The sardines may arrive a little late off KwaZulu-Natal this year, the KwaZulu-Natal Sharks Board said on Thursday.
"The water temperatures are still fairly high, which is not good for them," said the board's head of operations Mike Anderson-Reade.
"It is too warm and early at this stage, even though there were quite a few years where they came very early."
Anderson-Reade flew out to sea last Friday to check for sardine activity but there was none.
"There was a bit of activity, south of Port St Johns... but it was not the sardines."
He plans to do another flight, possibly next Thursday if the weather is good, to check for sardine activity.
The sardine arrival was expected in KwaZulu-Natal in the first or second week of June.
In 2010, the sardine run began in mid-July and resulted in bathing being banned for almost a month, due to predators, such as sharks, feeding.
The sardine migration occurs from May to July when billions of sardines spawn in cool waters and move along the country's east coastline.
Their numbers create a feeding frenzy and shoals are often about 7km long, 1.5km wide and 30 metres deep. They are visible from spotter planes or the surface.
Sardines are followed by many predators, including Cape gannets, sharks, and dolphins.
The annual Sardine Run is a popular event and KwaZulu-Natal residents and international tourists eagerly await it every year.
Scores of documentary makers and tourists book into chalets along the south coast waiting to get a glimpse.
In recent years, the fish have been netted and no shoal has beached.
Decades ago, families in Durban would gather on beachfronts in June and July waiting for the slippery delicacy to reach the shore.
And when it did, parents and children, armed with baskets and crates, would hastily pack their baskets and head home for a fresh tasty meal.
In the Indian community, masala-marinated sardines are favourites.
Hawkers and traders, who make a living off the catch, also wait anxiously for the shoal every year.