Skip to content

ABOUT the course

history of Shark diving in

sodwana bay

In 1993, legislation only allowed snorkelling with ragged-tooth sharks on Quarter-mile reef but this practice allegedly became unmanageable as up to 60-70 divers were entering the water with the sharks at a time. In an effort to control the disturbance, Ezemvelo KZN Wildlife (herein referred to as Ezemvelo), together with the dive operators, set up a ‘card and flag system’ for divers to interact with the sharks on Quarter-mile reef, with a limit on the number of divers, boats and the amount of time each group may spend on the reef with the sharks. In addition to this, all dive operators and their dive masters were required to undergo a training course in shark-diving protocols and procedures and received certification from Ezemvelo. A code of conduct for ragged-tooth shark diving was also developed by Ezemvelo, KZN Sharks Board and the National Department (then Marine and Coastal Management). A daily procedure was followed where each dive operator was allocated a flag and only two boats were allowed on Quarter-mile reef at any given time. The flag was to be returned within a two hour period.

In an effort to protect the sharks and prevent further stress and disturbance, a “gentlemen’s agreement” was established in 1998 between the dive concessionaires and authorities, whereby Quarter-mile reef was closed to all activities, including diving, fishing, snorkelling and spearfishing from 1 October every year. The managing authority would open the reef for divers once the sharks had settled, as they were restless upon arrival every year. In 2006, it was found that not all dive concessionaires were complying with the ‘card and flag system’ and in 2007, after a meeting between the dive concessionaires, KZN Sharks Board and Ezemvelo, it was agreed that all operators would return to the existing card and flag system.

In 2009, the iSimangaliso Wetland Park Authority (referred to herein as iSimangaliso) and Ezemvelo (Conservation Management and Scientific Services) held a meeting with the dive concessionaires regarding the continued implementation of the ‘card and flag system’ but Ezemvelo indicated at the time that the system could not be managed due to a lack of capacity on the beach. As an alternative, a roster system was developed where dive concessionaires would be allocated time slots, based on the number of registered boats. Two slots every hour from 6am to 2pm were available when concessionaires could dive on Quarter-mile reef. In 2015/2016, the time slots were modified from 6am to 12pm and then again in 2016/2017 from 7am to 1pm, with Wednesdays closed to all diving. This system remains in force today.

evidence based approach

5 year research findings

Background

Spotted ragged-tooth sharks (Carcharias taurus) undertake an annual breeding migration up the east coast of South Africa, where after mating in Southern KwaZulu Natal, pregnant females move into the warmer waters of the iSimangaliso Marine Protected Area (iSimangaliso) in approximately October each year. The relatively warmer water temperatures in this region enhance early embryo development, with females spending approximately 4-6 months resting in the nearshore waters of iSimangaliso before moving back to the Eastern Cape to drop their pups. With this species being listed as Critically Endangered by the IUCN and inhabiting iSimangaliso during a vital part of their life cycle (i.e. gestation period), it is important that monitoring and management are strengthened to help ensure the optimal reproductive success of the species.

This long-term study aims to monitor the reef occupancy and movement trends of ragged-tooth sharks within iSimangaliso, whilst assessing the environmental drivers of such movements. A secondary objective is to monitor the possible effects of scuba diving on ragged-tooth shark congregations at Quarter-Mile Reef.

Methods

Snorkel surveys were conducted on all viable weather days to monitor shark numbers and record environmental variables on the two best-known aggregation sites, namely Quarter-Mile Reef and Raggie Reef, the latter is very close to Leven Point, 40 km south of Sodwana and is located in the iSimangaliso Offhore Wilderness Zone (IOWZ), where no recreational scuba diving is permitted.

Snorkel surveys were conducted on all viable weather days to monitor shark numbers and record environmental variables on the two best-known aggregation sites, namely Quarter-Mile Reef and Raggie Reef, the latter is very close to Leven Point, 40 km south of Sodwana and is located in the iSimangaliso Offhore Wilderness Zone (IOWZ), where no recreational scuba diving is permitted.

Remote Underwater Video (RUV) equipment was deployed on Quarter-Mile Reef and Raggie Reef to monitor shark numbers and, in the case of Quarter-Mile Reef, a popular dive site, to record diver behaviour. Raggie Reef has sharks present throughout the year, therefore the RUV is deployed for longer periods to monitor sharks at this site. As a result, far more images of sharks were captured and examined for photo-identification purposes.

results

Shark Diving – Reef Occupancy and Movement Trends (2019 -2023)

Gestation Phase: Movements of ragged-tooth sharks within the Park, are driven by the gestation phase of the females, i.e. “early”, “mid”, or “late”. The “early” phase is characterized by the arrival and fluctuations of high numbers of sharks at the study sites during December, followed by the “mid” gestation phase during January and February when the sharks are resting, and there is less fluctuation in numbers at each site. The “late” gestation phase, during March and April, sees more fluctuation in the numbers of sharks at each site, with many of the sharks being visibly pregnant.

Reef Carrying Capacity: Based on five seasons of monitoring, there appears to be an optimal reef carrying capacity, or group size of 15-20 sharks at each of the study sites. Peaks of 30 or more sharks are not sustained for longer than a few days, even at Raggie Reef which is a much larger reef structure than Quarter-Mile Reef.

Wave Height: Given the shallow depths of both sites (12-14m), high wave heights can produce a significant bottom surge. Using weather forecast data from windguru.com during the project period, there is good observational evidence to indicate that wave heights over two meters at both Quarter-Mile and Raggie Reef cause the majority of the sharks to vacate the reefs, with the sharks moving into nearby deeper water to presumably avoid the surge.  This only lasts for a day or two, with the sharks returning to the reef once the surge subsides.

Reef Closure/Opening Trends: Quarter-Mile Reef is systematically closed to scuba diving in mid-October before the bulk of the sharks arrive in December. The purpose of this closed period is to allow the sharks to arrive and settle without disturbance. During this period, shark numbers increase and stabilise. Once the sharks are settled, i.e. minimum of 5-10 sharks for 5 or more days, the reef is opened to diving on a roster system. The roster allows for a high amount of diving activity, specifically, one boat (up to 11 divers) every hour from 7 a.m.-1 p.m., 6 days a week. After diving activity begins, evidence obtained during this project has revealed that poorly trained dive leaders and, no code of conduct being followed, results in disturbance and relatively rapid disappearance of the sharks from this reef for the remainder of the season.

Conclusion: The 2022/2023 season showed very similar reef occupancy and movement trends to previous seasons, where sharks were adversely affected by the behaviour of divers on the reef. To remedy this, it is recommended that measures to improve diver behaviour be implemented, such as compulsory training in the code of conduct by Dive Masters of active Concessionaires, this system was previously put in place in 2003 by the dive concessions themselves, but has since fallen away.