07 October 2005

South Africa: Great White sharks move to shallows - Hot spots revealed

Shark watchers along the False Bay coast say several Great Whites were seen among the breakers less than 60m from the shore during the peak December holiday period.

In Muizenberg most of the sightings were slightly further out - between 180m and 240m from the shore - in the area used by surfers and paddleskiers.

But these sharks were not acting aggressively or paying any attention to the bathers - and there is now speculation by scientists that the two bays could be among the historical breeding sites of this magnificent but much maligned and misunderstood top ocean predator.

The key observations were made last summer by the shark spotters on Boyes Drive above Muizenberg and on the Fish Hoek mountainside, and support the hypothesis of scientists researching Great Whites (correctly known as White Sharks).

The observations are made public today after a lengthy debate by the Shark Working Group set up informally after the attack on young Muizenberg surfer "JP" Andrew in April last year, which cost him a leg, but formalised after several other shark attacks later in the year.

The group is co-chaired by the City of Cape Town and the Marine and Coastal Management branch of the department of environmental affairs.

Members include scientists and field researchers from the White Shark Research Unit of Iziko-SA Museum and other institutions, and representatives of the National Sea Rescue Institute, the SA Surf Lifesaving Association, surfers, conservationists and the fishing and shark cage-diving industries.

Group spokesperson Gregg Oelofse said the group agreed the recorded observations were shocking on the face of it, but that this had to be seen in context and should not deter visitors from enjoying these beaches in the coming season.

"This is not something to panic about and we don't see this as a major problem," he said.

"But we also don't want to give people the wrong impression and it is really appropriate that they know what is going on in the sea and can make their own decisions - we don't want to pull the wool over anyone's eyes.

"We also want to demystify the White Shark - it is definitely not some 'mythical monster from the deep' that keeps attacking people."

The working group released maps showing observation by the shark spotters between November 15 last year and January 31, when large sharks repeatedly swam into shallow water.

But sightings at Fish Hoek ended abruptly on December 26, and at Muizenberg on January 18.

The number and frequency of sightings since then has been extremely low: none at Fish Hoek until last weekend when one took a bite out of a kayak, and only three in February, seven in March, one in June and seven in September at Muizenberg.

Oelofse said it appeared from this data that more Great Whites occurred in the inshore zone during the summer months than in winter.

"This pattern is starting to repeat itself now, and this is further supported by research work by UCT Ph D student Alison Kock, which indicates a high density of these animals around Seal Island in winter and dispersing in summer."

Kock and her team identified 150 individual Great Whites off Seal Island during this winter, Oelofse pointed out.

"No one is quite sure what is behind this pattern, but it is most likely driven by a range of factors, all related to this natural behaviour of sharks."

Kock has placed 29 bottom monitors at all the inshore bay areas in False Bay and has fitted acoustic taggers to 23 sharks.

Each time one of these sharks passes within about 300m of a monitor, a whole range of information is recorded.

"A key step in this research programme will be to establish if it is the same sharks that occur off Seal Island in winter that also occur off our beaches in summer," Oelofse said.

"It will also give an indication of the extent to which each animal uses the bay and if there are environmental factors behind their summer movements, such as trek-net fishing and the opening of the Zandvlei estuary."

It was also an opportunity for the researchers to investigate whether there were one or two individual sharks that kept occurring in the same area, he added.

"This is an essential and critical step in better understanding White Sharks and any threat they may pose to beach users."

Shark spotters - currently privately funded - would continue their work during the coming season, and a motivation for city funding was being drawn up, Oelofse said.

Also, the shark group was also considering tagging some Great Whites in inshore areas, which would require the use of bait.

"But a decision on this has not been made yet, and in any case it will not be done close to beaches and we will be asking the public for their opinion before any such decision.

"This is an exciting time from a research point of view and the information gained over this summer will potentially help us understand White Sharks and any small threat they may pose to the public."

A "Shark Specialist Review" workshop was likely to be held in February, and its findings would be made public soon afterwards, Oelofse said.

"We believe that people can swim with a lot of confidence this summer, and that they will get good advance warning of any shark presence in the swimming areas."

# For more information on the research, contact Oelofse at 021 487 2255. jyeld@incape.co.za

Source: www.iol.co.za


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