans have been devouring all kinds of grouper species all over the world.
Such long-term fishing pressure tends to reduce fish size, as well as reducing the number of fish in the sea. Certain species, like the dusky grouper in the Mediterranean, have been fished for so long that we don't even know what a pristine population would look like.
Fortunately for groupers and for the scientists studying them, these fish are aesthetically appealing as well as huge and tasty. Dusky groupers can be recognized in Etruscan, Greek, and Roman artwork dating back thousands of years.
Paolo Guidetti of the University of Salento in Italy and Fiorenza Micheli of Stanford's Hopkins Marine Station studied this ancient art for biological clues. Frequent depictions of enormous fish in shallow water, including one swallowing a person, led them to conclude that today's small, deep-water dusky groupers are not the species' natural state.
Of course, as the authors point out, "there are no known instances of dusky groupers attacking human swimmers." Could the size of the fish have been similarly fabricated? Simon Blanford of Penn State University and Andrew Stoehr of Denison University took up this question with humorous gusto.
"Like Giudetti and Micheli, we too are biologists; however, the two of us additionally participate in a seamier pastime whose nature often involves--how can we put this?--a certain economy with the truth. We are fishermen." Having thus coyly introduced themselves, they express their concerns with the source material. "One can easily imagine a Roman painter, suffering from a bit of artist's block as he sits behind the virginal surface of a new amphora, slipping away from his garrett in the Bohemian district of Neapolis to do a bit of on-the-spot research . . . should the docks be barren, he would have been told he should have been there yesterday, when the quayside was so full of large fish they had to walk over them just to get about." They go on to cite Monty Python and Three Men In a Boat--it's far more amusing than I usually expect from a peer-reviewed journal.
But Micheli and Guidetti currently have the last word, having published a response in the most recent
episode issue of the reality show journal Frontiers in Ecology and the Environment. They point out that historical records and archaeology agree with the artistic evidence that dusky groupers were once larger and shallower. And while ancient art depicts many different kinds of fish, "when Roman artists wanted to represent a big fish (including a 'sea monster'), they frequently selected groupers as the subject."
That may be the end of the matter, but if not, I certainly look forward to the next installment.