Blue Sharks Out In The Deep

Majestic blue sharks off Cape Point. Photo Morne’ Hardenberg

Tuna fishermen have been reporting loads of blue sharks (Prionace glauca) off Cape Point, South Africa. Morne’ on behalf of the SOSSC and Shark Spotters went to investigate and dive with these cobalt-blue sharks. What he saw both mesmerized and disgusted him. Photo credits: Morne’ Hardenberg

Warm 20 ºC water, 10 meter visibility and loads of blue sharks – this is something every shark diving enthusiast will take advantage of given half the chance. Five am on Sunday morning Morne’ headed off (I stayed behind to catch up on office work) and after a 2 hour long boat trip they reached the point were the water is good for yellowfin and longfin tuna – and sharks! Pretty soon the giant yellowfin tuna were circling and the first sharks appeared. Morne’ quickly hopped in the water with camera in hand. This was his second blue shark diving experience, the first being while diving under a whale carcass a few years back with a single small animal, and he was amazed at the beauty of these sharks. Cobalt blue and silver bodies diving around him gave the feeling that he was in a fantasy world for sharks!

Unfortunately, after these first majestic encounters a 1.5 meter blue shark came swimming up to him and as it got closer Morne’ saw that it had a severe wound around its gills. Upon closer inspection he saw what looked to be fishing line wrapped around the shark’s gills which was cutting deep into the flesh. This particular shark stayed with Morne’ for half an hour and Morne’ was able to film and photograph the shark. What more than likely happened in this case was that a blue shark was caught on a fishing line and while being reeled in probably twisted around trying to free itself. The line was either cut or the shark broke free, but the fishing line was left wrapped tightly around the animal’s body. This monofilament line is very strong and not flexible and as the shark grows it slices through the skin. In all likelihood this shark will die a slow and painful death as it continues to grow.

Many sharks are caught as bycatch while targeting tuna and responsible fishing guidelines encourage anglers to cutthe line as close to the hook as possible to prevent this kind of entanglement. The hooks themselves will eventually rust away.

Blue sharks are the most heavily fished sharks in the world mainly as result of by-catch and are listed as Near Threatened on the IUCN Red List of Threatened Species. For more about blue sharks visit:http://www.iucnredlist.org/details/39381