I am short of time today so I will be brief and to the point. Sunday looks like the best option for diving, and Hout Bay looks like the best location. Text or email me if you are keen to dive.
View towards Misty Cliffs from Scarborough Beach
Good news
Reports are that the sevengill cowsharks at Millers Point have cautiously reappeared – I think they’ve possibly been absent since March! We look forward to verifying the reports when False Bay’s visibility is a bit cleaner.
Sunday: Early morning double tank dive, location to be confirmed
Conditions last weekend were pretty good. Not much wind or swell and decent visibility. The wind and swell for the weekend ahead look great with very little of either. False Bay, on the other hand, looks a little messy from some humping south easterly wind today.
False Bay this morning
The wind dies tomorrow and stays away for the weekend. I don’t doubt that both False Bay and the Atlantic will offer decent diving if you take the time to check before you choose. I plan to launch on Sunday as early as possible for a double tank dive somewhere clean. I have family arriving at midday from abroad and want to be done by then. If you are up for a early dive let me know and I will add you to the list.
Great news
The Shark Spotters mobile app is available – search for Shark Spotters in the Apple app store or Google Play store and download it for free!
I completed the edX-hosted Sharks! MOOC, presented by Cornell University and the University of Queensland, and it was excellent. The content was clear and for me, who stupidly quit high school biology at the age of 14 for the sake of a more classical (less useful) education, filled in a large number of gaps in my understanding of sharks and rays.
I’m going to link to some of the most interesting videos below, so you can get a taster of what the course was like. Please sign up next time it gets offered, if you didn’t do so this time!
Broadnose sevengill cowshark at Shark Alley
Week 1: The Big Shark Picture – Biodiversity and Evolution
Staying with our informal theme of the last few weeks’ (admittedly sporadic) posts, let’s look at a recent article from the New York Times Magazine. Not solely focused on marine animal studies, the article explains how technology has enabled even the general public to directly observe and learn about the migrations of birds, sharks and other animals. The utility of this kind of information is obvious:
By discovering the precise routes animals take during migration, scientists can assess the threats they face, like environments altered by habitat loss and overhunting.
A white shark with a satellite tag
The article’s author is brilliant nature writer Helen MacDonald, who wrote H is for Hawk, and she goes on to muse about the meaning of the relatively few individually tagged and named animals which become icons of their species as they appear to transverse a simplified, borderless planet in solitude. (The OCEARCH sharks on their satellite map refer!) It is easy to lose sight of the rigours of the environments they move through, but easy to become invested in the future of particular individuals.
Did you pick up the July edition of National Geographic to read about great white sharks, or read the article online? (Pro tip: you should.)
The article’s author, science writer Erik Vance, contributes to a blog that I follow called The Last Word on Nothing. I was delighted to read a follow-up he posted to his National Geographic feature, explaining how scientists count sharks. At the heart of the method is a beautiful piece of statistics (a model) that allows scientists to draw conclusions about the size of a population – some of whom are tagged or marked – based on only a sample of the individuals, and what proportion of those sampled individuals is tagged.
A dorsal fin breaks the surface
Why is it important to know how many great white sharks (or cowsharks, or whale sharks, or or or…) there are? The most obvious answer relates to conservation: if we have a baseline population estimate, we can then determine whether it is increasing or decreasing over time. What is the status of the population? Are these animals endangered, or flourishing? Are conservation measures necessary? Are they effective?
Go and read about counting sharks here. An important thing to pay attention to when you are reading any scientific model is what the underlying assumptions are, because they will show you the circumstances under which the model will fail.
Shark Spotters have been keeping bathers and surfers safe, and providing groundbreaking research on Cape Town’s white sharks, for over 10 years. They are currently developing a smartphone app that will provide information on sightings of sharks and other marine life, sea conditions, and other information pertinent to the Shark Spotters program.
Sunday: Boat dives from Simon’s Town jetty at 10.00 to the wreck of the Brunswick and 12.30, site to be determined on the day
Liam and Christo near the Brunswick
The cold front seems to have passed by and the second one that was meant to arrive tomorrow seems now to be giving us a miss. We had 40 mm of rain at home on Thursday, for which we are grateful. The break in the weather means there is a good chance some diving might happen this weekend!
I am going to shore dive on Saturday at Long Beach and launch on Sunday, the first dive being to the Brunswick, meeting on the jetty in Simon’s Town at 10.00am. The second dive will be at 12.30, the location weather and viz dependent.
If you want to dive, let me know!
Support Shark Spotters
Don’t forget to donate to help the Shark Spotters complete their beach info smartphone app! Also, there’s an auction and comedy evening (with Nik Rabinowitz!) at the Two Oceans Aquarium on Wednesday 27 July, also in aid of Shark Spotters’ research. There’s more information about the event here.
I know we are barely past the halfway mark of winter, but the last few warm and pleasant days have got me wishing summer was here.
Some swell and lots of south easterly wind are in the forecast for Saturday, so Sunday will be the better option for diving. We will aim for a later start to see how well False Bay fares during Saturday’s onslaught. If we decide to launch the boat it will be from the Simon’s Town Jetty at 9.30 and 12.00 and the most likely sites will be Photographer’s Reef and Roman Rock.
If the conditions aren’t boat-worthy on Sunday, we’ll shore dive at Long Beach.
An app for beach lovers
The Shark Spotters centre at Muizenberg
Shark Spotters, who do pioneering beach safety work and shark research in Cape Town, are crowdfunding a mobile app which will provide information on beach and surf conditions, shark and other marine animal sightings, and whether the Fish Hoek exclusion net is currently deployed. The app will be available free of charge. Watch this video for more information about the app, and give your support by donating here!
We went out hunting for cowsharks (they’re still AWOL) and visited the seals this afternoon. The visibility is not great, about 4-5 metres at Patridge Point and about 3 metres at Shark Alley.
Afternoon rays at Millers Point
This weekend we will launch the boat for dives on Sunday, should the swell permit. It’s not a very large swell, but the period is long which could make diving uncomfortable. Let me know if you’d like to be on board and I’ll keep you posted.
