Jumping Jack Flash

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When I was paddling the other night I noticed there were more fish jumping than usual. The line from an old Stones record came into my head

Jumping Jack Flash ~ It's a gas, gas, gas !

But why do fish jump?


One reason fish jump is to chase insects skimming across the surface of the water. Perhaps at sunset when the sun is low on the horizon the insects are more easily seen and attract the fish.


But we often hear fish jumping at night. What we hear is the thwack of the belly flop they make when re entering the water. What do they see at night?


Another reason fish jump is to escape predators. These jumps usually occur in groups of fish not individuals and the fish retain an upright posture and re-enter the water cleanly. Rule that theory out... Ours are noisy, inelegant jumpers.

Photo - permission to use kindly given by Robert Harrington

A new theory that explains why these fish in our river, which are mullet, jump proposes that they jump to fill the pharyngobranchial organ, an area at the back of the throat, with air. The trapped air allows them to remain active in water of low oxygen concentration for about five minutes. Mullet often feed in bottom sediments which have low oxygen concentration and the number of jumps is correlated with the level of oxygen in the water. So, as Mick said, it could be all about gas...


Whatever the reason is for this phenomena, the sight of jumping fish is one of those things that makes you stop for a moment ... and wonder ... and be filled with awe... ~ and that is a good thing ...

Jumping jack flash, its a gas
Jumping jack flash, its a gas
Jumping jack flash, its a gas
Jumping jack flash, its a gas
Jumping jack flash


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