Treading Lightly, Sharks in the Rivers

This month’s Naked Oceans podcast delves deep into one of the five major threats the oceans face, and one that has been getting considerable attention lately – overfishing. With the success of the Fish Fight campaign in the UK, which is drawing the public’s attention to fishing discards at sea – it’s estimated that anywhere from 40% to 60% of the total catch in the North Sea is discarded – momentum around the issue of fishery mismanagement is growing.

Naked Oceans looks into the system behind the Marine Stewardship Council certification that helps consumers make sustainable choices in the supermarket, and they examine the factors which make a fishery sustainable in the first place. They also look at a new study that demonstrates just how beneficial MPAs (Marine Protected Areas) can be to the ocean around them, by supplying fish larvae that drift out and can re-seed areas over 100 miles away.

Another recurring theme is the need to provide alternatives to local populations when it comes to making a living from the sea, and this usually means ecotourism. Helen Scales talks with Manta researcher Andrea Marshall about fishing pressures manta populations are facing, the most destructive of which is a growing demand for their gill rakers for use in Chinese traditional medicines, as well as the importance of good site management when it comes to dive tourism.

Meanwhile, in South Africa, Zambezi (bull) sharks have outsmarted a South African Shark Conservancy expedition attempting to tag a few individuals to learn more about what these large sharks are doing in the Breede River, where they are frequently sighted 15km upriver. The researchers hypothesize that the sharks may be pupping in the river, supported by anecdotal reports that a female Zambezi shark was caught more than 40km upriver in 1974, giving birth to six pups when she was landed. Not discouraged by this first attempt, SASC will be trying again in February to tag a few individuals.