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Chokka Squid and Their Predators




Squid, Loligo Vulgaris reynaudii, spawn in the inshore areas of the Eastern Cape throughout the year, with this activity peaking in November and December. A good area to dive with the squid is in St Francis Bay during the closed fishing season in November. Conveniently, the egg beds are often found in the Bay within a few kilometres of the small boat harbour of Port St Francis. During this time the harbour is full of squid fishing boats, laid up for repairs.

The biggest challenge, from a filming point of view, is the underwater visibility that can remain poor, especially near the seabed, for days on end. The squid activity is also affected by underwater visibility, water temperature and the time of the day (sunlight penetration). The optimum water temperature for spawning is between 16 and 18 degrees C at the bottom, but the bottom water temperature can drop to as low as 8 degrees C in the area.

The squid mate in the water column above the seabed and spawn predominantly on sandy substrata. The resulting egg beds may cover large areas of seabed. The pale orange egg clusters gently waving in the surge, with thousands of squid moving from their mating depth to the egg beds to spawn, make a spectacular sight.

A large range of predators take advantage of the high squid biomass during the peak spawning period. The most common are short-tail stingrays, diamond rays, spotted ragged tooth sharks (sand tigers), smooth-hound sharks, Cape fur seals, cat sharks and fish. Unlike the other predators, the cat sharks are only found on or near rocky substrata and therefore normally only predate on squid near such areas.

Of these predators, by far the most common on the St Francis Bay site was the short-tail stingray. From above, the orange egg clusters stand out against the white sand. Rays can be seen everywhere, swooping over the egg beds, scattering the squid. On the outskirts, the smooth hound sharks patrol, probably keeping their distance from the divers and their noisy bubbles. Up in the warmer water, juvenile dusky sharks are often seen. During a single dive it is not uncommon to see five different ray species.

The seals rely on the speed, agility and intelligence of a marine mammal. While rays or sharks swimming over the egg beds, cause minimal disturbance to the egg laying, a seal swooping down on the beds will instantly clear the area of squid for at least a minute. Seals floating on the surface often indicate the presence of squid below. Once a seal captures a squid, it returns to the surface where it smashes the squid on the water surface to break it up. During this exercise the awaiting sea gulls sometimes get lucky and snatch the squid from the seal.

Cannibalism is fairly common amongst squid. Sometimes a squid can be seen with another squid in its mouth. Sometimes two or more squid, tentacles locked, engage in a tug-of-war over a dead squid.

While challenging, both because the action is fast and unpredictable and the water clarity is often poor, the results of filming this amazing natural occurrence is undoubtedly worth the effort. While it may lack the adrenaline rush of the sardine run, the squid run projects a certain appealing complexity and elegance.

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