Surfing Sardines! By Kevin Tuohy

Surfing Sardines! By Kevin Tuohy: I think an important discussion to have is how wind and swell direction affects the movement of the sardines towards KZN during the annual sardine run.

The anatomy of a wave and how they form and what causes them to become larger swells such as we get off the east coast of South Africa every year. Waves are generated by wind.

Wind over the surface of a body of water causes little ripples and those ripples join together. Eventually they catch up to each other if that makes sense and they become like a little wave. And then if the wind strengthens those little waves catch up to each other and they become bigger waves and so on and so forth. And eventually we end up with swell. And the swell moves in the direction of the wind that generated it. So that’s a very simplistic anatomy of the wave but that is what we call wave dynamics. The other important thing to understand is that waves work in a circular motion. So water rushes up the face of a wave. As the wave approaches the water in front of it, it pulls that water up the face in a circular motion. And the higher up the swell that circle goes, it changes direction basically. goes, it changes direction basically. So it rushes up the wave from north to south and then it crests on the top of the wave and actually the top of the wave is moving in the opposite direction. So that’s basically what a swell is.

And how this affects the sardines is very interesting because if we look at our winter swell that hits Southat our winter swell that hits South Africa, as any surfer will tell you, they wait every year for our south swell, those big south swells that are generated very, very deep in the Atlantic Ocean off of the tip of Africa, and very, very strong storms and violent winds down south. And that creates what we call a groundswell. So a groundswell is a swell that isn’t locally generated. It’s generated in the same manner as localized wind swell, but it comes from much further away. And surfers wait every year, places like Jefferies Bay just turn on in the winter time. And that’s when all the international surf contests are held because of that predominant south swell that moves in. And if we talk about what south swell means, it means that it’s originated in the south and it’s moving from south to north. So it’s moving up the east coast. Now, this is a very important factor when it comes to sardines and the movement of the sardines, because it’s a topic that hasn’t really been discussed much. And all the research that I’m doing, it’s not evident.

And I think what we need to realize is that these south swells coincide with the sardine run.

And I think it’s very evident to me sitting here through my observations that whenever that south swell is running and it’s pushing the sardines up the coast much faster because the movement of the water on the surface is from south to north, which is exactly opposite the current, which is a north to south current. On the surface of the water, the water actually is moving over the top of the current. It’s overriding it. The stronger the south swell, the more movement of the water is going opposite to the direction of the current. So what the sardines are doing is that they’re actually riding these swells. And I see that

that all the time when the South swellers up the sards are on the surface so instinctively they know that and they feel it maybe I don’t know how it actually works but they’re on the surface so these big South swells that’s what’s bringing these sardines to the surface because the deeper they go in the water, the more they’re back in the current. They’re fighting the current. So they take the path of least resistance. They come to the surface and they’re actually surfing the swell. That’s what they’re doing. And as soon as they come to the surface, they then fall prey to all the predators that are there, especially the gannets. And that’s what we see, all the gannets diving. And you would think that the sardines would dive deeper just to get away from the predators, especially the gannets. Well, they don’t. They’re on the surface for a reason. It’s because they’re using that south swell to move up the coast. We don’t know why they’re moving up the coast. That’s been debated for many We just years. know that they are moving up the We don’t coast. know why they’re moving up the That’s coast. been debated for many years. We just know that they are moving up the coast. They are just wanting to get north. No matter what happens, they’re caught in that cold plume, and their migratory instincts are telling them, head north. There is no option to turn around. So it’s a very interesting phenomena that whenever the south swell picks up, the sardines get moving extremely fast and they’re on the surface. So yeah, it’s quite interesting to look at and I can categorically say that this does happen due to my observations here. So I’m waiting for the south swell again. I’m looking out deep and I’m seeing the ships are rocking and rolling out there. There’s a south swell bump on the horizon. And as soon as that moves inshore, the sardines start capitalizing on its movement and they surf it northwards.

By Kevin Tuohy of Wild Coast Cottages.