Stunning images open a window on the deep-sea world

Stunning images open a window on the deep-sea world

Stunning images of the fishes and marine life living on or close to the seabed nearly half a kilometer under the sea, have been gathered by University of Cape Town (UCT) scientists working with a submersible camera off the west coast of South Africa.

The scientists collected the images in the first of a series of surveys that will test the environmental impact of  hake trawling in South Africa.

Their investigations are the result of a three-year collaboration between the South African Deep Sea Trawling Industry Association (SADSTIA); UCT; the South African Environmental Observation Network (SAEON) and the Department of Agriculture, Forestry and Fisheries (DAFF).

Chief scientist Colin Attwood of UCT, led a team of scientists and technical specialists that included post doctoral student, Charles von der Meden (SAEON); doctoral students, Karen Tunley and Steward Norman of UCT; Driaan Pretorius, ship manager of Viking Fishing and electronics technician, Xolani Methu (DAFF).

“The water was perfectly clear at a depth of 360 to 510 m,” said Attwood, adding that the remarkable images of hake, jacopever, skates and an unusual type of “spiny eel” were probably the first of their kind ever taken in South Africa.  

To capture the images, the scientists deployed a submersible Ski-Monkey camera mounted on a steel sled. The camera was towed behind the research vessel Ellen Kuzwayo at carefully plotted positions. At each deployment, the camera captured 10 minutes of still photographs and 10 minutes of video footage of the seabed and the organisms living on or just above it.

A Van Veen grab was used to collect samples of the benthic macro-fauna (invertebrates like worms, crustaceans and bivalves that live on or in the sediments).

From March this year, hake trawlers will no longer trawl in the experimental block where the photographs, video images and sediment samples were taken. The 6 x 15 nautical mile block is part of the trawl grounds known as Karbonkel, situated near the edge of the continental shelf off the Northern Cape town of Port Nolloth. 

“The intention is to repeat the survey in subsequent years so that we can determine whether there is a recovery in benthic life,” said Attwood.

“With cooperation from SADSTIA-affiliated trawlers, the closure should provide an excellent test of the ability of the trawl grounds to recover. The surveys will increase our understanding of the biodiversity in this environment, and the effects of depth and trawling–related disturbance.”

The trawling industry is enthusiastically supporting the experiment, with the chairman of SADSTIA, Tim Reddell, saying it is vitally important for the industry to better understand impact that fishing has on the environment.

“The more information we have, the easier it is for SADSTIA to consistently improve the environmental footprint of the fishery,” said Reddell.

“This experiment is just one of the projects that SADSTIA has initiated over the past ten years in an effort to meet and exceed the exacting standards of the Marine Stewardship Council (MSC).

The South African deep-sea trawl fishery was the first hake fishery in the world to be certified by the MSC as a sustainable and well managed fishery. It has retained this prestigious endorsement ever since.

Captions

1. The submersible Sea Monkey camera was deployed from the research vessel, Ellen Kuzwayo. Operating a camera nearly half a kilometre under the sea was not without its challenges. The camera had to be towed sufficiently fast to keep ahead of the plume of dust it raised, and predictably, there were a few failed attempts to get it to move, with the sled digging into the soft sediment and occasionally rolling over. However, in spite of these problems, three hours of video footage and 1928 photographs were taken over the five-day survey.

2. The unmistakable red- orange colouring of a jacopever, captured on camera at a depth of 490m. Jacopever is a common by-catch species of the South African deep-sea trawl fishery and a good eating fish. It was apparently named for a Dutch sailor called Jacob Evertsen who had a ruddy face and big eyes!

3. A shoal of deep-sea spiny eels or spiny back eels Notacanthus sexspinis was captured on film at 474m. Though they look like eels and their common names suggests they are eels, these deep sea fishes are not a member of the eel order (Anguilliformes). Instead, they are members of the order Notacanthiformes. 

4. This species of skate is yet to be positively identified but is thought to belong to the family Rajidae, which consists of nearly 30 different species.

5. The team of scientists and crew who contributed to the success of the research voyage that took place on the Ellen Kuzwayo between 2 to 9 February.

6. A Van Veen grab was used to collect samples of benthic macro-fauna (invertebrates like worms, crustaceans and bivalves that live on or in the sediments).

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