Well what do you know, those little slithery suckers have finally arrived in Durbs. Nice to see cool water stretching all the way up the east coast to KZN!!!!!

BIG REQUEST FROM DENNIS KING: DOES ANYBODY HAVE A PHOTO OF A COPPER SHARK (BRONZE WHALER) FOR HIS MULTI-MEDIA FISH GUIDE????
PLEEEEAAAASSSSEEEE???

I’ll be out on the Natal Bight measuring things, so won’t be on the blog for some time now. The good news is that the thesis is at the printers. toot toot!!

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over for the year

July 13, 2009

So the rsmarinesa website is still offline, and I haven’t downloaded the satellite images for this year’s run. When I do, I will do a synoposis of the run, but that is low on the list of priorities. Although everybody is packing up for the year, the run continues in Port St Johns. Now would be the time to get a little team together and charter a boat down there. You will get activity for the new few weeks, and there’ll be nobody else there.

prey species on the run

prey species on the run

We would like to thank Craig and his staff from Scuba Addicts who kindly provided us with air refills during the sardine run, and would like to thank all other boat operators who participated in the sharing of information about the location of sardine run activity, and for their courtesy in observing etiquette around baitballs. Their behaviour ensured that this year’s run remained an enjoyable experience with no bun fights around baitballs. thanks everybody!!!

film crew gets ready

film crew gets ready

For me, it’s back to the grindstone. Our field trip was a great success thanks to that last fantastic day. Now comes the grind: capturing and analysing all that data (but it is an interesting grind, make no mistake!).
I’ll be blogging again next year, when we’ll be putting critter cam and all sorts of groovy motion sensors on bronze whaler sharks to get a handle on how they feed. It should be an awful lot of fun, as well as serious science, so please join us again during early June 2010.
all the best
Sean

today was the day

July 8, 2009

What an awesome day – five fantastic baitballs, of which, two were in 12 m viz. stunning stuff, but I’m too busy downloading the 4 hours of film we shot today to post on blog. will get a bit on tomorrow, hopefully, but we travel back to Durbs tomorrow, so we’ll see. awesome stunning day!
sounds like there is sardine everywhere at the moment. Sounds like the KZN coast is getting their sardine run too, at last.
I’ll be doing a final summary of our run this year in the next few days – I’ll be paying particular attention to the success (or not) that we had using satellite imagery to predict sardine movement.
happy run everybody,

another strange day

July 6, 2009

fish eagles with fish

fish eagles with fish

Another beautiful day on the Wild Coast with really clear atmospheric conditions allowing for a fantastic view of the cliffs. On our way out we spotted a pair of fish eagles standing on the mud flats of the Mzimvubu Estuary. We noticed that one fish eagle was clutching a fish, and then he flew towards his partner, apparently to share the fish. Very nice indeed. We’re a lot less sharing when it comes to our bait box. In the photo below, you can clearly see the gannets tucking into their bait box, whilst making all the appropriate calls.
the gannets dive onto the bait box

the gannets dive onto the bait box


Today was a fairly quiet day. Once again, within the 100 m isobath, there was plenty of fish, but it’s all deep – right on the bottom. Bits and pieces were brought to the surface, and some feeding was done, but this was mostly within 3 km from shore, and consequently the visibility was marginal. Later in the afternoon, we noticed very heavy but ephemeral activity out beyond the shelf edge, and guessed it was the same small fish as yesterday. When we got out there all hell was breaking loose as over 1000 gannets were feeding on long, thin fish that we’ve subsequently identified as saury, Scomberesox saury, thanks to Justin’s excellent photography. I’ll get a picture from him for tomorrow’s blog. There was a Bryde’s whale swimming through the chaos, but we didn’t see a feeding lunge. The activity was moving very rapidly around the ocean, and it did not ball in one place. Still, the water was clean and there were hundreds of common dolphins and sharks, so we jumped in. The action dissipated almost immediately, but we did have a nice moment when a large dusky shark swam up to inspect Vic and Justin. You can see a quick clip of that below.


All the boats from Mbotyi went north today. That is excellent news – fish must have gotten through Waterfall Bluff and there is a good chance they’re headed for KZN. Will keep my ears pressed to the wall. Still no satellite images for predictions. Sorry.
Happy hunting
Sean

Mzimvubu Estuary in the morning

Mzimvubu Estuary in the morning

The mighty Mzimvubu Estuary

The might Mzimvubu Estuary

It’s now Sunday evening and it’s back to the blog for me. Yesterday the blog was given a miss as it was rugby time, followed by beer drinking time, followed by a trip to the local “night-spot”, which turned out to be really, really pleasant: the local marimba band (a wooden xylophone) was practicing, and they were truly awesome. Some old timer came in to the pub with a baby samango monkey on his shoulder. These monkeys look very similar to their cousins, the vervet monkeys (who recently starred on their own satellite television series), but samangos are much less common. I’m not going to enter into a debate on the virtues (or lack thereof) of keeping a wild orphaned animal as a pet and letting it drink coke out of a bottle at a bar, but I will say that Port St Johns is one of those places where this kind of thing is not out of the ordinary.
on the run from dawn

on the run from dawn

So today we did our usual early morning launch and found that a lot of the activity was close inshore, that is, less than 3 km from shore. We did, however, also find our usual activity out on the 80 – 100 m depth line, about 6.5 km from shore. Once again it looked like little bait balls, and not wanting to scare off any predators, I hopped in alone and filmed a ball for over 30 minutes. The viz was not fantastic, so I won’t upload any of it to show. One interesting event, however, was the arrival of a little school of what looked to be bonito with an entourage of 4 decent-sized bronze whalers (by decent, I mean bigger than me). It was interesting to see them circle the ball once, and then to see the fish swim off into the gloom. The sharks, unfortunately, then chose me to circle around, but lost interest after the third or fourth roundabout, and also departed. The bait ball was being worked by the common dolphins – there was one easily identifiable large individual whose mouth (or beak) did not close properly. He spent a lot of time swimming around the bait ball, often pushing it in a direction. Intermittently, between 4 and 8 common dolphins would rush the ball and feed. When this happened, the few gannets that were in attendance generally also attacked the ball.
After the dive we followed some activity further out, in water deeper than 200 m, hoping to get in on clean water. There was a lot of activity with plenty of diving and another Bryde’s whale. Things were looking very positive, but the problem was that the activity was moving really rapidly, with diving starting up in one place, continuing for about 10 – 15 dives, and then moving off to another place. This would have been the dolphins moving around and feeding in different locations. The birds are very dependent upon the dolphins when feeding. It was interesting that the fish were not balling. We could see that the dolphins were feeding by the amount of scales in the water. Eventually some of the fish were forced to the surface, and we could see that they were very small. There was also no tell-tale smell of sardine, so we suspect that the dolphin were feeding on anchovy, which are generally smaller than sardine. They were also more than 2 km further from shore than our previous sardine shoals, and this agrees with data collected during the 2005 hydroaccoustic cruise, which found that anchovies are usually found further from shore than sardines.
Gannets waiting for common dolphins to start feeding again

Gannets waiting for common dolphins to start feeding again

Throughout the afternoon we watched wave after wave of feeding common dolphin pods moving northwards. Typically, the feeding would start up, and all birds in the sky would hone in on the action. Within 5 minutes, there was usually over 200 birds diving noisily of the dolphins, and then within a further 5 minutes, they would all be sitting on the water and the brief feeding session would be over. However as soon as the next session started, they would take off and go through the routine again. They did this all afternoon, which is unusual; because once gannets have been feeding successfully they sit on the sea surface for at least 2 hours to digest their prey. We suspect that either a) they were not feeding successfully or b) their food was not as nutritious as sardine or c) both of the above. It’s probably c) both of the above, and their prey was probably anchovy.
juvenile gannet with adults

juvenile gannet with adults

Incidentally, we’ve seen plenty of juvenile gannets. Previously, during predator surveys of the sardine run, juvenile gannets comprised between 3 and 6 % of the total number of gannets sighted. This year, there seems to have been more than that. Hopefully it’s a sign that juvenile mortality over the past breeding season has been lower than the usual very high percentage. Juvenile gannets have dark plumage as they have not yet attained the brilliantly contrasting black and white plumage of the adults. When they are moulting into their adult plumage, their heads change to white first, and they look quite funny with a brown body and white head.
So what has happened to the sardine run? Well, this morning, all the boats that are based at Mbotyi headed south to Port St Johns. I therefore suspect that there is very little activity north of Waterfall Bluff, and that is bad news for the sardine run in KZN. It’s looking bleak, but don’t give up yet. On our way in to shore, in water depths from 115 to 60 m, we passed over a lot of sardine, but it was all on the bottom. There is too much warm water above, and they’re sitting down below in the cool water where they are safe(ish). We need the dolphins to bring them up to the surface in a baitball if we want any action now, alternatively, we need cool upwelled water to entice them up. Keep watching the satellite images, and be reassured, the sardine are still around, southwards of Waterfall Bluff at least!

In off the sea early today, 1230, as a westerly buster has arrived. Truth be told, it may not be the worst thing in the world as things have quietened down considerably after the chaos of the early week. A strong westerly wind might just stir things up! During the vicious weather of last week, the gannets would probably have experienced difficulty in feeding, and that may have been why the activity was so hectic for two days after the strong winds had passed. Certainly our data show that gannets feed more after a cold front (= westerly buster) has passed through a stretch of coastline.

baitballWe are finding plenty of fish scattered around – it is easy to find a group of common dolphins working a small baitball. Often there are less than about 200 fish in the ball (picture left), and the common dolphins don’t hang around and corral the ball. These little balls are spread thinly over the shelf along this part of the coastline, and the commons merely move from one little ball onto another. When they manage to round up a nice plug of fish, then the gannets get involved and dive onto the ball. Gannet success rate during these plunge dives seems to be quite high, probably over 30 or 40 %, depending upon the density and size of the ball, and its proximity to the sea surface.

The big sighting of the morning, not made by us, alas, was Orcinus orca, or killer whale. It is not known whether these dolphins (yes, they are not whales) eat sardine, but there has been some footage of them eating dolphin, and lets face it, there’s plenty more dolphin in this sea. Sightings of killer whales along this coast, however, are very rare. It was a very lucky find, indeed.

This morning we headed straight out off Poenskop and were rewarded with some good gannet and common dolphin activity. While we were kitting up, we could see the activity slowing down, and as we were about to jump in the water, a Bryde’s whale lunged to the surface and swallowed the baitball. That was the end of the baitball. There were a few dolphins on either side of the lunging Bryde’s whale, and it’s probable that the dolphins snack on fleeing fish, which must be completely disorientated from the feeding lunge. It is still amazing that we are getting so many Bryde’s whales this far north. Fantastic!!

After that we headed south to Ebulauw (about 30 km south of PSJ) looking for cleaner water, and did manage to get in on a decent little baitball with quite a few solid bronze whalers and the other usual predators, but it was in green water, so not much good footage was obtained. In fact, there is very little clean water around anywhere. We are not sure if it is because of the recent massive surf stirring up fine silt sediment deposited by rivers, or whether it is an algal bloom. We’ll have to get onto the ocean colour website to check.

I have still not managed to get on to the rsmarinesa website. It is most frustrating because I’m getting calls asking where the sardines are. We know that a lot of sardine has come up as far as Port St Johns, and has reached the Waterfall Bluff Bight, but that it has been very scattered to the north of Waterfall Bluff. This area is crucial to the success of the sardine run; here the continental shelf is very narrow, only about 9 km wide. If the Agulhas Current (= warm and unsuitable for sardines) flows up against the shoreline, then sardines will not be able to pass through and make it to KZN. Then the sardines will stay south of the Bluff and we’ll be happy in Port St Johns. If conditions allow, for example, if a cool current gets pulled up on to the shelf and passes north through the Bluff area, even if it is below the surface and not observable by satellite imagery, then there is a great chance that this activity will reach KZN. I hope for ya’ll sakes that this happens.

HUMPBACKSo…when there is nothing going on predator feeding wise, one can always take a moment to watch the many humpback swimming past (pictured left). Over the past few days, we hadn’t seen many humpbacks, but they are back in force again. Humpback whales are known to move in groups where the males travel separately to females with calves. It might be that another pulse has arrived and is travelling in the same area together. We saw groups of 6, 7 and even 8 animals together, breaching and blowing and making the long trek northwards on their breeding migration.

Justin_guttedOn a sad note, you can see Justin (pictured left) hunched over his Nikon D300 camera which was in house underwater housing, which decided to become a swimming pool. Justin managed to get the camera out, but was gutted because a) he didn’t know if the camera was knackered (this is a seriously nice camera) and b) the underwater component of his epic holiday had just ground to a halt. To be fair, he did not throw his toys off the boat, but was REALLY introspective for the next three hours. Happily, Rod siliconed the hell out of the dome port, and Justin was able to dive with his housing today. meet the teamThat is why he looks so happy in the photo of us travelling up the Mzimvubu estuary. From left to right: Me, Rod Haestier, Vic Peddemors and Justin Gilligan.
Good luck with the waiting,
Sean

activity tailing off

July 2, 2009

Another ripper of a day, weather-wise. We started out early this morning and got ourselves nicely stuck on a sandbar in the Mzimvubu Estuary. The large swell four days ago shifted tons of sand over the thin barrier beach into the estuary. This has made the passage through the estuary to the sea very tricky indeed. Luckily a crew of Ukrainians, courtesy of Scuba Addicts of Umkomaas, helped us push off. A big thank you to you guys. Passage through the surf is also very tricky because of the shallow sand banks in the surf zone. Rod, however, is a master at launching and it wasn’t long before we were out.
The sardine run activity calmed down an awful lot today. Our research has shown that gannet feeding activity is highest immediately following cold fronts, when strong winds present feeding difficulties for them. Following the severe double front, and then another one for good measure, last week, we’ve had excellent sardine run activity, but it has been gradually decreasing every day. We’re almost looking forward to the next blow, in the hope that it’ll stir things up again. There’re plenty of fish around – they are visible on the fish finder and the common dolphins are forming lots of small feeding pockets. Our best baitball today contained about 40 common dolphins and plenty of birds – they were really churning up the water with the bubbles from their dives. There were also quite a few sharks, mostly bronze whalers. Water clarity was an issue, though.
Included below are some images taken by John Costello (who owns the Outspan Inn) of Rod skippering his boat through massive sea last Monday. Justin can be clearly seen clinging on to the rails up front, no doubt feeling like he’s in a roller coaster ride.
Rod_launch_1

launch_2

a lovely day…

July 1, 2009

A beautiful day, today. Not a cloud in the blue sky and plenty of winter warmth – once the morning freeze had left the land. Rod is always ready to point out the weather service’s inability to predict the minimum temperature in town – for the past two day’s it has been 2 and 3 C respectively. Not the 12 C they are predicting for tomorrow, that’s for sure. This is because the weather station is in the lighthouse, which is right over the sea. We’re (and the town) are next to the estuary, which is freezing cold, hence the temperatures. Anyway, once the morning freeze had left, it was a beaut of a day. There was, once again, plenty of activity, but nothing like yesterday. Scattered baitballs everywhere, and we got plenty of footage. Only problem was that it was in marginal viz. Such is life on the run. A point of interest on one of our baitballs, besides all the sharks, dolphins and gannets, was a solitary Cape comorant (pictured below).
Cape_cormorantIt is unusual to get this animal so far north, and its presence here today was another symptom of the amount of sardine that has come up the coast. It was nice to see how the cormorant’s hunting style contrasted with that of the gannets. Gannets plunge dive from 30 m, entering the water like an arrow (pictured), and then actively brake at the depth of fish and snatch one if they can. Cormorants do a graceful underwater dance through the baitball with a few passes before returning to the surface.
gannet_diving
Still haven’t managed to log on to the rsmarinesa website to check out the satellite images. The boat crews at Mbotyi report that the activity has reached up there, but it seems to be very sporadic to the north. We’ll have to just wait some more, but there’s still a good chance that this activity will make it to KZN.
Happy waiting,
Sean