Hitting the Shoal

One of my favourite spectacles underwater are the ‘bait balls,’ conglomerations of small fish grouping together, tightly packed for protection from predators. These are especially common on the Cargo Wreck where thousands of fusiliers (Caesionidae) can be seen often in amorphous fluidity.

Not exactly a bait ball, but a shoal of fusiliers heading past.

Close up they are quite a beautiful fish

They are especially prolific when there’s a bit of a current and some plankton in the water and while fascinating to watch by themselves, the action really starts when a few Bonito show up. These medium size tuna hunt in small packs of five to eight fish and are capable of simply jaw-dropping bursts of speed.

There is nothing that can compare to the adrenaline rush you get watching these in action. I’d only seen these fish dead on a block of ice at a supermarket before I started diving so the speed and agility which these fish displayed was mind-blowing (I’m of course rapidly running out of superlatives to describe the action). You first notice them as a faint silver streak out of the deep blue. If they pass overhead you can see their slim silhouettes black against the backdrop of the sun glittering through 30 meters of water. You can see them flex their fins, moving them in and out as if warming them up for the rush into the shoal.

You have to keep a close eye on them at this time because even if you look away for a second, you can miss the lightning attack. From almost a standing start, they seem to pick a target and dart into the shoal of fusiliers, a blur as your eye struggles to follow. The bonito arrow is followed by the shoal of fusiliers splitting to avoid the attack, the fish moving as if with one mind. One bonito after another darts into the shoal, the fusiliers desperately trying to avoid the incoming fish. An underwater ballet unfolds that is beautiful to watch but deadly serious. Flashes of tuna and clouds of fusiliers playing a game of life and death, slowest one loses.

(Unfortunately my camera is too crap to capture these images but if you click here, you can see some baitball images that DJ has taken.)

This fusilier obviously caught the wrong end of someone's stick

Whenever I see shoals of fusiliers over the Cargo I always hang around in the water watching them while the uninitiated remain too busy looking at the ship to notice the hunters approaching. One of the seminal moments of the last season was when I was amidships close to one of the masts by myself as the hunters circled. A bonito came tearing into the fusiliers right at me, missed his kill and arched up past my bubbles back into the blue.

A grace under water that has truly to be seen to be believed.