Fish Conditioning: Do fish become conditioned by contact with divers?


In Mauritius, some of the species are completely relaxed, and others extremely nervous around divers. The most remarkable are the sharks in the shark pit in Mauritius. We have been there with a small group to find as many as 23 sharks finning around in the washing machine current. To them we do not exist. They completely ignore us.

Once they have got used to the fact that the air-breathers are harmless they go about their business happily, unafraid of the invaders.

In Mozambique the Potato Bass are happy to interact with divers, lying on the sand, eyeing them hopefully, swimming beside them and rubbing against them. The legendary Bert was among these.

The controversy over Cage Diving and chumming for sharks rages on, and although we enjoy the adrenalin rush of the Tiger Shark Dive at Aliwal Shoal, there is always a nagging doubt that we are supporting something that could lead to later danger. It is extremely rare for a diver to be attacked by a shark, unless he is in a bait ball or in the wrong place, or behaves foolishly. The Dive Operators who offer these extreme experiences have never themselves felt in any danger.

The raggies at Aliwal shoal are like bull terriers. They are completely familiar with divers, and they are unfazed by photographers. The pregnant females at Sodwana fin trance-like around groups of divers.

I watched Walter Bernardis brush a piece of sardine away from my buddy’s head just as a Black Tip was diving for it, and the Black Tip veered away from his hand. Shark diving is exhilarating, but I have never felt threatened by the animals themselves. After five years of diving with the Tigers, I have noticed that the grey reef and black tips that come to feed are no longer wary of divers. They brush you out of the way to reach the bait ball. Once they lose their fear of divers, these sharks are completely relaxed in the water.

The one animal that always seems completely aloof, has never changed, and which completely ignores diver and which typifies the apex predator is the Tiger. Nothing changes their behaviour that I have ever seen. They are always looking for something to taste. They are always alert to anything new in their world. They will always nibble on anything unfamiliar, and a nibble from a tiger can remove most of your torso.

Is it a bad thing for fishes to become conditioned to the presence of divers in their private domain? Theoretically, anything that changes the behaviour of a creature in its natural habitat is unwarrantable interference. However, the test of stress in a creature is whether it continues to live, to eat and to breed and the evidence of stress-free fish life is everywhere.

In the bad old days, Dive Masters in Mauritius used to conceal pieces of uneaten cheap Government bread in their BC pockets. Unnoticed by the early naiive Resort Course divers, the DMs crumble the bread into the water around them, and are soon mobbed by shoals of damsels, who like nothing more than a little French loaf for breakfast.

When you dived with certain Dive Operators there you had to swat away the aggressively seeking damsels. They bit your hands or the naked areas on your face. Their teeth are too small to draw blood, but the nip was painful nonetheless. Conditioned to expect something from divers? Absolutely.

At Sodwana Bay on Stringer Reef and on Quarter Mile Reef the Sergeant Majors (Abdadufduf abdadufduf ) lay their eggs in nests in the hollows of the eroded rocks and caverns. In December they can be seen hovering anxiously over their nests, but if a diver gets too close they dart away, and the wily wrasses pile in and gobble their eggs.

Incredibly, the Wrasses know they fear divers, and we have often been plagued by colourful wrasses weaving seductively in front of the camera lens, and then darting towards the Sergeant Majors’ nests hoping we will follow them. It’s almost as though they are saying, “Come on guys, come and look at these eggs, come and photograph these fish.” We have often seen pairs of mournful-looking Sergeant Majors rushing back to their eggless nests after an oblivious dive group has finned down for a closer look.

Conditioning? Looks like it.

Less obvious conditioning is on new or undiscovered reefs, where the fish are much more nervous when a group of divers arrives, and whole shoals will fin away from the intruders. I’ve seen this happen at little –known Reefs like Fusilier, or Snapper College at Sodwana.

Perhaps, just as we are learning about Reef Fish, they are learning about us – and if their behaviour is anything to go by, once they get to know us, they simply accept us.

Words Jill Holloway

Pic David Holloway

Copyright Ocean Spirit

Jill Holloway

Jill Holloway

Jill Holloway lives in Mauritius and at Sodwana Bay Isimangaliso Wetland Park in South Africa. A PADI qualified Nitrox diver with over 1,500 dives, she is a passionate observer and preserver of the marine environment, and has a database of over 35,000 fish pics and hundreds of Gopro videos on fish behaviour, which she shares with her readers.

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