Day two – the double cold front hits the Wild Coast

This morning we woke up to clear skies full of bright stars winkling through the skylight of our woody accomodation. Things were looking good, but we knew there was trouble brewing; 35 knots and 8 m worth of trouble. There was no time to lose – we packed up the boat, got it in the water and cast off from land. The cruise down the 2 km long, stunningly beautiful Mzimvubu estuary was our welcome back to the sardine run from the very sea itself. The launch was fairly calm and we were out across the surf in no time. Rod Haestier has years of experience of launching through surf, so it was with extreme confidence that we headed out onto the big bad sea.

gannets diving onto sardine

It didn’t take us long to find the action – the feeding activity was in the same vicinity as yesterday – directly off Port St Johns, between the Mzimvubu River and 2nd Beach. There was some great activity with gannet volcanoes of about 200 – 500 birds diving chaotically into a cauldron of bubbles, scales and dolphins, all of this spread out in large patches. The water was fairly clean further OS, but the activity was moving too fast to get in. There must have been about 2000 – 3000 gannets in the area.

 

 

 

and now the west is humping

Then the west really picked up – the beginning of the double front, and we beat a retreat for the Mzimvubu. The gannets were observed feeding in SW winds of up to about 18 knots. Above 18 knots they were circling more than feeding. Strong winds must substantially increase the risk of making an error diving, and don’t forget, when you’re a living arrow firing yourself towards the water, you want to make sure that all systems are 100 % go. By 8.00 am the west was pumping at 25 knots and we decided to call it a day. The 15 minute drudge back to the sanctuary of the estuary was one long, chilly splash.

 

 

and now the wind is really humping

 

 

 

 

 

 

 

Back on land, and after a shower, we had a cup of Joy Haestier’s fine coffee, and then helped Rod level his slip way with a load of river stone.

delivering the stone

In the first photo you can see the stone delivery men unloading the truck, and in the second, you can see Rod admiring the handiwork. What there is no picture of, is us getting stuck in with the shovels. Yes, we did. Shovelling stone is not unheard of during the sardine run. Most stone shovelling is done during double cold fronts when one has to work off the extra kilo joules packed on during feasting upon Joy’s wonderful home cooking. A few more days of staying at The Creek and we may well turn into land whales! Tonight was mutton curry. guuurrrrr!

 

 

 

 

Rod admiring our handiwork

 

 

 

 

 

 

 

 

sea surface temperature 22 nd June

Ok, enough of us. Have a look at the sea surface temperature satellite image for the 22nd June. Look at that nice cold strip of water heading all the way up the east coast to the Coffee Bay region. That water is NICE AND COLD!!! If there is still going to a sardine surge up the coast this year, then now is the time. Look out for solid sardine activity heading up the Wild Coast in the next week or so.

Day one of our run

So this morning, knowing that a vicious double cold front was barreling its way up the east coast, we loaded up Rod Haestier’s 21′ ski-boat and set it into the Mzimvubu Estuary. All was going well until we felt the first puff of westerly wind. That puff quickly turned into a buster signalling the end of the day’s festivities. Disconsolately we trudged back to Rod’s guest house, knowing that our first day on the water was to be aborted before it had even begun. The double front, with swells of 6 m predicted, means that we’ll be off the water for at least 3 days.

During breakfast the rain arrived. A short, sharp shower, and we were very smug; happy to be inside scoffing our breakfast knowing that it was no use being out on the water in the face of a double front. But what? 30 minutes later the sun was out and the west was gone. We headed up to the viewpoint at Port ST Johns…

watching sardine run activity

Off The Gap there was some good predator feeding activity with about 2000 gannets and common dolphins feeding together, and at least 12 boats in attendance. Whilst we were watching, a pod of over 300 bottlenose dolphins swam northwards along the cliffs below us. Vic was of the impression that this was a pod of the migrant stock, discussed in one of our earlier blogs. Their proximity to the sardine run activity and the size of the pod certainly provide evidence for this.

It was frustrating looking at all this activity in nice sunny conditions with a light offshore blowing. What had appeared to be a vicious cold front was probably a small coastal low that passed through Port ST Johns in the morning, and that we mistook it for the approaching double front (which is now thundering through Port St Johns as I type). We did try to get the boat back in the water, but by this stage the estuarine tide was too low, and there was no way to launch. C’est la vie, and if you’ve got no patience, you’d better not bother waiting to film sardines on the run.

Later we drove back up to The Gap and watched the birds feeding in the now strong westerly wind – at least 12 knots. There was still a lot of activity and we wondered whether they were feeding in desperation, knowing that severe weather was headed their way, with little chance for successful feeding in the days to come. That’s an hypothesis that would be difficult to test scientifically.

What does one do when one finds oneself at Second Beach, Port St Johns on a beautiful sunny day with no sardines to photograph? Why, one photographs cows, of course! All photos are courtesy of Justin Gilligan.

 

 

 

 

 

 

The Run is On!

Well, it’s great to see that the sardine run has reached the KZN coastline. Yesterday the sardines were as far north as Hibberdene. Thus far, there has been limited activity, but a perusal of the latest satellite image is very encouraging:

sea surface temperature satellite image for the 19th June

On his June 17th twitter broadcast, Barry Skinstad suggested that the predicted three days of NE winds would help cool nearshore shelf conditions. In the satellite image left, (if you would please look past the black no data pixels), youwill see that next to the coastline there is a wide strip of blue. This would be cool temperatures, below 21 C, which favour sardine occupation. This is very positive and may be the combination of the NE winds interacting with cool water that gets dragged up onto the continental shelf, ironically, by the warm Agulhas Current. There is every reason to believe that sardines may swim northwards up the coastline into this cool water. Of course, they may then be more widely spread across the continental shelf, but if the Agulhas Current then moves shorewards, we’ll see these fish getting compressed onto the coastline. It makes for interesting times. For now, it is great to see that the cool water has stretched up along the KZN coastline, and what have we seen thus far? The arrival of the sardines! This shows that despite the vaguaries of satellite prediction mentioned in my earlier blog, these images are VERY useful in predicting sardine movement!

So Vic Peddemors has arrived from Australia and we are all set to head down to the Wild Coast tomorrow morning. We’ll be filming predator baitballs once again. Ironically, we’re hoping for very little activity, so that the predators will be concentrated upon fewer prey, which will make feeding events easier to find. I guess it’s a bit like finding animals around a watering hole during the dry winter. Happy days indeed…

Happy to be heading to the Wild Coast

upping the ante

Good news, there is a lot more activity. The KZN Sharks Board flight from a couple of days ago reported sardine run activity in the Mbashe River region. This shows that the sardines have moved northwards into the Wild Coast. The satellite image for the 15th June

sea surface temperatures from the 15th June 2009

shows that the Port Alfred nearshore cooling (see previous blog) has intensified and reaches up to the Mbashe River region. Previous research has shown that sardine northward movement is constrained in regions where the nearshore cooling meets warm Agulhas Current water. This is clearly visible in the Mbashe River region (the part where the dark blue water meets the green water at the coast). This results in dense concentration of sardine and predators, as reported by the KZNSB.

Also apparent in the satellite image is the strip of cooler water (< 21 C) near Waterfall Bluff and stretching up into KZN. Much of the sardine that moved northwards over the past two weeks will be found in this water. Yesterday, Barry and co found a lot of gannet feeding activity at Waterfall Bluff. It all adds up.  That strip of cool water is reaching into KZN – we should get some netting in KZN within the next week!! But it’s probably just the small stuff so far – hopefully the big stuff will follow, conditions permitting of course. If the warm water pushes up against the coast, any sardine activity will be pushed against the shore. Result? great sardine run activity!

 

You can follow sea surface temperatures at: http://www.rsmarinesa.org.za/index.php

Still waiting

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Barry Skinstad and his Earth Touch marine crew battled to find common dolphins yesterday. These animals are closely associated with sardine presence and their absence is interesting. I will come to that later. In the meantime, Barry and co have been filming large pods of bottlenose dolphins. These pods are likely to be members of the migrant stock. Basically: you have a resident stock around the SE coast, but every winter, in association with the sardine run, bottlenose dolphins from a migrant stock swim up the east coast. It’s not clear how much they feed on sardines – stomach analyses need to be completed, and during these analyses it will be critical to differentiate between migrant and resident dolphins, as the residents do not appear to feed much upon sardine. Differentiation between residents and migrants can be done with genetic analysis as these stocks differ significantly in their genetic make-up (providing evidence for their separation into different stocks). I wonder if there is any factional/ xenophobic friction between these groups?A more likely scenario is that the migrant dolphins are feeding on migratory fish that follow the sardine run e.g. shad, hence the migrant stock close association with the sardine run.

Something else of interest: resident bottlenose dolphin are usually sighted close to shore, almost always within the 30m isobath (depth). Barry’s pod was 7km from shore. These dolphins could have been representatives of the offshore stock, as Barry suggests, however, the size of the pod, and similar previous sightings far from shore in this region, suggests to me that they were migrants. If anybody is interested, I could post a review (by Peddemors) of the bottlenose dolphin stocks on this blog. It might be that the migrant stock has a different distribution to the residents i.e. they might not be as depth-restricted as are the residents. It is of considerable interest that we regularly see bottlenose dolphin out in water way deeper than 30m in the region to the north of PSJ stretching up to Waterfall Bluff. Something to mull over anyways.

So, where are the sardines? The latest satellite image, from the 12th, shows that there is a very cool (well below 20 degrees C) upwelling node of outcropped water north of East London, and that this is reaching into the Wild Coast. I would bet my house on the presence of the common dolphins there (if I had one). That may be why Barry saw so few common dolphins – they may well have gone down for the smorgasboard. Let’s hope that the upwelling of cool water strectches up to Port ST Johns within the next few days of satellite images. If this happens, then it will be time for us all to enjoy the smorg!

We’re off to PSJ on Monday week. The timing is starting to look awfully sweet. Provided this upwelling turns into an event of substance, we should see some good sardine movement northwards. I will try to contact the Lower Wild Coast to find out about sardine run activity.

So long people, not long now

Sean

waiting in suspense

There have been reports of pilot shoals in the Morgan Bay area. This is good news and everybody is holding their collective breath. The latest available satellite imagery, obtained for the 6th June, however, do not show nearshore cooling of sea temperatures extending up the coastline. We’d like to see a nice cool strip of water reaching right up the coast to make a prediction of good activity, and at the moment that is not visible. Satellite images can be tricksy, though. When westerly winds blow they force warm Agulhas Current surface water shorewards, giving the impression of very warm inshore conditions (  http://www.rsmarinesa.org.za/index.php ), whereas there may be cooler water underneath. But then, the strong westerlies that we’ve just had should have thoroughly mixed up the water column, which would make the images truthful. Confusing? Throw in cloud cover effects, which create no data pixels wherever clouds loiter, and an unavoidable time-lag of a couple of days, and you begin to understand the difficulties of using satellite imagery to predict the sardine run.

Good luck with your waiting,

SEan

Slow start to June

The sardine run has not gotten off to an early start this year. Sheldon Dudley, via Mike Anderson-Reade who is conducting the KwaZulu-Natal Sharks Board (KZNSB) sardine run flights, reported largely quiet conditions with some activity in the Morgan Bay area. Along this part of the South African South East coast there is a semi-permanent upwelling cell, which provides better conditions for sardine habitation than further up the coast. This probably explains the sardines’ presence there. Satellite images for late May and early June show water temperatures well above 21 C, which does not favour sardine movement up the east coast. The latest available image (obtained on the 5th June – see http://www.rsmarinesa.org.za/), shows that water temperatures are starting to cool down again, and the effect of the warm Agulhas Current upon the nearshore conditions appears to be subsiding. This is positive, and we might see some sardine movement soon if conditions continue to cool down. Ideally we would like the upwelling, alluded to earlier, to stretch right up the Wild Coast to Port St Johns, as this will give the sardines a conduit to reach the Waterfall Bluff area, which is critical to sardine northward movement into KZN.

Barry Skinstad, at the Earth-Touch Marine website ( http://marine.earth-touch.com/ ) filmed some feeding activity to the north of Port St Johns, but this is mostly east coast roundherring, or red-eye, (or as my friend Greg observed in the surf the other day, dread-eye).  Our data show that predators gather in the Watefall Bluff area prior to the arrival of the sardines, and while they await the main course, must content themselves with dread-eye. YOu could do a lot worse than watching a pod of common dolphins work a pocket of these fish, keeping them nice and tight with cooperative feeding, whilst gannets take the opportunity to feed upon the fish in their panicky state. Do gannets and dolphins benefit from each other’s presence? We’re trying to figure that out with our underwater analyses. What we do notice with small baitballs is that common dolphins corrale the fish for a few minutes, probably taking a breather, then upon a squeak from one of the members of the pod (clearly visible as bubbles emitted from the blow hole), the pod members attack the baitball, often from below, and shear off a few fish from the outside of the baitball whilst other members make sure that the fish don’t escape. Quite often the fish are chased upwards, and being not fish of the flying variety, have no further room to escape. This must aid the birds (Cape gannets mostly) in capturing fish, and a preliminary look at our data do suggest that birds synchronise their dives (predation events) with common dolphin attacks. To determine whether either of these species benefit we’re looking at capture success rates. I’ll post our results once we’ve analysed all our data after this year’s run. Sharks, those old no-do-gooders, do absolutely nothing keep the baitball together and periodically help themselves to the efforts of the common dolphins. After all, it is must easier to feed on a tight knot of fish than when there are millions all around your ‘doughnut’. For those of you who haven’t see the sardine run in its splendour… We often get sardine shoals that are well over a kilometer in length (a really spectacular shoal can be 15 km long), and swimming in between these millions of fish are hundreds of spaced-out sharks (not from eating dread-eye). When viewed from the air the shoal looks like a long black oil-slick, and interspersed are clear rings of water through which the shallow sea bed sand is visible, as well as a shark, hence the ring of fish. This is called a doughnut. Didier Noirot, filming for the BBC’s Nature’s Great Events show, stated that sardines were not able to catch fish when they were in ‘dough-nut’ formation. It seems very likely that sharks’ capture success is much higher when fish are in a tight bait ball and the sharks can basically swim through this ball with their mouths open such that these mouths fill with fish. Oh heavenly delight, I’m sure. One would imagine this to be of great benefit to the sharks, but what do dolphins get from the deal? I’ll, er, keepy you posted!

Get the fever!

Sean

Welcome

HI, welcome to my sardine run blog. Here at the University of KwaZulu-Natal we’re entering our 6th year of sardine run research and are looking forward to this year’s run immensely. We’re heading down to Port St Johns on the 22nd June and will be there for three weeks. Whilst down there we will be filming underwater feeding in an attempt to understand the feeding dynamics of predators. We’d like to know whether the predators benefit from the presence of other feeding predators on bait balls. I’ll be doing daily updates (communications permitting) on our boat life and life in PSJ generally. Feel free to add any comments you’d like.

Till such time,

Sean