THE GREAT­EST SHOAL ON EARTH

Scuba Diver Ocean Planet - - One Ocean - Text by Sophia Van Coller, as told by Mark Van Coller

A fu­ri­ous, fren­zied, un­der­wa­ter cir­cus awaits in­trepid divers who ven­ture south for South Africa’s cel­e­brated sar­dine run

“Death comes from all sides; from the sky, thou­sands of gan­nets dive into the school while the dol­phins charge from the left, from the right, from be­neath. Hun­dreds of bronze whalers, dusky and sand tiger sharks pa­trol the lower and outer realm, mak­ing oc­ca­sional for­ays through the cen­tre of the fish ball. Lurk­ing below, un­seen in the dark­ness of depths, five, 16-me­tre, 50 ton hot­blooded preda­tors rise up­wards or side­ways through the sil­very shoal. Some sar­dines es­cape the whale’s charge by hurl­ing them­selves into the air, but their re­prieve is but mo­men­tary as hun­dreds of preda­tors are wait­ing to pounce on the es­capees.” – Michael Aw, Ex­plorer

The sar­dine run hap­pens in the win­ter months from May to Au­gust, when mil­lions of sar­dines, Sardinops sagax, leave the south­ern Cape wa­ters of the Agul­has bank, to fol­low the cold, nu­tri­ent-rich body of wa­ter up the African coast to Kwazulu Na­tal. This belt of cold wa­ter in which the sar­dines travel is formed by the win­ter storms of the Cape, push­ing the cold wa­ter north, while the warm Agul­has cur­rent that runs from the north to the south traps this cold wa­ter against the coast. Along the Transkei coast, the con­ti­nen­tal shelf pushes this cold wa­ter into its nar­row­est strip, con­cen­trat­ing the sar­dines and the preda­tor load at its high­est, cre­at­ing the con­di­tions for some high-oc­tane ac­tion. Film crews, am­a­teur pho­tog­ra­phers, and ocean en­thu­si­asts all flock to Port St. Johns, Mbo­tyi and the sur­round­ing ar­eas to get a space on the char­ter boats that pro­vide the best op­por­tu­nity for wit­ness­ing this event.

Port St. Johns is a small, rus­tic town on the Wild Coast, a 250-kilo­me­tre stretch of coast­line which gained its name from its inac­ces­si­bil­ity and treach­er­ous shore­line. Al­though this makes for risky surf launches on the semi rigid in­flat­a­bles, and hair-rais­ing ad­ven­tures at the crack of dawn with high-end cam­era equip­ment, it makes it all worth­while when your skip­per drops you right in the middle of a feed­ing frenzy. From the skies to the depths below, preda­tors line up to feast on the protein­rich bait­fish.

SCHOOL­ING TO SUR­VIVE

Th­ese bait balls form when com­mon dol­phins sep­a­rate a small pocket of fish from the main shoal, and push it up to the sur­face. The dol­phins cir­cle the bait ball for a while, blow­ing bub­bles from below, herd­ing the lit­tle fish into a tight swirling mass. They then dart through to­gether in a group to grab as many fish as they can. They will re­peat this pat­tern over and over, un­til the last sar­dine is gone. Th­ese sar­dines know, if they lose the group, they are an easy tar­get.

The sharks on the other hand, have no such skilled and or­gan­ised feed­ing plan in place. Their strat­egy is to sim­ply swim through the bait ball, mouth agape, con­sum­ing as many mouth­fuls of fish as they can. That is why we, as divers, never hang around in­side the bait ball! Some­times that proves dif­fi­cult, as the sar­dines of­ten try to use divers as pro­tec­tion.

BAT­TERED FROM ABOVE

Once the bait ball is vis­i­ble to the birds in the air, Cape gan­nets bom­bard it from ev­ery an­gle, rain­ing down like bul­lets. When each gan­net hits the wa­ter, it’s like an ex­plo­sion below the sur­face, and one of my favourite mo­ments of the sar­dine run. Th­ese gan­nets, with their wings folded back, tight as tor­pe­does, can eas­ily dive to a depth of 15 me­tres to reach the bait ball, and some­times grab up to three fish, be­fore re­turn­ing to the sur­face. Gan­nets have been recorded hit­ting the wa­ter at more than 85 kilo­me­tres an hour, which has of­ten made me won­der: should I be div­ing with a hel­met…? My most mem­o­rable gan­net pic­ture was taken at the end of a long day at sea. We had less than five min­utes left in wa­ter, be­fore our skip­per was go­ing to pull us out be­cause it is un­safe to go back through the break­ers in the dark and the light was fad­ing. The evening light had turned to a mag­i­cal golden glow and the shal­low bait ball was mov­ing slowly in the shim­mer­ing light. I was wait­ing pa­tiently for some­thing to hap­pen, when sud­denly a gan­net hit the wa­ter right in front of me and opened its wings as he grabbed a fish out of the flee­ing shoal. I knew I had cap­tured some­thing spe­cial.

IT’S A WHALE OF A TIME

Hump­back whales are of­ten seen in the area, cruis­ing along on the sur­face in fam­ily groups. They are in fact

not here for the sar­dines, but are mi­grat­ing north­wards to the warm Mozam­bique and Mada­gas­can wa­ters to have their calves. This makes for an added bonus, when search­ing the open ocean for any bait ball ac­tion. How­ever, a whale that is def­i­nitely there for the sar­dines is the sel­dom-spot­ted Bryde’s whale, the largest of the sar­dine run preda­tors. In 2010 I was lucky enough to come face to face with one of th­ese mag­nif­i­cent an­i­mals, while film­ing one of the largest bait balls I’ve ever seen. I was about eight me­tres un­der­wa­ter, when sud­denly the bait ball parted and, head­ing di­rectly for me, was a 12-me­tre Bryde’s whale. I had to make a move, be­cause he had no in­ten­tion of avoid­ing me. He barely missed me as I moved up­wards, pulling my fins in tightly un­der­neath me. What a spec­tac­u­lar sight it was later in the day, when I man­aged to film him, lung­ing through the bait ball from below. Be­ing sur­rounded by masses of sharks, huge pods of dol­phins, whales, game fish and thou­sands of seabirds, all feed­ing off the gi­ant shoals, is surely an ex­pe­ri­ence ev­ery diver hopes for. We all dream of that per­fect bait ball in clear blue wa­ter, with end­less ac­tion; a vi­sion that keeps us com­ing back year af­ter year. SDOP

1. A com­mon dol­phin snatches a strug­gling sar­dine from a small shoal that they have chased up to the sur­face, in the fad­ing evening light off Port St. Johns Im­age © Mark Van Coller

2. A large pod of bot­tlenose dol­phins hav­ing fun in the large break­ing waves, as they make their way north­wards up the coast Im­age © Mark Van Coller

3. Two hump­back whales, mi­grat­ing up the coast from the South­ern Oceans, to the warmer Mozam­bi­can wa­ters. They are not here to feed on the sar­dines but just hap­pen to co­in­cide with the sar­dine run, when do­ing their an­nual mi­gra­tion Im­age © Mark Van Coller

5. A Cape gan­net dives into a small school of sar­dines, as the last rays of sun­light hit the wa­ter Im­age © Mark Van Coller

5. A shark dashes through a gi­ant bait­ball to get a mouth­ful of sar­dines, one of the many preda­tors at­tack­ing this shoal from all sides Im­age © Mark Van Coller

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