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