Cape Gannets fight over a herring
Over the years, the scientists have noted the sardines are not the only fish to move up the coast. The biomass of herring, particularly the "Red Eye" herring (Etrumeus teres) was astounding in numbers but an abundance of "Big Eye Red Eye" herring (Etrumeus whiteheadi) were very present as well. To top off, mackerel (Scomber japonicus) were also on the table as we found out in July. So really, the name "Sardine Run" is a bit of a misnomer since the presence of at least 5 different species of fish move up with the currents. The sardines, however, are the only fish to hit the beaches of Kwa Zulu Natal, where the netting of Sardinops sagax is a big business. I had daily calls from seine netter friends to find out the movement of the sardines.
Strangely, it is possible due to the abundance of food that for the first time, I did not see the common dolphins (Delphinus Capensis) gather in superpod numbers (thousands). We did have a few pods of 700 or so, but I did not see the big thousand + gatherings nor did I hear anyone else do so. Another missing element was the Cape Fur Seal (Arctocephalus pusillus), which usually pop up north with big storms. Even the number of gannets (Morus capensis) were lower than before. There are reports that the seal, penguin and gannet populations did drop with the unusual weather further south.
Cape Gannet seeking food
I furthered the gannet population decline with the dubious honor of being the first diver on the sardine run to be hit by a diving gannet. I was using a 3 liter pony bottle in shallow water on a very small baitball of maybe 200 E. Whiteheadi. There were only 2-3 gannets diving on the ball with a few dolphins charging infrequently. As I settled in to shoot at about 4m, suddenly armagedon occurred as many gannets suddenly dived on my baitball and created a bubble veil so thick I could not see 2 feet in front of me. The agitation from the birds diving caused the sharks to frenzy and they charged up into the ball from below, bumping my fins and legs while my vision was limited. I turned to face the sharks and had my back to the surface. The silver tank plus the bubbles made it so that even a gannet could not differentiate a tank from a fish until it was too late. I heard and felt a thunk and turned around to see a bird swimming away frantically. I was too busy pushing off sharks to register what happened. It was only afterward when other people noticed a gannet with a broken jaw did it click that was the bird that hit me earlier. Everyone from Thomas Peschak to Jean Tresfon had a pic of the dying gannet. A dubious honor for me indeed!
Black tip shark (C. limbatus) stalks the mackerel. Note how small the 2m shark looks against the big mackerel
Every year, the run surprises with a new development. This year, I saw the biggest baitball of mackerel (Scomber japonicus) ever. I'd seen very small baitballs before and they seemed to be a favorite of the sharks and dolphins due to size. The gannets aren't as big fans as the fish is powerful and big enough that the gannets have difficult catching and swallowing them. I saw gannets hitting the mackerel with deadly accuracy only for the fish to drive out of the beak of the gannet. It's always interesting to see how prey and predator react to each other and the big mackerel baitball showed how much hard work the sharks and gannets have to do and how crucial the common dolphins are in creating a tight baitball so they can feed.
A redeye escapes the clutches of a gannet's beak
Another new observation for myself is the common dolphin's training baitball. We came upon a small baitball were only baby dolphins and their mother would hit. They would back off when divers approached the ball but continue to hit the fish once the diver backs off. This year it seemed the dolphins were really training the young on the run whereas it was only theorized before. I'll continue my observations in part II, which will include a newly observed common dolphin hunting technique (with pics!) and more on the scientific side.
Bottlenose dolphin (T. truncatus) don't maintain the baitball like the Common dolphins do.
As with every year, the movement of bait fish is dependent on the water temperature and currents. This year, netting on the Kwa Zulu Natal coast didn't really happen until late June till mid-July. In fact, sardines were netted all the way past Durban at Umdloti even. So the siene netters had a pretty good year, albeit late and after a lot of thumb twiddling waiting for the fish. Only the Sardinops Sagax hit the shores, whereas the other baitfish seem to stay deeper. Nobody knows why but there's a theory that as the water warms up, the oxygen gets less so the sardines are forced up.
Seine netter Bobby of First Lite Fisheries storms out the river mouth to drop his net
The netting lasted about 1.5 weeks while we had sardine activity for just a few days. So how did the fish past us? They went pass with a cold North bound counter current we discovered one day while diving. This current was 14°C and traveling around 3 knots per hour. Our fish finder sonar found this current carried lots of fish past. The problem was that the common dolphin were not balling as usual. In fact, the number of common dolphins didn't seem that high and many were sub-adults. There was one day where sardines popped up in numbers. Unfortunately we had engine trouble and missed the activity on that day.
This baitball was thick with sharks
So the common dolphins didn't ball up the baitfish but just fed straight as we noticed them doing on numerous occasions this year. The dolphin fed on shad (Pomatomus saltatrix) and even anchovies on occasion. So plentiful were the herring and other baitfish that you'd see them feeding on the surface occasionally. It was also this year that we have to recognize the importance of the common dolphins in this entire food chain. Gannets would not dive in on the baitfish feeding at the surface without the dolphins (I've always called them the blondes of the sea, with their yellow head and blue eyes.) Or are they so in tune in this symbiotic relationship, many don't react to bait fish just meters away from them. Many times, they wait for the dolphins to come round to ball up the fish or they won't move.
The Common Dolphin (Delphinus Capensis) is an integral part of the food chain on the east coast of south africa.
When the commons did start a baitball, quite a few were gobbled up by the hungry Bryde's whales whose mouths just inhale small baitballs, infuriating all the other predators, including the humans who want to dive the balls. So disruptive were the Bryde's (they stamped out 6 baitballs on my count alone), there were curses of calling the Japanese to cull them. I sorta feel for the commons, who work very hard on balling up the fish only for some big mouth cousin to come and gobble it up.
The 'pesky' Bryde's Whale made things difficult for the spectators to enjoy the medium to small baitball spectacles
Not that I was complaining about their presence as such 
As mentioned in Part 1, I photographed a newly observed hunting behavior exhibited by the common dolphins. Over the years, most of the red eye baitballs I'd been on have been Etrumeus Teres or East Coast Herring. This year, the biomass of Etrumeus Whiteheadi or West Coast Herring was impressive. We had 3 baitballs of these fish and this was when I noticed a different attack strategy by the commons. In redeye baitballs, because they tend to pack looser than sardines or mackerel, the dolphins would bubble net and charge through on the outside if the ball was big enough, otherwise they'd just attack in groups and try to single out the fish.
I did a 'dirty' count of all the baitballs (on video) I'd been in over the years and the dolphins were hitting maybe 40-50% on sardine baitballs and 30ish% on red eye baitballs.
A common dolphins picks off a mackerel on the outside of the ball to preserve it
Anybody who's seen the hundreds of hours of clips online/TV/film has seen how the commons always hit the outside of a sardine baitball to keep it intact. They charge through the loosely packed red eye baitballs or generally any balls which are small. However, I found on at least 3 different baitballs, they act as 2 separate groups whereby 1 group will charge from the bottom while another group leaps out of the water over the prey to attack from above. Baitfish tend to run to cover (hence it's not a good idea to be over a baitball lest they seek you out as cover and a predator charges through!), so are these dolphins creating a shadow to trick the prey? I can't say for certain since I only have 3 sequences when I finally realized what was happening underwater (you know, watching for behavior while looking out for sharks, photo op, depth, housing issues in cool waters isn't easy, unless you are Doug Perrine!
)
Here you see how the dolphins are out of the water in 2 separate groups
As they enter into the water, they also try to pick off a stray fish
The action from topside
The other newish thing was the mackerel baitball we had near the end of the season. This was by far the biggest mackerel baitball anyone has seen in a long time. We had smaller pockets over the years but nothing like this. These fish were big, averaging around 20-25cm in length, thus making the predators look like little puppies. In fact, the usually accurate gannets had difficult holding on to the fish as they were powerful enough to escape their clutches. I saw many mackerel slip away from gannet's beaks through sheer power and speed.
This dolphin is 2m long yet looks like a sub adult because of the size of the mackerel
This particular baitball is of interest to scientists because it's been observed through stomach content analysis of common dolphins caught in the nets in KZN (under 10 a year!) that the diet has changed over the last 8 years from sardines to mackerel. This coincides with the apparent decline of sardine numbers overall in South Africa. The mackerel has similar energy to sardines in energy (fat) content, while the other fish aren't as high. Observing how well the sharks and dolphins hunted the mackerel, I could buy into the new theory. The gannets, however, aren't big enough to be as successful as with sardines and herring. This particular baitball lasted over 5 hours and we drifted with it for over 10km until the visibility went to crap. It's not all fun and games and I was aching the next day(or maybe it was the rugby!)
This big 2.5m Copper shark (C. Brachyurus) readies to strike the yummy mackerel.
The decline of sardine numbers have been attributed to over fishing in the Southern ocean of South Africa. Apparently the Western Cape sardine fishery has collapsed and now all the boats from the Western Cape has converged on the Eastern portion, where the sardine population which moves up the coast come from. With no real industry for herring and mackerel and no real data on the biomass available on the numbers of these other fish, it is suffice to say South Africa is facing the same problems the EU, North America and pretty much every part of the world are... the plundering of fish stocks! It may not be long before the South Africans follow the US folly of wiping out their sardine stock (and it still hasn't recovered!)
Will the predators be fighting for scraps while the big fishing boats wipe out stock?
Hopefully, with the scientific interest in this phenomena growing, due to the increase in tourism and awareness, there may be a way to avoid mistakes other countries have made in the past. Otherwise, we'll just have images to show our grand kids of what a spectacle the Eastern Cape of South Africa had.
I'll end off with a note about a few of the dive operators. This year, I saw more snorkelers than ever before, which in itself is already problematic as the snorkelers interfere with the gannets diving into the baitballs (more precisely the medium and small ones) and the sheer number of them also put off the other predators, especially when the baitball is small. Viewing the predation is probably the most spectacular sight there is but to interfere to the bait of inhibiting the predators from feeding isn't a good thing.
This gannet just swallowed a red eye herring and is looking for more!
A C. Brachyurus snaps up a mackerel
Baitfish tend to seek cover and snorkelers create just such cover with their shadow. So with the bait fish under them, the gannets can't dive. The operators who drop their snorkelers in do it because the visibility was so bad that scuba wasn't safe! They tend to pack their boats with up to 10 people so it becomes a mess of people:
Snorkelers crowd a baitball and basically destroy the predation by impeding predators.
Sharks also back off on smallish activity because of the scuba noise. HOWEVER, they will charge when there is disturbance at the surface... oh such as a splashing snorkeler with bait fish huddling under his/her belly. With bad visibility, a snorkeler won't be able to see the shark until it's really close:
Speaking with a few people from the other boats, briefings were abrupt and sometimes non-existent! Then you add safety policies of 5m visibility being conveniently forgotten when action is slow and conditions bad and it turns into an accident waiting to happen. It's sad but customer happiness does become more important than customer safety. It's already a very dangerous activity due to the proximity to hundreds of feeding sharks. Obviously humans aren't on the menu, but frenzied sharks charge and challenge (I was bumped silly on 2 baitballs, including one where I got a BIG clump on the head by a shark that I heard ringing for a minute!) So it's not an activity like a calm shark chum/feed. Then again it is nature at its most raw... well when it does happen.
There have been at least 3 serious injuries by shark encounters over the years, all in poor visibility. The first victim, Tony White, happened in 2002. He was snorkeling in dirty water when his right arm was bitten by a shark. I hope never to see that happen again but I fear with the inexperience and desperation of these operators to put the clients on baitballs to keep customers happy, often in very bad conditions, will drive the lack of safety protocols. Even attire was not properly managed (many divers were wearing bright yellow contrasty suits and fins). I don't wish to be Cassandrian but it's a matter of time before another serious injury occurs if things remain unchanged. So those wanting to do this trip, caveat emptor!
Gannets are amazing in their ability to dive down to 20m, snap up and swallow a fish or 2 before
using their buoyancy to surface.
There's a teaser video here.
