November 2009

 

November has been an exceptional month for shark sightings. The month started with some strong westerly winds blowing consistently for the first week. This made working conditions a little difficult in joubertsdam which is an exposed and gets very choppy-quickly. However when the winds finally died down- water temperature climbed substantially remaining above 16º C for the rest of the month. On the 22^nd, 26th 27^th and 28^th the water temperature climbed up to 17ºC! the warmest temperatures all year!- needless to say- the divers had a blast in the cage!

 

 

 

 

Resights and shark activity

 

 

As usual we recognised quite a few familiar fins during November- with shark activity very high all through the month. Gill was our first familiar shark to arrive. She is a large (3.2m) female we first named and identified in September 2007. Since then she has been resighted at Dyer Island (2008) and on numerous occasions this month. Her distinguishing feature is her ‘ Orions belt’ shaped pigmentation on the right of her dorsal fin. This shark also has a real personality and always comes across as very relaxed.

Another familiar fin this month is ‘Wolfgang’ -a small female shark Olli (our other marine biologist) named and identified in Mossel baai. On arrival in Gansbaai he immediately recognised her and matched her dorsal id. Wolfgang (named after a German videographer) has a small white pigmentation spot on the right of her dorsal and is a feisty shark- often rushing about. ‘Moony’ was the third distinctive resight and arrived at the end of November. This shark was last seen at Dyer Island in July 2008. She has distinctive crescent half moon shape on the right of her dorsal and a very inquisitive nature. She loves to pass by the cage very slowly indeed- and always seems to turn with her belly angled towards the surface- stunning shark.

 

Finally the most exciting resight of the month was ‘Prop’. This very special female shark was last observed at the beginning of the year- and documented in November 2008. Sadly she had a chronic propeller injury on her ventral surface- just between her head and dorsal fin. This was sustained from a recreational vessel in the bay who relayed the incident immediately afterwards. Every opportunity to document her wound was utilised via underwater videography and surface photographs during her stay. ‘Prop’ returned during the second week of November this year and was hardly recognisable. Her wound had completely healed and there was no raised scar tissue or clear indication there ever was a chronic wound! On close inspection of the healed wound it is clear to see these sharks have an incredible healing ability and rate. This is a topic we are now busy compiling a research paper on- to compare the white sharks healing to other animal taxa.A very interesting topic.

 

Alot of sharks have been observed with bite marks on their bodies this month- many of these bite marks are from ‘smaller mouths’. One theory is the possibility of bull seals. There are many of them around Geyser rock now and these large seals are known for their aggression and ability to inflict a bite on an opposing animal.

 

 

 

 

 

Sharks in the shallows

 

November is always a spectacular time to view sharks in the shallows in Gansbaai. It’s always so fascinating to see how many individuals crowd and patrol such a small area of coastline. On various occasions this month we launched the Dyer Island Conservation trusts new research vessel ‘Lwazi’ and patrolled the shallows to make observations on the sharks movements. Interestingly the sharks seem very unresponsive- and distracted. They did not respond to a decoy after various attempts. Over 20 individual sharks were observed in the shallows on the 20^th of November! A gyrocopter took to the air- working with us on the 27th and filmed from above. Its stunning to see just how much the dark silhouettes of the sharks stand out on the sandy bottom and also just how close to the beach they get. The aerial footage revealed some really interesting interactions between sharks too.

At the same time- talking to the local fishermen in Kleinbaai revealed some excellent Chokka and Geelbek catches in the same area as the sharks.

 

 

 

 

 

 

Dolphin activity

 

On the second week of November we observed tiny bottle nose dolphins- no adults with them- cruising just next to white sharks along the beach. It seemed as if the sharks were circling the quick and agile little dolphins- then the dolphins disappeared. Similarly the indo pacific humpback dolphins have been observed in the bay again on various occasions.

 

 

 

 

 

Seal activity

 

There have been numerous predations documented this summer season in Joubertsdam. It seems that the sharks will readily go for a seal if it is in the area. Up at Geyser rock the young of the year cape fur seal pups are battling with getting swept off the rocks. At this young phase they are very weak swimmers and often tire out and drown. One baby we rescued in shark alley was in a bad way. With its umbilical cord still attached the tiny seal had no energy and was coughing up water. Nature has to be cruel to be fair sometimes. There are always a large amount of bull seals on Geyser rock this time of year. As mentioned before- these menacing seals have been observed chasing sharks away actually in Shark Alley previously.

 

 

 

 

 

Whales and birds

 

Southern right whale season has been consistent however the whales are fewer in number this year than previously. The whale whisperer’s skipper Albert Scholtz informed us that there are currently seven mother calf pairs in Pearly beach- but the young are very small and new born. This in turn makes the mothers extremely protective of their young ad often if a boat is around the pairs will dive down.  Bird wise- we have seen lots of swift terms this November- they are now starting to synchronise their mating flights. Its incredible to see how far the pairs can swoop down together in perfect synchrony! Also a few Caspian terns have been sighted (relatively rare). On the first week of November an albatross landed on the back deck of a shark boat and sat preening in front of the clients for twenty minutes- this just goes to show- one never knows what to expect on a trip out to sea in our area!

 

 

 

 

August 2009 update

 

Still lots of sharks!

 

August has continued to be a great month in terms of white shark sightings in Gansbaai. We are still finding an abundance of very active great white sharks all around Dyer Island. 10 sharks a trip seems to be the monthly average with numerous occasions logging as many individuals as 20! In 2007 by the end of August (the 28th) the sharks had already left the island and in 2008 it was the 20^th of September we eventually moved off down to the shallows to find them (last years huge storms we think were partially to blame). However the general consensus this year is that the sharks will leave the island later on again. There have been sharks sighted in joubertsdam already by pilots flying over the bay. On the 24^th of August the whale whisperer reported a sighting of a great white shark to us in the shallows at 13.37pm. Weather conditions have been quite forgiving for this time of year. August is always usually our most stormy month in Gansbaai but fortunately the wind has predominently blown westerly for only short periods and slacked off giving us regular gaps to get out behind the lee of Dyer island. On days where the wind direction changes dramatically from easterly to westerly we anchor on completely opposite sides of the island not only for calmer conditions but because of the islands strong current systems. This can delay things as often it takes a while to pick up sharks after shifiting over to the other side of the island. Spatial patterns of activity indicate that white sharks stalk prey downstream in oceanic and tidal currents' (Pyle et al 1996) strong et al found that white sharks often circle dowstream of islands and bait sources apparently as part of a searching pattern'.

 

Water temperature has remanied consistently between 14 and 14.5 celcius this month. This winter we have not seen the water temperature rise to its normal high of 16 celcius plus. There is a lot of debate about how water temperture effects shark movements and activity levels. Carey et al 1982 found that telemetered white sharks preferred to forage along thermoclines perhaps for orientation or to enable the samping of two water masses. This study is now realtively dated however.

 

Familiar fins and faces

 

 

As usual we have had some fascinating animals in the bay this month. Monique Fallows of False bay talked about a small shark named Marshmallow in her newsletter last month. Sometimes the small sharks really are the animals full of beans- more so than the larger sharks often. We have had some lovely juvenille male sharks this side in gansbaai just displaying the most wonderful relaxed and confident behaviour. One particular animal had a lot of scratch markings around the snout area and continuosly made slow vertical approaches lifting its head clearly out of the water. We saw rhe shark regulalry for the last week of August. A lot of sharks have been quite heavily encrusted with copeods this month (a type of marine crustacean that hitches a ride on the shark). Also two sharks were seen with remora fish swimming with them on seperate occasions this is a relatively rare evnt only on a select few occasions have we seen remoras accompanying great whites.

 

 

 

Whale activity

 

Elsewhere in the bay whale sigthings have been quite consistent. Last year the frequency of sightings was higher but is may be that we are having a late whale season usuallyocotber is the month it really peaks. Our whale watching vessel witnessed what appeared to be a breeding southern right whale mid agust. This spectacular event is extremely improtant to document.

 

 

 

 

Volunteers

 

We have had an incredibly busy month volunteer wise! Some fantastic people from overseas have joined marine dynamics and white shark projects to help with crewing on board and data collection. Thanks in particular to Vanessa from germany, Saskia from the UK, Linda from germnay, Manuel from germnay, Caroline and Atumn from the UK, and gina from Austria. These guys have been such a great help on board and their enthusiasm and passion for the white shark has shone through the whole way- well done!

 

Birds and seals.

 

Some of the winter birds have started to disappear form the area now. In particular there anre fewer subantarctic skuas around now but still plenty of giant petrals and shy Albatross. We are still eagerly awaiting the ersults of our tagged cape fur seals. Everyday we pass by the radio recivers on geyser rock and explain to the public what is happening. Researchers did a maintainenec check at the end of the month.

 

September 2009 update

 Busy with great sea conditions!

July has been a spectacular month for our shark sightings. Unexpectedly, our winter weather has not affected shark trips too drastically with most days spectacularly calm with flat seas.

July began with an average of 9-14 sharks a trip and remained that way the whole month. Some days at least 17-23 sharks were logged (on a single trip) at our boat which is just incredible. Liasing with other operators similar sightings were reported all around the Dyer Island area.

Communication between white sharks

Since the Great Whites have been around in such high abundance this month we have had the nice opportunity to make some spectacular behavioural observations. Often on trips there would be three sharks in view at our boat at a time- with dominance displays and jerky body displays happening regularly. Great White sharks are silent hunters and don't make noises to communicate but rather warn off con specifics by certain body language signals. Our underwater videographer and volunteers (who have had endless cage time this month) validated these body signals. Gestures such as the lowering of pectoral fins- arching of the back, flicking of their caudal fin and gaping are all signs that a shark is feeling uncomfortable and that someone/thing is in their personal space. Great Whites are such transient animals in Gansbaai we cannot really say they are territorial over specific areas of the reef. They are territorial however of personal space especially when there is a potential prey item in view!

 

Special sharks this month.

Known as 'big girl' to other boats we nicknamed this beautiful shark 'Terry' after one of our British volunteers on board. What an animal she is! Terry arrived at the beginning of July and has remained in the area the entire month. Usually, we tend to see with the bigger sharks around our vessel that they circle us for a while and then move on. This shark however was definitely an exception to the rule. Measuring in at 3.8- possibly larger and with a relatively fresh scrape wound on of the leading edge of her dorsal this large female makes the most beautiful vertical approaches to our bait and endlessly lifts her head completely out of the water. Not only that, Terry loves the seal decoy and almost as if playing with it will continuously make attempts to grab it but without actually biting it- just nudging it. She has become a real favourite with clients and volunteers- probably for all the fantastic photo opportunities she has provided.

Just when we thought our notorious Slashfin and Nemo had left the bay both animals have been sighted in the last few days of July. Nemo definitely looks like she has gained a little bit of weight around the middle. Both sharks are real winter visitors to Gansbaai and its good to see both are still as spectacular as usual.

The majority of sharks have been sub adults measuring on average 2.8m. There have been so many 'characters' its too much of a task to name them all. Two Male sharks had the remainders of old tags lodged behind their dorsal and several sharks have had fishing hooks lodged in their mouths sadly. Interestingly, quite s few sharks have been spotted with the entrails of their breakfast seal pup streaming out of their gills- yummy! This is a nice reflection of natural predatory activity going well this month.

 

Tagged seals on Geyser Rock.

At the beginning of July a tagging program was set up on Geyser rock- (Gansbaai's Cape fur seal colony) with Marine Coastal Management visiting the area to carry out the ground work. In total, ten cows and ten pups were fitted with transmitters (two types of 'speaker' tags). Three receiver towers were deployed on Geyser rock in order to capture the signals from the seals. As far as we know the tags will stay on the seals for three months and the data will hopefully reveal how far and exactly where the seals head off to feed from the island on a daily basis. The results have been reported as very encouraging so far. We are eager to see the results. Last year a couple of our Penguins on Dyer island were tracked and swam almost 25km in a day for their food- unexpectedly far distances for the impressive little birds!

 

Whale season.

Southern Right Whales are back in our area- not in full force yet- but consistent mother and calf pairs also plenty of Humpback whales have been passing through the area. One day whilst on a shark trip- four humpbacks (two calves and two cows) swam so closely off our stern. It was an amazing experience to hear them calling to one another with a tremendous blow every so often- stunning animals and photo opportunity for our guests!

 

Stranded Risso's Dolphin:

At the end of July a Risso's Dolphin Grampus griseus was found washed up off Danger point just off the rocks at I&J Abalone Farm (Gansbaai). We got permission to go through and photograph the dolphin which measured just under 3m. The Risso's dolphin is an offshore species which doesn't approach boats readily. Their particular prey preference is squid. These dolphins are a dusky grey/black-blue colour with a distinct rounded-melon shaped head. They have lots of white marks and scratches all over their bodies from either their squid prey- other dolphins biting them or parasites. Reasons in the past for the species stranding are bioaccumulation of toxins and internal parasites. There is a type of trematode (Parasitic worm) that reportedly eats away at the cranial nerve of the dolphin. Exact results of the stranding will hopefully be verified at the marine mammal institute at the museum in Cape Town by marine mammal expert Meredith Thornton. Natural death by old age or sickness is also a highly possible cause as the dolphin was believed to be a mature adult.

 

Sea birds- shark bitten penguin.

As usual during winter months we sight spectacular sea birds out at sea in Gansbaai. We have been encountering some huge Giant Petrols n the area- some so heavy that they struggle to take off again once landed on the water! On the 29^th we found a poor penguin floating in shark alley and took it back to shore. Unfortunately the bird had been dead for a while. Examining the animal closer a bite wound was clear- and the culprit a shark. Sharks kill penguins rarely in the area of Gansbaai and this is only the second time in three years we have collected a shark bitten animal on our vessel. White sharks are infrequent predators of sea birds at Dyer Island, perhaps due to an abundance of Cape fur seals (a preferred prey), anti predator behaviour by penguins, and sea birds not being a preferred prey type (Johnson et al 2005).

 

 

 

 

 

Hi there

Well first of thanks to Sone and all her hard work the website is looking stunning- well done!

So, here follows the start of my blog. What i shall try and do is update on a weekly basis details of any interesting news with regards to sharks and any other science/conservation based topics.

Monthly breakdown/discussion of our sharks is better detailed in my newsletters which you can subscribe to on-line- home page.

 

 

Thanks to Marine Dynamics volunteers February-March-April

We have had the most amazing volunteers join us on the MD volunteer program recently. In March Tami, Penny and Gina joined us from the states, followed by Allyson from Canada in April. They were all an absolute pleasure to have on board. Their hardwork, humour and enthusiasm on shark Fever everyday was much appreciated especially as the shark sightings took a bit of a strain at times. Thanks for being such great team members girls, and hopefully we will be seeing Tami back again in May/June (We cant blame you for not being able to stay away!).

 

 

Winter begins:Large sharks followed by cold water:

Interestingly the start of our winter season here in Gansbaai, saw in a batch of female sharks at the island. Some clearly marked with mating scars around their gills the females were highly active and very responsive to chum lines. Notably the vast majority of these girls were over three meters in length and a few individuals were some of the largest animals I've ever encountered here in almost two and a half years! (4.5m). The presence of these sharks occurred just after a previous group of large males(Geldesteen location) just weeks before. We know there is a more mixed ratio of males and females observed at Dyer island in winter months, but these sightings clearly indicate a sex based dispersal of mature sharks with indications of possible mating attempts. Very encouraging observations given the fact nobody has documented shark mating between whites in SA before and all we have is speculation!

 

Return of Nemo!

One of our most infamous resight sharks (regular visitor to the bay) 'Nemo' was sighted behind Dyer island in the channel mouth this month. Shark Lady's crew confirmed the juvenile white sharks presence. I first recorded Nemo in September 2007. The distinctive (then 1.8m long female) has half her left pectoral fin missing and the dorsal fin has been sliced in half. Explanations for such injuries could be attempted finning but I'm swayed more towards the theory the shark got wrapped up in some kind of rope or line and struggled. After observing the shark in joubertsdam in 2008, we have documented her as one of the few animals to visit both the island and inshore locations. On this latest encounter with her she was said to have grown in length to almost 2.8m- which is fantastic and shows despite her injuries she is a relatively healthy and successful in feeding.

Craig Bellamy

It's always nice to have celebrities on the boat, and this month we were joined by Uk soccer star Craig Bellamy on the 14-04-09. Craig plays for Manchester city football club and is the welsh team captain. ( i had to swallow my pride as i'm a Manchester united Fan but hey!). He thoroughly enjoyed his exclusive trip with Marine Dynamics and his little boy helped me record data and dorsal fin id the sharks. We saw 8 sharks that trip and had a 4.5m female put on the most amazing display. I felt Craig really got an appreciation on why the Great White shark is the great white shark, and his compliments on the excursion were received with pride from our crew!

Other soccer stars we had previously on board include Gordon Strachan (Celtic FC manager) and Bobby Charlton Manchester United.

Sea birds:

Excellent to see the return of our Sun Antarctic skuas and petrols back in the bay. On the few occasions this month we have been lucky enough to witness Albatross and small storm petrols- stunning.

As Marine Biologist researcher, scientist and staff member of Marine Dynamics, my life is committed to study the Great White Shark - the success of evolution and beauty of nature in all its power. [Alison Tower, Bsc Marine Biology]

This is for testing purposes......