City warns beach users of inshore movement of sharks over the summer season

The City of Cape Town would once again like to remind all beach users that the time of year is approaching when a seasonal increase in the presence of white sharks in the inshore area is expected.

This seasonal change is not recent in its occurrence or unique to False Bay. Similar trends are recorded in Gansbaai, Mossel Bay and California - all areas that white sharks are known to frequent.

Shark sightings recorded by the Shark Spotters have consistently shown a seasonal increase during the period from September to April, peaking in mid-summer. Typically shark sightings start in late August and the City is therefore appealing to all beach users to be aware of the expected increase in shark presence in the inshore area over the summer months.

White sharks are present in the Cape's waters all year round and the possibility of encountering one of these animals at any time is minimal. However, beach users should always remain vigilant.

The graph below shows the sightings recorded over the last six years of shark spotting, clearly indicating seasonal trends.

The data has also shown that shark sightings increase significantly at beaches where a whale carcass has stranded. These sightings may persist for up to a week after the whale carcass stranding. The City will therefore close relevant beaches where there has been a whale stranding, and appeals to residents to understand this precautionary approach.

Kayakers and surf-skiers specifically are asked to be cautious of the area between Sunnycove and Glencairn Beach, and swimmers are urged not to use the water off Jaegers Walk in Fish Hoek as this is considered a high-risk area. The City has erected warning signs along Jaegers Walk.

Surfers are asked to be especially vigilant in the areas between the Sunrise Beach and Macassar Beach area during the summer months, as research has shown these to be areas of highest shark presence in False Bay in summer.

Update on exclusion net trial programme

The City's Environmental Resource Management Department is on track to trial the exclusion net at Fish Hoek during the 2012/2013 summer season. It is currently planned that the trial could take place from January 2013 onwards as certain matters are still being finalised. This includes:

• on-going discussions with the trek net fishing rights holder at Fish Hoek beach, to ensure that the exclusion net does not impact on his fishing activities; and
• finalisation of the permit required from the Department of Agriculture, Forestry and Fisheries before any trial can take place.

Shark Spotting programmes are operational at the following areas:

Summer (From start of school holidays, 28 September 2012 until 9 April 2013):

Winter:

Shark Spotter research yields new information

In addition to providing a safety service, the Shark Spotters collect valuable information that contributes to a better understanding of white shark coastal occurrence and behaviour. This information can in turn be used for local awareness campaigns to enhance beach safety.

More than 1 300 shark sightings have been recorded since the programme began in 2004. Previous analysis of the sightings has demonstrated a clear seasonal trend in occurrence, with most sightings taking place over spring and summer (September to May) for all beaches. The most sightings were reported in Muizenberg, when compared with Fish Hoek, St James, Clovelly, Glencairn and the Hoek (Noordhoek). In addition, most of the sightings, i.e. 73.8% took place behind the surf zone in deeper water.

A recent study, which used the information collected through the Shark Spotter programme, conducted by University of Cape Town (UCT) Masters graduate, Kay Weltz, in collaboration with Alison Kock (Shark Spotters), Prof. Colin Attwood (UCT) and Dr Henning Winker (UCT) investigated the influence of environmental variables on white shark sightings at Muizenberg, St James and Fish Hoek. The study found a significant relationship between shark sightings and water temperature at all three beaches. The analysis demonstrated increased probabilities of shark sightings as water temperature approached and exceeded 18⁰C.

The influence of the lunar phase was consistent with an increase in sightings just before or at new moon at Muizenberg and Fish Hoek. No significant relationship was found for the lunar phase at St James, which is likely due to a shorter time series of data available for analysis.

The relationship between shark sightings and warmer water temperature is more than likely linked to an increase in prey availability. Similarly, the increase in sightings just before or at new moon is likely to be the result of an increase in prey availability (although the mechanism influencing this remains unclear).

Finally, the study found that the number of shark sightings changed each year, with no trend evident between 2004 and 2008; however, it identified an increasing trend of more sightings over the last three years at all three beaches. This increase is suspected to be either due to more sharks using these inshore areas or sharks spending more time at these sites over this period. Continued monitoring will provide a valuable tool for assessing and hopefully explaining this trend in the long-term. Individual spotters, cloud cover, wind direction and wind speed were also considered, but were not found to significantly influence shark sightings.

None of the variables, such as water temperature and lunar phase or year, influence the ability of spotters to detect sharks and therefore represent actual shark behaviour in the inshore area at these beaches. The finding that individual spotters, cloud cover, wind direction and wind speed had no significant relationship with shark sightings provides evidence that the Shark Spotting programme is an effective warning system.

These findings of the Shark Spotting data are being written up for publication to be submitted to a recognised scientific journal.

Although these findings provide us with more information to increase safety, beach users should bear in mind that these are trends. White sharks have been recorded in the inshore area in all environmental conditions, including in very cold water temperatures and at full moon.

"This research and the other research that has been made possible through the data collected by the shark spotter programme shows that the City is committed to doing everything possible to improve the safety of beach users, while recognising the important role that white sharks play in our natural environment. While this research is still new and underway it gives us important insights and demonstrates the value of the shark spotter programme", said Alderman Belinda Walker, Mayoral Committee Member for Economic, Environmental and Spatial Planning.

Shark safety tips

Beach users are encouraged to use areas where Shark Spotters are on duty and to take the time to speak to the Shark Spotters on the day they visit the beach to find out about recent sightings and activity as well as the current conditions which determine the effectiveness for shark spotting.

Beach users are also requested to please take the time to familiarise themselves with the Shark Spotter signage and to ensure that they understand the four flag warning system. They should be aware of the use of a siren to close the beach.

It must be borne in mind that no safety measure is 100% effective. Although the Shark Spotting programme has been successful, it remains vulnerable to human error, weather conditions and water quality issues.

The following tips can help reduce the risk of attack:

• Do not swim, surf or surf-ski when birds, dolphins or seals are feeding nearby.
• Do not swim, surf or surf-ski near where trek-netting, fishing or spear fishing is taking place.
• Do not swim in deep water beyond the breakers.
• Do not swim if you are bleeding.
• Do not swim near river mouths.
• Do not swim, surf or surf-ski at night.
• Do not swim, surf or surf-ski if there has been a whale stranding nearby.
• If a shark has recently been sighted in an area where no Shark Spotters are present, consider using another beach for the day.
• First-time visitors to beach areas should ask the local law enforcement official, life guards or locals about the area.
• Obey beach officials if told to leave the water.
• For those who are kayaking or surf-skiing far out to the sea, consider paddling in groups and staying close together (in a diamond formation).
• Consider using a personal shark shield when you go surfing or kayaking.
• Pay attention to any shark signage on beaches.

For more information on the latest shark sightings and research please visit: www.sharkspotters.org.za. The public are encouraged to report any sightings of white sharks to the Shark Spotting programme via this website.

Statement issued by Gregg Oelofse, Head: Environmental Policy and Strategy, Environmental Resource Management Department, City of Cape Town, September 4 2012

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