Spinner Sharks! - Observation of the Week, 8/31/21

Our Observation of the Week is this Spinner Shark (Carcharhinus brevipinna), seen off of South Africa by @veld_mens!

A scientific marine and fisheries observer on fish and seismic vessels, Carika van Zyl was on a trawler off the coast of South Africa and tells me 

I was doing data entry on the bridge and a splash caught my eye. I then saw another splash. I grabbed my camera and tried to take some pictures to identify the species. At first I thought it was a dolphin but it soon became apparent that it was a shark. I was completely amazed as I have never encountered [spinner sharks]. There were about four sharks and over a couple of weeks I spent hours photographing them in the afternoon and individually identifying them, trying to look for specific markings and thus realizing that it is the same group following the vessel. It was quite the task as you never knew where they would breach and they would jump so fast that I basically got 100's of splash photos.

One day, I was in luck and with a prayer and a strong resolve, realizing that I had to get good pictures of them. Strangely enough they are predominantly found more inshore and in warm waters. We were about forty miles offshore, and in 1000m deep cold waters…

Having the chance to witness and photograph these sharks in action was truly a highlight for me. They would just give us a show everyday. This trip really cemented my respect for sharks and the need to protect them.

Found in most subtropical waters around the world, spinner sharks swim quickly through schools of small fish such as sardines, spinning all the while, and then breach the surface as you can see in Carika’s excellent photos. As Carika noted, they’re normally found in waters shallower than 350 feet or so but she explains that “during [the trip] there was a huge change in ocean temperature, due to currents, which affected much of the East and South Coast and I think that was why they were so deep.” These sharks grow to a maximum length of about three meters, or just under ten feet.

Growing up in Ceres, South Africa, Carika (above) “fell in love with the mountains, its leopards, baboons, the fynbos and the historic bushmen rock paintings” of her home and earned a masters degree in Marine Monitoring, leading to her current occupation. She uses iNaturalist “mostly to assist in identifying fynbos species, and I so appreciate all the kind people who [help me].”

- Here’s some footage of spinner sharks off of Florida. 

- And don’t forget their look-alikes, the spinner dolphins! David Attenborough narrates a video featuring them here.

Publicado el 31 de agosto de 2021 a las 10:44 PM por tiwane