Newsletter - 03/08/2001

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The Loggerhead

The Official newsletter for The African Diving Experience
www.africandiving.com
Volume 9 Date: 03/08/2001

We hope you enjoy the August issue of our monthly newsletter.

Index:

<1) What's happening on the African Diving Experience
<2) Shark of the month  - Basking Shark
<3) Fish Identification tips - Masked coachman, the normal Coachman and the Moorish idol
<4) Book Review  - Small boat diving by Steven M. Barsky
<5) Forth Coming Events
<6) Equipment Specials
<7) Web site of the month
<8) How to stay clear of the panic zone.

1. What's happening on the African Diving Experience

As promised in the July issue of the Loggerhead, we have been adding some information to the contents of the site. The following items have already been added:

     The Moray articles by The East Coast Fish-Watch Project, as seen in Divestyle.
     Diving Locations: Diving in Umhlanga Rock's with a few more on the way.

We would just like to add a special thanks to the following companies for contributing dive site information to our list of diving locations: Keryn's Dive School in Port Alfred, Dive Nautique in Umhlanga Rocks, Orca Industries in Claremont, The Whaler in Umkomaas and Alpha Dive center in Gordon’s bay. Unfortunately we where not able to have all the new information uploaded to the site but we will have it up soon.

On 29 July 2001 we where invited to attend the launch of Dive Lockers new dive club. The event was in the form of a mid-winters dive at Bass Lake. With water temperature at 14oC it was a bit cold but non the less we had a fantastic day. Thanks to all who made the day possible.

Interested in a banner exchange? Do contact us at the following e-mail
willem@dpa-training.co.za

2. Shark of the month - Basking Shark / Koesterhaai
Class: Chondrichthyes (Cartilaginous fish)
Sub class: Elasmobranchii (Sharks and rays)
Order: Lamniformes (Mackerel sharks)
Family: Cetorhinidae (Basking sharks)
Genus: Cetorhinus maximus (Basking shark)

The Basking Shark has a very long, cylindrically shaped trunk and a very pointed snout, with a large, sub terminal mouth, with minute hooked teeth and big eyes. Extremely large gill slits that nearly extend ventrally and dorsally around the head helps distinguish this shark from many others. It's first dorsal fin is large, erect and triangular with it's origin, well behind the free ends of the pectoral fins. The second dorsal fin is much smaller than first one. It's body is covered with placoid scales and has a blackish colour. It has a maximum total length of about 1520cm with, an average size, between 900cm and 1000cm. It is rarely
caught under 300cm with the smallest specimen ever caught, sized at 170cm.

Basking sharks live over the continental shelves in pelagic but not oceanic waters. They are highly migratory, with seasonal appearances in certain localities and subsequent disappearances. They can be found alone or in aggregations of up to 100 animals. They are found on the bottom of deep water during winter. Basking sharks are probably the original subject of the 'sea monster' stories since they prefer to swim directly under the water surface, with their dorsal and caudal fin penetrating the surface, and sometimes follow each other.The Basking Shark feeds by filtering copepods, barnacles, decapod larvae, and fish eggs from the water. They are able to filter about 2000 tons of water per hour. Basking sharks are nearly positively buoyant
due to their large livers, up to 25% of their total weight, that are filled with certain oils.


Basking Sharks are aplacental viviparous (ovoviviparous), probably with an uterine cannibalism. Their size at birth and litter sizes are unknown since, pregnant females are hardly ever caught. Males seem to reach sexual maturity between 400 to 500cm The Basking Shark is considered to by very sensitive to over fishing, ascribed to its slow growth rate, lengthy maturation time, long gestation period, low fecundity and probable small size of existing populations. Basking sharks are legally protected in some territorial waters. They are utilised fresh, frozen and dried, or salted and is also valued for its liver (for oil), fins (for soup), hide (for leather) and carcass (for fishmeal).

It is regarded as ordinarily harmless and inoffensive but potentially dangerous if attacked (particularly when harpooned).

Picture

source: http://www.shark.ch and http://www.fishbase.org

3. Fish Identification tips - Masked coachman, the normal Coachman and the Moorish idol

Some people find it difficult to distinguish between the Masked coachman, the normal Coachman and the Moorish idol. Hope fully these few tips will help you to identify these fish more easily.
Location of stripes:

Coachman - has two or three dark gray bars sloped across the body.
Masked coachman-has two, well defined black bars vertically across the body.
Moorish idol - has three, well defined, vertical black bars on the body.

Colour of snout:

Coachman – has a whitish snout with a thin black bar across the eye.
Masked coachman – has a thick black bar covering the snout and eye.
Moorish idol – has white snout tipped with black and has a yellow bar across the top. A thick black bar                      covers the eye.

Colour of tail, anal and dorsal fins:

Coachman – has yellow dorsal and tail fins with the only the fins coloured, anal fin is white and black.
Masked coachman – has yellow dorsal and tail fins but the yellow goes onto the body. The anal fin is yellow as well.
Moorish idol – has a black tail fin. The anal fin is black and white. The body has a white colour with some yellow from the dorsal fin to the tail.

All the above-mentioned fish has an elongated dorsal fin, which may be a half to two times the overall body length. To view pictures of these fish visit the Internet version of this newsletter on http://www.africandiving.com/

4. Book Review - Small boat diving by Steven M. Barsky

Small Boat Diving is a book for the diver who is interested in owning and operating his own small boat, as well as for the person who wants to get the most out of diving from small boats. The book includes detailed information on selecting and outfitting a boat, trailing, and diving operations. Everything in the book is covered from the diver's perspective. If you have never owned a boat before, or even if you are an experienced boat operator, you will find new and useful information in Small Boat Diving. You'll learn how to optimise your diving operations whether you use your boat for recreational diving, scientific diving, or search and rescue operations.

Included are chapters on the following topics:
• Introduction to Small Boat Diving
• Selecting Your Dive Boat
• Outfitting Your Dive Boat
• Accessories
• Transporting and Launching Your Dive Boat
• Diving from Small Boats
• Maintaining Your Dive Boat and Trailer
• The Adventure of Small Boat Diving

Small Boat Diving by Steven M. Barsky, Published by Best Publishing
To order this book go to:
http://www.hammerheadpress.com

5. Forthcoming Events

Open, shark feeding workshop - 22 August 2001 in Umkomaas

Watersport Africa Show - 31st August 2001 - 2nd September 2001, SuperSport Park, Centurion, South Africa, for further information, please contact Ross Harris - 082 824 7204 or e-mail to watersport@rai.co.za or visit
http://www.rai.co.za/watersport

6. Equipment Specials

We promised that we will inform you of all equipment specials as we become aware of them. Well here is a huge one:

SCUBAPRO and UWATEC is 25% sale on all SCUBAPRO and UWATEC products. To good to be true? The offer is in connection with Divestyle magazine. Around the July/August edition of Divestyle there is a black band which acts as a voucher for the purchase. The voucher is valid until 24 August 2001 and certain conditions apply. Definitely worth looking into.

Be on the look out for other specials as this is the time of the year that specials seems to pop up the most.

For more information's about specials or any equipment related queries contact Richard at:
info@oceandivers.co.za

7. Web site of the month
The following site is our choice for web site of the month:

http://www.adventurediving.co.za

Here is an interesting site about diving in the Cape. Move your mouse pointer over their map, to view
information about various diving locations in and around Cape Town

8. How to stay clear of the panic zone.

Panic is one of the leading causes of SCUBA diving accidents. Here are a few tips on how to avoid panic attacks:

Don’t dive beyond your capabilities: If you are not trained for the dive do not do it. A buddy’s training does not replace your own.
Don’t push the limits: Don’t squeeze in another dive just before you as fatigue may set in and it may be your last dive.
Don’t attempt a dive your not equipped for e.g. I’ll just go a short distance into the cave since I do not have a guideline or torch.
Keep your basic skills up to date: Practice your basic skills (mask clearing, buddy breathing) regularly as you never know when you might need them.
Go with your gut: If something does not feel right, don’t dive. Even if you are qualified and have done similar dives hundreds of times.
The ability to react constructively to an underwater situation is just as important as physical and mental fitness.

Source: Rodales scuba diving: Tips on diving like a pro.

Updated on: 06/03/2003