Behavior of Cape fur seals (Arctocephalus pusillus pusillus) in relation to temporal variation in predation risk by white sharks (Carcharodon carcharias)around a seal rookery in False Bay, South Africa

2015 ◽  
Vol 31 (3) ◽  
pp. 1118-1131 ◽  
Author(s):  
Alta De Vos ◽  
M. Justin O'Riain ◽  
Michael A. Meyer ◽  
P. Gideon H. Kotze ◽  
Alison A. Kock
Keyword(s):  
South Africa ◽  
Temporal Variation ◽  
Predation Risk ◽  
Carcharodon Carcharias ◽  
Fur Seals

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.

Behavior of Cape fur seals (Arctocephalus pusillus pusillus) in response to spatial variation in white shark (Carcharodon carcharias) predation risk

2015 ◽  
Vol 31 (3) ◽  
pp. 1234-1251 ◽  
Author(s):  
Alta De Vos ◽  
M. Justin O'Riain ◽  
Michael A. Meÿer ◽  
P. Gideon. H. Kotze ◽  
Alison A. Kock
Keyword(s):  
Spatial Variation ◽  
Predation Risk ◽  
White Shark ◽  
Carcharodon Carcharias ◽  
Fur Seals

scholarly journals Shark–Cetacean trophic interaction, Duinefontein, Koeberg, (5 Ma), South Africa

2015 ◽  
Vol Volume 111 (Number 11/12) ◽  
Author(s):  
Romala Govender ◽  
Keyword(s):  
South Africa ◽  
Cause Of Death ◽  
West Coast ◽  
Trophic Interaction ◽  
The West ◽  
Carcharodon Carcharias ◽  
Inverted Position ◽  
Bite Marks ◽  
Shark Teeth ◽  
Long Time

Abstract This study forms part of a larger project to reconstruct the Mio-Pliocene marine palaeoenvironment along South Africa’s west coast. It documents the shark–cetacean trophic interaction during the Zanclean (5 Ma) at Duinefontein (Koeberg). The damage described on the fragmentary cetacean bones was compared with similar damage observed on fossils from Langebaanweg, a Mio-Pliocene site on the west coast of South Africa, and data present in the literature. This comparison showed that the damage was the result of shark bites. The state of preservation makes it difficult to determine if the shark bite marks were the cause of death or as a result of scavenging. The presence of the bite marks on the bone would, however, indicate some degree of skeletonisation. Bite marks on some cranial fragments would suggest that the cetacean’s body was in an inverted position typical of a floating carcass. The preservation of the material suggests that the bones were exposed to wave action resulting in their fragmentation as well as abrasion, polishing and rolling. It also suggests that the cetacean skeletons were exposed for a long time prior to burial. The morphology of the bites suggests that the damage was inflicted by sharks with serrated and unserrated teeth. Shark teeth collected from the deposit include megalodon (Carcharodon megalodon), white (Carcharodon carcharias) as well as mako (Isurus sp. and Cosmopolitodus hastalis) sharks, making these sharks the most likely predators/scavengers.

scholarly journals Coastal swimming patterns of white sharks (Carcharodon carcharias) at Mossel Bay, South Africa

2009 ◽  
Vol 85 (3) ◽  
pp. 189-200 ◽  
Author(s):  
Ryan Johnson ◽  
Marthán N. Bester ◽  
Sheldon F. J. Dudley ◽  
W. Herman Oosthuizen ◽  
Michael Meÿer ◽  
...  
Keyword(s):  
South Africa ◽  
Carcharodon Carcharias
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