Giant Trevally, Caranx ignobilis, are big, smart, curious fish. Freddy and I nick-named this one Posei (short for Poseidon). He (a male according to his black dorsal colouring) is attracted to Freddy for two reasons.
First, Posei knows us. Giant Trevally are territorial and patrol their domains daily. This one lives in the mini-lagoon of Ilot Mato in New Caledonia and we have seen him here for many years and, of course, he has seen us snorkelling along the reefs in his domain. He likes to hang out just under our yacht, too. He knows we don’t spear fish or even catch them on hook and line. Divers who enter the water with spear guns will never see Posei (we hope). I once tested this hypothesis by entering the water with a pole (a boat hook) and Posei, who was just under the yacht before I got in, was nowhere to be seen for two days.
Second, when I took this photo both Freddy and I were wearing our new zebra striped leotards. We don’t look like „frogmen“ and the strong contrasting pattern changes our apparent motions so the reef fish, including Posei, are less afraid of us. The first day we wore the leotards on the reef we noticed that there were more fish than we normally saw in the same areas and they allowed us to come closer than ever before. It’s not camouflage – maybe just the opposite. Lion fish, sea snakes and other „dangerous“ sea creatures often adopt a reverse camouflage. These vividly striped creatures are also slow moving – like us. The suits protect us from stinging medusa (even fire coral), sunburn, and are one tenth the cost of a nice French Bikini.
We have used suits similar to these for years and they proved to be effective in frightening off sharks. The old suits had straight stripes and they were broader. The new suits with their wavy narrower stripes had a completely different effect on the reef sharks. Initially they took off as desired but then they came back, looked us over very carefully, and then stuck around. I was able to get closer to them then ever before – great for photography, not so great when 5 sharks at the same time take an interest in you.
Posei has been close to us while we were snorkelling many times over the years but when ever I turned my camera towards him I’d only get a photo of him swimming away. This time he stuck around and posed for me, sometimes swimming within inches of the fisheye lens. In this image Posei and Freddy are the same distance (about 2 metres) away from the camera and you can judge the size of the fish pretty well. Freddy is 1.5 metres from head to toe (not counting the flippers) so from the photo I estimate Posei to be about 1.2 metres long. The largest recorded specimen of Caranx ignobilis was 1.7 metres long and weighed 80kg so Posei is big even for his species.
I worry about Posei because fishermen consider GT to be one of the best „sport“ fish around. Here in New Caledonia tag-and release is now the norm for professional fishing guides and for fishing contests but a really big fish is often kept as a „trophy“ during tournaments. Even worse are the spearfishers – just about every snorkelling male human here is an avid spearfisher and one look at Posei and they would be after him. I often see the spearfishers (both commercial and for „fun“) hunting in packs, encircling patch reefs or swimming from different directions along the reef to trap unwary fish between them. With their high powered spear guns and metre-long flippers these guys are deadly.
However, large specimens of GT are often ciquatoxic and most fishermen and divers know they can be poisonous – so they are not caught or killed for food – just for fun.
Posei’s big eyes supposedly have special high density retinal cells that „see“ a panoramic image so they can detect the slightest movements. That plus the fact that Posei has already survived for many years in the lagoon at Mato where lots of weekend spearfishers have stripped the reefs of larger fish, gives Freddy and I some hope that Posei might be there to welcome us next time we return to Ilot Mato.