Fish – Page 3 – Learn to Dive Today Blog

Newsletter: Seasonal changes

Hi divers

Weekend dive plans

Staying dry

Both days this weekend have swell, and wind blowing from the wrong direction, and the current dark colour of False Bay means we are definitely staying dry. The weather does look better on Monday and Tuesday for those that have a flexible work schedule – if you’re one such, get in touch.

Binoculars for Shark Spotters

The Shark Spotters team are running a crowd funding campaign to raise money for new, high powered binoculars for the spotters. I can tell you that the right pair of binoculars makes all the difference. Cape Town’s Shark Spotters program is an international model for a beach safety solution that protects both sharks and people. They are very deserving of your support – please consider contributing to the campaign at this link.

Citizen Science Day

I promised to remind you again about the SANBI Citizen Science day, and it’s rolling around this weekend. There’s a full program of short lectures from representatives of various projects on Saturday, free of charge, in the conference venue at Kirstenbosch Gardens. There’s more detail at this facebook event link, and a list of the talks here.

regards

Tony Lindeque
076 817 1099
www.learntodivetoday.co.za
www.learntodivetoday.co.za/blog/

Diving is addictive!

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Bookshelf: The Annotated Old Fourlegs

The Annotated Old Fourlegs – Mike Bruton (and Prof J.L.B. Smith)

This is a beautifully designed and produced annotated version of Old Fourlegs, J.L.B. Smith’s account of the discovery and positive identification of a living coelacanth in 1938. Wide margins around the original text allow Mike Bruton to bring Old Fourlegs up to date with additional scientific information, as well as photographs, explanations, and other curiosities.

Old Fourlegs describes the months in 1938-1939 during which Smith confirmed the identity of the coelacanth with the essential assistance of Marjorie Courtenay-Latimer of the East London Museum. Ms Courtenay-Latimer acquired a fish specimen from a trawler captain, and, realising that it was an exceptional find, contacted Smith, an ichthyologist at Rhodes University. A rollercoaster of events – which involved the chartering of a South African Airforce plane and stretched all the way to then-Prime Minister D.F. Malan – was set in motion. Old Fourlegs is a surprisingly emotional, thrilling book by a man deeply invested in his work, and whose world was upended by the discovery of living coelacanths in the waters of the southern Indian Ocean.

It is also a book of its time, and today’s readers will find some parts by turns mystifying, and others offensive. The offensive bits – including lionising D.F. Malan, who, with his government, laid the foundations of the edifice of South Africa’s apartheid legislation – remain so, but Bruton’s annotated version provides context for readers unfamiliar with the history.

The book concludes with an examination of the cultural legacy of the coelacanth, which is disproportionately significant. The fish also has deep and wide links to South Africa and our research and diving community. If you have the appropriate (very deep diving) qualifications, you can dive with them in Jesser Canyon in Sodwana Bay. If you’ve never seen a video of one of these magical animals in motion, I encourage you to hit up youtube. Watch with the sound off for best effect.

Get the book here (South Africa), here or here. This is a volume you should read in hard copy, not as an ebook.

Farewell (for now) to the short tailed stingrays

This my the final video (for now) of short tailed stingrays (Dasyatis brevicaudata) swimming under the boat on a sunny February day in between dives.

[youtube=”https://www.youtube.com/watch?v=N1Sw21CYMAo&w=540″]

The IUCN Red List has these rays as of “least concern”, but they are protected in Western Australia because of their tourism value. There are locations in this region where tame stingrays interact with visitors; much like the rays at Struisbaai harbour.

More stingrays under the boat

We spent quite a bit of time with the short tailed stingrays (Dasyatis brevicaudata) between dives this past summer. Here’s another short video of one under the boat in shallow water.

[youtube=”https://www.youtube.com/watch?v=ERlIQJvAxvg&w=540″]

These rays can grow to over two metres in diameter and weigh a few hundred kilograms at their maximum. They are a popular target for fishermen.

Newsletter: Traditions

Hi divers

Weekend dive plans

Boat dives on Sunday or Monday / Shore dives on Monday (conditions dependent)

Traditionally Easter is a difficult time for diving. Many people are away and the weather does not always play ball. Add to this the traffic congestion from the Two Oceans marathon on Saturday… This weekend we may dive from Hout Bay on Sunday or Monday, or perhaps shore dives from Long Beach, wind dependent.

We are out tomorrow on a full day private charter but I do think Long Beach will be a good option if you feel like shore diving.

We send well wishes to everyone celebrating a religious observance this weekend. For those of you who celebrate Easter, here’s an egg for you:

Plastic and Water

On the marathon topic, watch this video and see how the Two Oceans Aquarium and Old Mutual are teaming up to reduce the use and impact of single use plastic, and learn about the aquarium’s turtle rehabilitation program.

This article on how to responsibly stockpile (or just purchase) bottled water, is very helpful if you’re working on water security at home, but don’t want to contribute to an environmental apocalypse.

regards

Tony Lindeque
076 817 1099
www.learntodivetoday.co.za
www.learntodivetoday.co.za/blog/

Diving is addictive!

To subscribe to receive this newsletter by email, use the form on this page!

Stingray in the sunshine

Here’s another view of one of the short tailed stingrays (Dasyatis brevicaudata) in the sunshine last month. Surprisingly little is known about these animals. They’ve been studied in Australia and New Zealand where they are also found, but not much work has been done to learn about them here.

[youtube=”https://www.youtube.com/watch?v=rI5h-L6Wzi0&w=540″]

If you have watched the original BBC Blue Planet series (if you haven’t, why not?) you will have seen the massive aggregations of these rays that form at the Poor Knights Islands off New Zealand. I wonder if there are any similar aggregations off the South African coast that we don’t know about?

Watching stingrays from the boat

We visited this beautiful short tailed stingray (Dasyatis brevicaudata) near Millers Point between dives one day in mid February. They’re commonly seen during the summer months, when water temperatures in False Bay are between 16 and 22 degrees celsius.

[youtube=”https://www.youtube.com/watch?v=iHz6Ar-XejQ&w=540″]

I find them to be more curious about the boat than they are when we see them during dives. Then, they’re most often resting or eating on the sand, and after a short time they swim away.

Newsletter: High hopes

Hi divers

Weekend dive plans

Saturday: Meet at the False Bay Yacht Club Parking at 9.00am for a double tank dive

The south easterlies are not ready to leave yet for the winter, but they are giving us a break right now. The forecast is for strong westerly wind tomorrow which will, if it blows, clean up False Bay rather nicely for some good visibility on Saturday. There is a 3 metre swell arriving on Saturday but I think it will be fine for a dive or two, and the tides are in our favour.

We will meet at the False Bay Yacht Club Parking at 9.00am. We’ll double tank it and choose the sites once we’re out there. Let me know if you want to be on board.

Giant short tailed stingray at Millers Point

I had a couple of good days on the boat this week, the highlight being watching this huge giant short tailed stingray on a flat calm day.

Water

We shared a blog post about diving during a drought this week. Check it out! Also, the WWF’s fourth Wednesday Water File was published yesterday, and it’s very pertinent. It’s all about toilets. Read it here.

regards

Tony Lindeque
076 817 1099
www.learntodivetoday.co.za
www.learntodivetoday.co.za/blog/

Diving is addictive!

To subscribe to receive this newsletter by email, use the form on this page!

Hunting rockcod and moray eel in Sodwana

This is a really cool bit of behaviour that I filmed on a dive to Pinnacles on Two Mile reef while we were in Sodwana last September, and one of my favourite things of all that we saw. A malabar rockcod (Epinephelus malabaricus) – as identified by our dive guides – in dark hunting colours, patrols the reef ahead of a honeycomb moray (Gymnothorax favagineus). At the time I didn’t know what was happening – it looked as though the eel was stalking the grouper – but it turns out to be more complicated and more interesting than that. I had filmed a subset of a total pattern of behaviour, in which the moray and rockcod (from the family of fish also called grouper) were hunting co-operatively.

[youtube=”https://www.youtube.com/watch?v=YzU9_cRW97E&w=540″]

A researcher at a Swiss university discovered in 2006 that coral groupers seek out giant moray eels (both of these species live in the Red Sea), summoning the eels from their dens with a vigorous shaking of their bodies. The fish and the eel then swim together looking for prey , a deadly tag-team of hunters. The groupers are fast in open water, but the eel can get into crevices to flush out prey. It is this behaviour, executed by a different type of eel and a different type of grouper, that I saw in Sodwana.

The scientists reported that the groupers use a head-stand signal, combined with a shaking of their bodies, to indicate the location of hidden prey to the eels. When the eels see this, most of them swim towards the grouper, and flushed out the prey.

You can read more about the study that revealed the extent of this behaviour here, and the actual paper reporting the research here. The scientists also discovered two other species with complementary skills that hunt co-operatively, on the Great Barrier Reef this time: the coral trout, and octopus.

Moray eels look incredible when they swim freely across the reef. Here’s one doing just that, in the Red Sea.

On the reef in Sodwana

We wrap up the videos from Sodwana with a couple of clips showing everyday life on the reef. Both these videos were filmed on a beautiful dive on Pinnacles, Two Mile Reef, which was strangely not marred by an absolute circus of an Open Water course that was being conducted in the vicinity. (Pinnacles is a popular training site.) Despite antics which included two people’s weight belts coming loose at the same time, we were able to stay away from that chaos and to enjoy some incredible reef life. (Perhaps I will share some footage of the weight belt fiasco when a suitable amount of time has passed.)

First up, a clown triggerfish (Balistoides conspiccillum) going about his business on the reef. These fish are fantastic looking, and if you ask Sophie nicely, she will show you the hand signal for them, which requires both hands to be free.

[youtube=”https://www.youtube.com/watch?v=QEMgKaVjrKI&w=540″]

Here’s pair of barred filefish (Cantherhines dumerilii) at Pinnacles:

[youtube=”https://www.youtube.com/watch?v=R8hVAL52j0U&w=540″]