Great White Shark Carcharodon Carcharias Research Articles

Seasonal occurrence and sexual segregation of great white sharks Carcharodon carcharias in Mossel Bay, South Africa

The seasonal occurrence and temporal sexual segregation of great white sharks Carcharodon carcharias have been widely documented in various temperate and sub-tropical waters across the globe. Yet, there is limited understanding of the relationship between the life stages and habitat use of C. carcharias, particularly in the Southern Cape. In this study, we investigated the population dynamics of C. carcharias in Mossel Bay, South Africa, between 2009 and 2013, using skipper logbooks and citizen research data obtained by a cage-diving vessel. A total of 3064 sharks, ranging in life history stages from young-of-the-year to subadult, were sighted during 573 trips. Juveniles dominated the sightings throughout the study, and there was marked sexual segregation, with females dominating the total sightings of sharks. C. carcharias were most abundant during the cooler, winter season, with females differing in abundance seasonally and males maintaining a low abundance throughout the year but peaking in the winter. In addition, sea surface temperature was the best indicator of C. carcharias presence. Abundance was greatest when vertical water visibility exceeded 3 m, with cloud cover influencing overall abundance negatively. Likely reasoning for the aggregation of C. carcharias in Mossel Bay includes the favourable conditions and abundance of food. Juvenile sharks may also utilise this area as a training ground to learn from larger conspecifics. This research demonstrates that information on population size and structure of C. carcharias can be obtained effectively through a compilation of logbook and citizen science data to assess and identify potential critical habitats in the quest to develop appropriate management strategies. This research also shows value in commercial cage-diving operations deriving international data sets needed to assess global populations of C. carcharias.

Using Citizen Science to Detect Rare and Endangered Species: New Records of the Great White Shark Carcharodon Carcharias off the Libyan Coast.

The presence of the great white shark (Carcharodon carcharias) in the Mediterranean Sea is well documented, but encounters with this species are rare and all assumptions about its spatial and temporal distribution are heavily relying on anecdotal observations. To date, only one record off the Libyan coast has been reported, raising the question if this species is underreported in these waters or simply represents a rare occasional transient. We utilised citizen science-sourced data to document the presence of the great white shark off the Libyan coast, and found six additional records for this species from the period between 2017 and 2020. Our study points out the need for scientific monitoring of this species along the Libyan coast to facilitate the establishment of effective conservation plans to protect this critically endangered species.

THE GREAT WHITE SHARK Carcharodon carcharias (LINNÉ, 1758) IN THE PLIOCENE OF PORTUGAL AND ITS EARLY DISTRIBUTION IN EASTERN ATLANTIC

Fossil great white shark Carcharodon carcharias has been recognized for the first time in Portugal near Marinha Grande in Pliocene sediments. This occurrence further broadens its already huge distribution. It is indeed the first Pliocene shark so far identified in Portugal. The great white shark is represented but by a single upper right lateral tooth lost after use from a ca. 4 m TL, adult individual. The presence is very much in agreement with all known data about Iberian Peninsula, where it really has never been found in Miocene units but becomes common in lower Pliocene levels in Spain. Although the evidence is typical, it is too scarce to allow much speculation on the species numerical importance. If however we take into account that no other shark teeth are known in the concerned sediments it can provisorily be accepted that its occurrence would be rather common. This new record for the Pliocene in Portugal underlines the closeness of the first known occurrences for the eastern Atlantic, both in its northern (as this is the case) and southern parts as shown by the referred Pliocene fauna of Farol das Lagostas, Angola.

On catches of low-latitude fish at Sakhalin coast in summer 2014

In summer 2014, catches of three tropical and subtropical fish species were registered at Sakhalin coast. The Japanese sea bass Lateolabrax japonicus was detected at Sakhalin coast for the first time, while the Japanese amberjack Seriola quinqueradiata was first detected in the Sea of Okhotsk waters sweeping the Sakhalin coast. The catch of the great white shark Carcharodon carcharias is the second confirmed case of this fish occurrence near the Sakhalin coast for the last 10 years.

A computer-aided framework for subsurface identification of white shark pigment patterns

Subsurface video footage can be used as a successful identification tool for various marine organisms; however, processing of such information has proven challenging. This study tests the use of automated software to assist with photo-identification of the great white shark Carcharodon carcharias in the region of Gansbaai, on the south coast of South Africa. A subsurface photo catalogue was created from underwater video footage. Single individuals were identified by using pigmentation patterns. From this catalogue, two images of the head for each individual were inserted into automated contour-recognition software (Interactive Individual Identification System Beta Contour 3.0). One image was used to search the database, the other served as a reference image. Identification was made by means of a contour, assigned using the software to the irregular border of grey and white on the shark's head. In total, 90 different contours were processed. The output provided ranks, where the first match would be a direct identification of the individual. The method proved to be accurate, in particular for high-quality images where 88.24% and 94.12%, respectively, were identified by two independent analysts as first match, and with all individuals identified within the top 10 matches. The inclusion of metadata improved accuracy and precision, allowing identification of even low-quality images.

The capture of a great white shark Carcharodon carcharias Linnaeus, 1758 (Carcharodontidae) in peter the Great Bay (Sea of Japan)

This paper reports on the first reliable capture of the Great White shark Carcharodon carcharias (length 126 cm, weight 16 kg) in Peter the Great Bay (Sea of Japan). Capture records of C. carcharias in the Far-Eastern seas of Russia are discussed.

Lévy flight and Brownian search patterns of a free‐ranging predator reflect different prey field characteristics

1. Search processes play an important role in physical, chemical and biological systems. In animal foraging, the search strategy predators should use to search optimally for prey is an enduring question. Some models demonstrate that when prey is sparsely distributed, an optimal search pattern is a specialised random walk known as a Lévy flight, whereas when prey is abundant, simple Brownian motion is sufficiently efficient. These predictions form part of what has been termed the Lévy flight foraging hypothesis (LFF) which states that as Lévy flights optimise random searches, movements approximated by optimal Lévy flights may have naturally evolved in organisms to enhance encounters with targets (e.g. prey) when knowledge of their locations is incomplete. 2. Whether free-ranging predators exhibit the movement patterns predicted in the LFF hypothesis in response to known prey types and distributions, however, has not been determined. We tested this using vertical and horizontal movement data from electronic tagging of an apex predator, the great white shark Carcharodon carcharias, across widely differing habitats reflecting different prey types. 3. Individual white sharks exhibited movement patterns that predicted well the prey types expected under the LFF hypothesis. Shark movements were best approximated by Brownian motion when hunting near abundant, predictable sources of prey (e.g. seal colonies, fish aggregations), whereas movements approximating truncated Lévy flights were present when searching for sparsely distributed or potentially difficult-to-detect prey in oceanic or shelf environments, respectively. 4. That movement patterns approximated by truncated Lévy flights and Brownian behaviour were present in the predicted prey fields indicates search strategies adopted by white sharks appear to be the most efficient ones for encountering prey in the habitats where such patterns are observed. This suggests that C. carcharias appears capable of exhibiting search patterns that are approximated as optimal in response to encountered changes in prey type and abundance, and across diverse marine habitats, from the surf zone to the deep ocean. 5. Our results provide some support for the LFF hypothesis. However, it is possible that the observed Lévy patterns of white sharks may not arise from an adaptive behaviour but could be an emergent property arising from simple, straight-line movements between complex (e.g. fractal) distributions of prey. Experimental studies are needed in vertebrates to test for the presence of Lévy behaviour patterns in the absence of complex prey distributions.

Insights Using a Molecular Approach Into the Life Cycle of a Tapeworm Infecting Great White Sharks

The great white shark Carcharodon carcharias Linnaeus, 1758 is a versatile and fierce predator (and responsible for many shark attacks on humans). This apex predator feeds on a wide range of organisms including teleosts, other elasmobranchs, cephalopods, pinnipeds, and cetaceans. Although much is known about its diet, no trophic links have been empirically identified as being involved in the transmission of its tapeworm parasites. Recently, the use of molecular tools combined with phylogenetics has proven useful to identify larval and immature stages of marine tapeworms; utilization of the technique has been increasing rapidly. However, the usefulness of this approach remains limited by the availability of molecular data. Here, I employed gene sequence data from the D2 region of the large subunit of ribosomal DNA to link adults of the tapeworm Clistobothrium carcharodoni Dailey and Vogelbein, 1990 (Cestoda: Tetraphyllidea) to larvae for which sequence data for this gene are available. The sequences from the adult tapeworms were genetically identical (0% sequence divergence) to those available on GenBank for "SP" 'small' Scolex pleuronectis recovered from the striped dolphin (Stenella coeruleoalba) and Risso's dolphin (Grampus griseus). This study is the first to provide empirical evidence linking the trophic interaction between great white sharks and cetaceans as a definitive route for the successful transmission of a tetraphyllidean tapeworm. Using the intensity of infection data from this shark and from cetaceans as proxies for the extent of predation, I estimate that this individual shark would have consumed between 9 to 83 G. griseus , fresh, dead, or both, in its lifetime.

The Persian/Arabian Gulf’s sole great white shark Carcharodon carcharias (Lamniformes: Lamnidae) record from Kuwait: misidentification of a sandtiger shark Carcharias taurus (Lamniformes: Odontaspididae)

Records of the great white shark Carcharodon carcharias (Linnaeus) (Lamniformes: Lamnidae) in the Persian/Arabian Gulf (hereafter referred to as “The Gulf”) are limited to a single report from Kuwait, in the northwest Gulf, which has subsequently been noted in key references (e.g. Compagno, 2001). Khalaf (1987) recorded C. carcharias based on an observation of a mounted specimen in Kuwait Science and Natural History Museum on a visit there in March 1987. The specimen is reported as being a female C. carcharias of 3m in length, caught off Kuwait’s coast and supplied to the museum on the 14th of April 1984. A black and white photograph of the anterior portion (from just posterior of the pelvic fins) was included in Khalaf’s account (Fig. 1 here), but no measurements or morphological data were presented.

Incidence of organochlorine pesticides in muscle and liver tissues of South African great white sharks Carcharodon carcharias

Because of the environmental persistence and biomagnification of DDT and other organochlorine pesticides, marine apex predatory species such as polar bears and toothed whales have been shown to accumulate significant concentrations (Muir et al., 1999). Few studies have examined concentrations in marine predators closer to the tropics. An apex predator that frequents tropical environments and also preferentially feeds upon marine mammals is the great white shark Carcharodon carcharias. Gut content analyses of immature white sharks taken in large-mesh gillnets that provide protection against shark attack at the more popular beaches in KwaZuluNatal on the East Coast of South Africa have indicated that 40.8% of the total diet by weight -was of marine mammal origin (Cliff et al., 1989). Tricas and McCosker (1984) commented that white sharks over 2.5 m tend to target marine mammals. This was supported by Cliff et al. (1989), who showed a higher incidence of marine mammals by frequency of occurrence, by mass and by number in the gut contents of larger sharks with a higher preference toward cetaceans over pinnipeds (Tricas and McCosker, 1984; Cliff et al., 1989). Previous studies examining organochlorine pesticides in blubber of com-

A comparison of the shark control programs of New South Wales and Queensland (Australia) and KwaZulu-Natal (South Africa)

The shark control programs of New South Wales (NSW), Queensland and KwaZulu-Natal (KZN) are compared in an attempt to determine whether the fishing effort applied in the KZN program could be reduced. The stated mechanism in all three programs is to reduce shark numbers, and thereby the probability of an encounter between a shark and a bather. Large-mesh ( 50–60 cm stretched) gill nets are used in each program, and in Queensland these are supplemented by baited drumlines. The number of standard ( 100 m net) net-days per protected (meshed) bathing area per month is about 26 in NSW, 57 in Queensland and 192 in KZN. There is a four-month closed season (i.e. no control measures) in winter in NSW, a six-week closed season at some Queensland beaches and no closed season in KZN. Despite these differences, the apparent successes of the programs in reducing the total number of shark attacks recorded at meshed beaches are impressive and comparable. The same shark species are believed to have been responsible for most of the attacks in the three regions, these being the great white shark Carcharodon carcharias, the bull shark Carcharhinus leucas and the tiger shark Galeocerdo cuvier. After comparing factors such as the nearshore physical environment and trends in shark catch and catch rate, it is concluded that there is a case for reducing the number of nets in KZN.

Sharks caught in the protective gill nets off Natal, South Africa. 2. The great white sharkCarcharodon carcharias(Linnaeus)

A total of 591 great white sharks Carcharodon carcharias was caught between 1974 and 1988 in the gill nets which are maintained along the Natal coast to protect bathers from shark attack. The species represented 2,7 per cent of the total catch of sharks for the period 1978–1988 and the mean catch rate was 1,0 shark·km-net−1·year−1. Specimens ranged in size from 131 to 348 cm precaudal length, with a mode of 206–210 cm for females and 216–220 cm for males. None was mature, and the sex ratio was 1 male to 1,4 females. Catch rates were highest in the southernmost nets, with a smaller peak in the extreme north. Catches peaked in midwinter, those in the warmer, northern region lagging 1–2 months behind those in the cooler southern waters. The relationship between catches and water clarity and temperature was tenuous. Elasmobranchs were the most important prey item, occurring in 41,1 per cent of stomachs containing food, followed by teleosts at 34,7 per cent and marine mammals at 29,0 per cent, although marine ...