Surveys of white sharks (Carcharodon carcharias) off bathing beaches in Algoa Bay, South Africa

2013 ◽  
Vol 64 (6) ◽  
pp. 530 ◽  
Author(s):  
M. L. Dicken ◽  
A. J. Booth
Keyword(s):  
South Africa ◽  
Logistic Regression ◽  
Barometric Pressure ◽  
White Shark ◽  
Hurdle Model ◽  
Carcharodon Carcharias ◽  
Key Informant ◽  
Young Of The Year ◽  
Log Normal ◽  
Management And Conservation

The present study provides information on the existence of a possible inshore nursery area for white sharks (Carcharodon carcharias) in Algoa Bay, South Africa. In total, 43 flights were conducted, using a Robinson R22 helicopter, between October 2010 and March 2012. A total of 50 white sharks was sighted, with a maximum sighting rate of seven sharks per hour in October 2010. The majority (96.0%) of sharks observed were less than 2.5 m in length, immature and sighted between October and March (98.0%). A hurdle model, comprising a logistic regression to model presence–absence and a log-normal generalised linear model for abundance showed that water temperature and barometric pressure explained the sightings of sharks, peaking in mid-December. The sighting of sharks was best explained by barometric pressure, month and year. A total of 58 white shark catches was recorded from key informant interviews with shore anglers between July 2009 and December 2011. Sharks ranged in size from 1.5 to 2.5 m in total length, with young-of-the-year sharks (<1.75 m) accounting for 69.0% of the catch. Defining key habitats for young-of-the-year and juveniles is critical for the management and conservation of white sharks worldwide.

First observations of young of the year and juvenile great white sharks (Carcharodon carcharias) scavenging from a whale carcass

2008 ◽  
Vol 59 (7) ◽  
pp. 596 ◽  
Author(s):  
M. L. Dicken
Keyword(s):  
South Africa ◽  
Foraging Behaviour ◽  
Scientific Literature ◽  
Carcharodon Carcharias ◽  
Great White Shark ◽  
Young Of The Year ◽  
Management And Conservation ◽  
Term Management ◽  
Insight Into

Observations of great white sharks (Carcharodon carcharias) scavenging from cetacean carcasses are rare and have only been reported in the scientific literature for large (>3.5 m total length (TL)) individuals. Between 13 October and 25 November 2006, young of the year and juvenile great white sharks were observed scavenging from the carcass of a humpback whale (Megaptera novaeangliae) in Algoa Bay, South Africa. Although more than one shark scavenged from the carcass, simultaneous feeding was not observed. The sharks showed a clear preference for soft tissue at sites along the mouth of the carcass. Protective ocular rotation was rarely observed and none of the sharks exhibited palatoquadrate protrusion while feeding. These observations provide a new insight into the foraging behaviour of young of the year and juvenile great white sharks. The prevalence of small great white sharks (1.5 m TL) and the absence of any individuals greater than 3.65 m TL suggest that Algoa Bay may function as a nursery area for great white sharks in South Africa. This information is crucial not only to improve our understanding of great white shark biology, but also for their long-term management and conservation in South Africa.

scholarly journals Antibiotic sensitivity of bacteria isolated from the oral cavities of live white sharks (Carcharodon carcharias) in South African waters

2019 ◽  
Vol 115 (11/12) ◽  
Author(s):  
Enrico Gennari ◽  
Alison A. Kock ◽  
Malcolm J. Smale ◽  
Alison Towner ◽  
Nasreen Khan ◽  
...  
Keyword(s):  
South Africa ◽  
Antibiotic Resistance ◽  
South African ◽  
Antibiotic Sensitivity ◽  
White Shark ◽  
Shark Species ◽  
Apex Predators ◽  
Carcharodon Carcharias ◽  
Bacterial Microbiota ◽  
Carbapenem Antibiotic

The white shark (Carcharodon carcharias) is responsible for 49% of shark-related injuries in South Africa, yet no information currently exists on the composition or antibiotic resistance of bacteria hosted by these apex predators in South African waters. This study aimed to address this gap by sampling the bacteria present in the oral cavities of 28 live C. carcharias along South Africa’s southern coastline. The antibiotic resistance of the range of microbiota was also assessed using antibiotic disc diffusion tests. A total of 51 strains from at least 20 species of bacteria were isolated from the oral cavities of C. carcharias. Of these strains, the most common bacteria present were Serratia spp., Proteus vulgaris and Vibrio alginolyticus. The overall antibiotic resistance was relatively higher in this study than that reported for bacterial microbiota sampled from other shark species. Results indicate that the combination therapy of imipenem (carbapenem antibiotic) and vancomycin (glycopeptide antibiotic) might be the most parsimonious option to effectively treat infections resulting from white shark bites, particularly in South Africa. It is hoped that, in addition to assisting medical professionals to treat shark bite victims, these findings enhance the understanding of the microbial communities present in large coastal predators and their surrounding environments.

Concordance of genetic and fin photo identification in the great white shark, Carcharodon carcharias, off Mossel Bay, South Africa

2009 ◽  
Vol 156 (10) ◽  
pp. 2199-2207 ◽  
Author(s):  
Chrysoula Gubili ◽  
Ryan Johnson ◽  
Enrico Gennari ◽  
W. Hermann Oosthuizen ◽  
Deon Kotze ◽  
...  
Keyword(s):  
South Africa ◽  
White Shark ◽  
Carcharodon Carcharias ◽  
Photo Identification ◽  
Great White Shark

predatory behaviour of white sharks (carcharodon carcharias) at seal island, south africa

2005 ◽  
Vol 85 (5) ◽  
pp. 1121-1135 ◽  
Author(s):  
r. aidan martin ◽  
neil hammerschlag ◽  
ralph s. collier ◽  
chris fallows
Keyword(s):  
South Africa ◽  
Success Rate ◽  
White Shark ◽  
Predatory Fish ◽  
Success Rates ◽  
Carcharodon Carcharias ◽  
Predatory Behaviour ◽  
Video Footage ◽  
Anterior Teeth ◽  
Fur Seals

between 1997 and 2003, there were 2088 natural predations by white sharks (carcharodon carcharias) on cape fur seals (arctocephalus pusillus pusillus) and 121 strikes on towed seal-shaped decoys were documented from observation vessels at seal island, south africa. white sharks at seal island appear to selectively target lone, incoming young of the year cape fur seals at or near the surface. most attacks lasted <1 min and consisted of a single breach, with predatory success rate decreasing rapidly with increasing duration and number of subsequent breaches. a white shark predatory ethogram, composed of four phases and 20 behavioural units, is presented, including four varieties of initial strike and 11 subsequent behaviour units not previously defined in the literature. behaviour units scored from 210 predatory attacks revealed that, for both successful and unsuccessful attacks, polaris breach was the most commonly employed initial strike, while surface lunge was the most frequent second event, closely followed by lateral snap. examination of video footage, still images, and tooth impressions in decoys indicated that white sharks at seal island bite prey obliquely using their anterolateral teeth via a sudden lateral snap of the jaws and not perpendicularly with their anterior teeth, as previously supposed. analysis of white shark upper tooth morphology and spacing suggest the reversed intermediate teeth of white sharks occur at the strongest part of the jaw and produce the largest wound. white shark predatory success at seal island is greatest (55%) within one hour of sunrise and decreases rapidly with increasing ambient light; the sharks cease active predation on seals when success rate drops to ±40%; this is the first evidence of cessation of foraging at unproductive times by any predatory fish. at seal island, white shark predatory success is significantly lower at locations where frequency of predation is highest, suggesting that white sharks may launch suboptimal strikes in areas of greatest intraspecific competition; this is the first evidence of social influence on predation in any elasmobranch. idiosyncratic predatory behaviours and elevated success rates of known individual white sharks at seal island suggest some degree of trial-and-error learning. a hypothetical decision tree is proposed that models predatory behaviour of white sharks attacking cape fur seals at the surface.

Sign in / Sign up

Export Citation Format

Share Document