White steenbras on the Clan Stuart

Sea life: White steenbras

Among my favourite friends at the Two Oceans Aquarium in Cape Town are the white steenbras or pignose grunter (Lithognathus lithognathus) that live in the Kelp Forest exhibit. They seem to prefer one particular window, and every time I pass by they are gathered there, bumping gently against the glass when I raise my hands to greet them. The literature about the exhibit indicates that it’s extremely rare to see such large specimens in the wild, as white steenbras have been under signifcant fishing pressure for decades.

Today they are reserved for recreational fishermen, and are a very sought after fish (which has led to gross overfishing). They can grow up to 1 metre in length and weigh up to 30 kilograms. They’re fairly solitary fish, but during certain times of the year (such as summer in the south Western Cape) they aggregate into schools. They have seven dark vertical bars on their silver bodies, thick lips and small mouths. They typically feed on white mussels, crabs, sand prawns, and worms. They are endemic to South Africa.

White steenbras spawn in estuaries along the eastern Cape coast, and mass spawning migrations to these areas occur in autumn (March-May). This preference for estuarine spawning (juveniles actually spend up to two years in nearly fresh water before coming out to sea) makes them extremely sensitive to degradation of their spawning locations. Estuaries in Southern Africa have never been well managed.

White steenbras on the Clan Stuart
White steenbras on the Clan Stuart

My first (and so far only) encounter with a school of white steenbras – or indeed, any white steenbras at all – was during a dive on the wreck of the Clan Stuart on new year’s day. We were a fairly large group – seven in total. Fishermen were active on the beach in front of the wreck, so we took care to avoid their lines as we went in. The visibility was maybe three metres, and seconds after reaching the wreck we were surrounded by a large school of very twitchy, good-sized steenbras. They swam around and around us, changing direction at random, and then disappeared. A few minutes later they found us again, and repeated the same agitated behaviour.

From the first moment we encountered them, Tony, Laurence and I (we would later discover) all began to feel incredibly uncomfortable. The fish were behaving as if something was chasing them, and they seemed to be trying to use us as cover. What could be chasing a steenbras? These are large, confident fish.

White steenbras on the Clan Stuart
White steenbras on the Clan Stuart

The feeling of discomfort and anxiety continued for the rest of the dive. Laurence (lost the group and didn’t like the idea of being in the water alone, with poor visiblity and a large predator on the prowl) and two of the other divers (equalisation problems) aborted the dive early, leaving me, Tony and his two students – both tourists – to explore the wreck a little and make our way back to shore. It was probably one of the three least enjoyable dives I’ve ever done.

We’re fairly sure that a great white shark was hunting in the vicinity, spooking the fish. The concern was not so much that it would try to target the divers, but that we’d get in between it and its prey (as happened to Lloyd Skinner), and meet with misfortune that way. I was also concerned about getting munched because that very morning I’d given a sleepy interview on Radio 702 about sharks in False Bay, from the perspective of small business owners. It would be embarrassing to state that sharks don’t explicitly target humans in the water as prey, and then get eaten by one.

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Clare

Lapsed mathematician, creator of order, formulator of hypotheses. Lover of the ocean, being outdoors, the bush, reading, photography, travelling (especially in Africa) and road trips.

2 thoughts on “Sea life: White steenbras”

    1. We were lucky – I think it was feeding time when we arrived or something, and the divemaster had a little bag of squid and stuff. He let me give it to them – was amazing! Even had finger munched.

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