WATCH: Hammerhead sharks thrive in the Point Waterfront canal

NESTLED along the Point Waterfront canal is a 25m-squared enclosure, currently home to two hammerhead sharks. The canal contains about 50 species of fish that form part of its thriving ecosystem, and the enclosure offers a haven for hammerheads, which are listed as a threatened or protected species.

Hammerheads caught off the coast are brought to the canal as juvenile pups where they can grow in safety before being released. This project began in 2013 when uShaka Sea World was given permission to build the enclosure. Speaking to Berea Mail, Jason Haxton, lead aquarist for large exhibitions at uShaka Sea World, said the hammerheads have thrived in the enclosure after a short stay in the aquarium exhibit.

“The idea was to have an area where we could grow out certain species. We have had striped bonito, dorado and now the hammerhead sharks, which have been here for a couple of years. We find they thrive in this enclosure. We have tried them in our aquarium exhibits, but we find the canal enclosure is a more favourable destination for them. It also offers the public a great opportunity to observe these animals,” he said.

Sharks are sometimes brought to uShaka Sea World when they become tangled up in nets or caught along the coast. They are released once they reach a size where they are less likely to be at risk from other predators.

“We do have them as a grow-out species, so they do not stay here for their full life term. We get them as juvenile pups from SA nets,” said Haxton. “We maintain them, we feed them four times a week, and staff come down to the canal, several times throughout the day, to monitor the sharks. We keep a very close eye on them. With our current permit, we are allowed to keep four at any given time. We currently have two sharks, and we are looking at releasing these two before getting another two in.”

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A hammerhead diet consists of fish and squid, and the uShaka kitchen stocks a range of fish, including sardines, hake, mackerel and yellowtail, to name a few.

While the murky colour of the canal water has raised concerns for some passersby, the thriving fish populations are a testament to the health of the canal.

“The canal itself has 50 species of fish, which is quite a variety of species for the area. We have juvenile blacktails, which have grown out, which is great – it shows you that fish are spawning in the canal and the smaller fish (larvae) are safe. The fish co-exist with the hammerheads. The large, spotted grunter was the first species to be put into the canal, and they have thrived. We have about seven generations of spotted grunter in the canal, which means they have been spawning for seven successions, and there are seven different sizes seen in the canal. That tells you we have a very healthy environment,” said Haxton.

“People have raised concerns about the canal’s water quality, but the proof is in the pudding. With so many generations of at least five different fish, it tells you that we are doing something right at the canal,” he added.

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In a statement, the South African Association for Marine Biological Research (SAAMBR) listed several ways uShaka Marine World has boosted a flourishing ecosystem at the canal: Supplying filtered water at a rate of 250–300m-cubed per hour every hour; daily water-quality checks by their internal microbiology team, and managing the fish within the canal.

Due to its natural state, there are algal blooms from time to time.

“These are not harmful to the inhabitants – it is a natural occurrence due to temperature increases and sunlight. The animals are not impacted by these blooms – if anything, it contributes to higher oxygen levels during the day and often to a higher zooplankton presence,” said SAAMBR.

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