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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 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.


Book Release: Diving the Thistlegorm – The Ultimate Guide to a World War II Shipwreck



Diving the Thistlegorm is a unique in-depth look at one of the world’s best-loved shipwrecks. In this highly visual guide, cutting edge photographic methods enable views of the wreck and its fascinating cargo which were previously impossible.

This book is the culmination of decades of experience, archaeological and photographic expertise, many hours underwater, months of computer processing time, and days spent researching and verifying the history of the ship and its cargo. For the first time, Diving the Thistlegorm brings the rich and complex contents of the wreck together, identifying individual items and illustrating where they can be found. As the expert team behind the underwater photography, reconstructions and explanations take you through the wreck in incredible detail, you will discover not only what has been learned but also what mysteries are still to be solved.

Find out more about:

  • One of the world’s greatest dives.
  • Incredible ‘photogrammetry’ shows the wreck and cargo in a whole new light.
  • Meticulous detail presented in a readable style by experts in their respective fields.

About the authors:

Simon Brown is an underwater photographer and photogrammetry/3D expert who has documented underwater subjects for a wide range of clients including Historic England, Wessex Archaeology and television companies such as National Geographic Channel and Discovery Canada. Jon Henderson is Reader in Archaeology at the University of Edinburgh where he is the Director of the Underwater Archaeology Research Centre. With specific research interests in submerged prehistoric settlements and developing underwater survey techniques, he has directed underwater projects in the UK, Poland, Greece, Italy, Egypt, Jamaica and Malaysia. Alex Mustard is a former marine biologist and award-winning underwater photographer. In 2018 he was made an MBE in the Queen’s Birthday Honours list for “Services to underwater photography”. Mike Postons pioneered the use of digital 3D modelling to visualise shipwrecks, as well as the processes of reconstructing original ships from historic plans. He has worked with a number of organisations including the National Oceanic and Atmospheric Administration, Historic England and the Nautical Archaeological Society.

About the book:

  • Release date 25 November 2020
  • Limited run of Hardbacks
  • RRP £35
  • ISBN 978-1-909455-37-5
  • 240 photo-packed pages
  • 240 x 160 mm

Available to pre-order now from, Amazon, online, and from retailers.

Check back on for a review of the book coming soon!

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Deptherapy’s Dr Richard Cullen becomes a Fellow of the Royal Geographical Society



Dr Richard Cullen, Chairman of Scuba Diving Rehabilitation Charity Deptherapy and Deptherapy Education, has been recognised as a Fellow of the Royal Geographical Society.

Fellowship of the Royal Geographical Society is a prestigious Fellowship that is open to those who demonstrate a sufficient involvement in geography or an allied subject through publications, research or professional experience.

Paul Rose, Deptherapy’s Vice Chair, and a world renowned explorer, author, broadcaster, who is a former Vice Chair of the RGS said: 

“This is a huge achievement by Richard. His Fellowship is richly deserved, and a direct result of his steadfast commitment to preserving our oceans through Deptherapy’s very powerful ‘Protecting Our Oceans’ Programme.  I know the top team at the RGS are looking forward to welcoming Richard into the Society.”

The RGS was founded in 1830 to advance geographical research, education, fieldwork and expeditions, as well as by advocating on behalf of the discipline and promoting geography to public audiences.

Paul Toomer, President of RAID, said:

“I have been close friends with Richard for many years and his passion for our seas, even at 70 years of age, is undiminished.  Deptherapy are the world leaders in adaptive scuba diving teaching and are our much valued partners.  Taking UK Armed Forces Veterans who have suffered life changing mental and/or physical challenges and engaging them in major marine biology expeditions, is to most of us beyond the realms of possibility.  The skills these guys have to develop is just awesome.  This is a great honour for Richard, a great honour for Deptherapy, and also for us as their partners.  The diving world must come together to celebrate and acknowledge Richard’s achievement.”

Richard joins some distinguished Fellows of the RGS.  Former Fellows include Ernest Shackleton and many other notable explorers and geographers.

Richard said:

“I am both honoured and humbled to become a Fellow of the Royal Geographical Society. When I was invited to apply for a Fellowship, I was, which is very unusual for me, lost for words.  I hope it will allow me to take our message of Protecting Our Oceans to a larger audience and to further develop our programmes.  The Fellowship is a recognition of the charity’s work to raise awareness of the plight of our oceans.  The credit belongs to a group of individuals who have overcome massive challenges to let alone qualify as divers but now to progress to marine biology expedition diving”.

For more information about the work of Deptherapy and Deptherapy Education visit

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Sharks Bay Umbi Diving Village is a Bedouin-owned resort with stunning views and a lovely private beach. It is ideal for divers as everything is onsite including the resort's jetty, dive centre and house reef. The warm hospitality makes for a diving holiday like no other. There is an excellent seafood restaurent and beach bar onsite, and with the enormous diversity of the Sharm El Sheikh dive sites and the surrounding areas of the South Sinai, there really is something for every level of diver to enjoy.

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