Carcharodon carcharias

Great White Shark

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Great White Shark

 

Description

This mighty shark is often mistakenly thought of as the most voracious predator of the seas, and even has a reputation as a ferocious man-eater, something that sadly has been hugely exaggerated by the media. Their powerful body is supported by a cartilaginous skeleton (as opposed to the bone skeleton of most other vertebrates), is streamlined for efficient movement through the water, and has a pointed snout, two large, sickle-shaped pectoral fins and a large triangular first dorsal fin. The mouth is armed with an array of sharply pointed, serrated teeth; indeed the generic name is derived from the Greek word carcharos for ragged and odon for tooth. These sharks are grey or bronze on the upper surface of the body and are white underneath. They have an acute sense of smell and are able to sense electric fields through sensors in the snout.

Geography

Cosmopolitan, mostly amphitemperate. Western Atlantic: Newfoundland, Canada to Argentina; also north Gulf of Mexico, Bahamas, Cuba and Lesser Antilles (Ref. 26938). Eastern Atlantic: France to South Africa, including the Mediterranean. Indian Ocean: Red Sea, Seychelles, South Africa; also Reunion and Mauritius (Ref. 33390). Western Pacific: Siberia to New Zealand and the Marshall Islands; also south Australia (Ref. 26938). Central Pacific: Hawaii. Eastern Pacific: Alaska to Chile.

Ecosystem

Great white sharks are primarily a coastal and offshore inhabitant of insular and continental shelves (Aidan Martin, 2003). Great white sharks have been known to breach the surface and have also been found at depths of 1,875 meters (Dale, 2008). They seem to prefer waters with sea surface temperatures of 59 to 72°F (Aidan Martin, 2003). They can be found on the following coastlines: California to Alaska, the east coast of the United States, coastal Gulf of Mexico, Hawaii, coasts of South America, South Africa, Australia (except the north coast), New Zealand, Mediterranean Sea, West Africa to Scandinavia, Japan, and the eastern coastline of China to Russia (Dale, 2008).

Conservation

Great white sharks are rare throughout their range. This, coupled with their low reproductive rates and persecution by humans means that the IUCN considers them vulnerable. Hunting and bycatch in commercial fisheries exerts significant pressure on great white shark populations and newer estimates may suggest that great white sharks should be considered endangered.

 

Threats

Major Threats
Under various synonyms (maneater, white death), the Great White Shark has long been a focus for negative media attention, generated by its sometimes lethal interactions with humans. As a consequence of this typically exaggerated threat to human safety and an almost legendary ?Big Fish? status, the species is targeted as a source for sports-fishing, commercial drumline trophy-hunting (for jaws, teeth and even entire specimens preserved), sporadic human consumption or merely as the piscine whipping-boy of individuals pandering to shark attack paranoia. All of these activities have greatly increased since the ?JAWS? media phenomenon of the mid 1970s, not only to the detriment of C. carcharias but also in encouraging targeting of other, less high-profile species. Nowhere is the Great White Shark abundant and productive enough to sustain long-term directed fisheries; the majority of annual captures worldwide being made incidentally through commercial fisheries operating longlines, setlines, gillnets, trawls, fish-traps and other gear. The Great White Shark is ensnared throughout the water column in nearshore fisheries but, notably, is rarely represented in the elasmobranch bycatch of offshore oceanic pelagic fisheries (unlike Shortfin Mako (Isurus oxyrinchus) and Porbeagle (Lamna nasus)). The Great White Shark is vulnerable to capture trauma and may be killed or has limited survivorship after capture. Great White Sharks are curious and readily approach boats, scavenge from fishermens? nets or longlines and devour hooked fish taken by rod-and-line or swordfish harpoon. This vulnerable propensity often results in either their own accidental entrapment or deliberate killing by commercial fishermen. In certain regions the Great White Shark has traditionally been viewed negatively as manifesting a costly interference to fisheries, although some fishers appreciate it for its role in eating pinnipeds that devour their catches. This species is unquestionably vulnerable to directed exploitation such as sports fisheries, the curio trade, the oriental shark-fin trade and even the public aquarium trade. The overall, long-term impact of these causes of mortality upon regional populations, coupled to those caused through indirect fishery captures or protective beach meshing, is probably detrimental. The removal of even a few individuals apparently has very tangible effect at discrete localities (such as the Farallon Islands, California, based upon observations following the cull of four local sharks in 1984 (Ainley et al. 1985)). Habitat degradation (development, pollution and overfishing) also threatens this species and may largely exclude it from areas, perhaps traditionally utilised for feeding or as nurseries, where it was historically much more abundant. Great White Sharks have been sought as the ultimate species to display in large public oceanaria, but with poor survivorship so far. Directed fishery exploitation of Great White Sharks is primarily undertaken with the aim of trading its teeth and jaws as trophies or curios and its fins for the oriental fin trade. In South Africa offers of US$20,000?$50,000 have been made for great white shark jaws and US$600? $800 for individual teeth. Apart from their size, Great White Shark products in the form of curios and fins are boosted in value because of notoriety. A fin-set from a large great white shark may be valued at over US$1,000. Unfortunately, as with rhino horns and elephant tusks, the high value of Great White Shark products encourages poaching, clandestine trade and flouting of protective laws (Compagno 2001). Comparative data of catch-rates and CPUE are sketchy or lacking for most of the Great White Shark?s range, although some figures are available from select regions. Observations of game fishery captures in south-east Australia between 1961?1990 indicate a catch-ratio from 1:22 in the 1960s, declining to 1:38 in the 1970s and 1:651in the 1980s (Pepperell 1992), suggesting a possible decline in abundance. South Australian game-fishing catches from 1980?1990 averaged 1.4 sharks per year and has declined since the 1950s, possibly through a reduction in effort (Bruce 1992). Sydney game fishing catches have ranged from 0?17 between 1950?1980, with no significant trend. Commercial bycatches off Australia are suspected to be the largest cause of mortality to Australian Great White Sharks, although without any data to currently substantiate this claim (J.D. Stevens and B. Bruce pers. comm.).

Recent tagging off South Australia (70?90 animals tagged) has demonstrated a 4?6% recapture rate (Stevens and Bruce pers. Comm.), which may be considered cause for concern. Approximately 40% of 126 Great White Sharks tagged at Dyer Island or Struisbaai, South Africa, between 1992?94 were resighted (Compagno unpubl.). Both the Australian and African research demonstrates at least short-term residency and site-affinity with some pronounced seasonality, coupled to more irregular nomadicity. Off the eastern USA, NMFS statistics from 1965?1983 show a decline from 1:67?1:210 (Casey and Pratt 1985), suggesting a possible decline in abundance. Data from beach meshing programmes in NSW and Queensland show a gradual and irregular decline in CPUE since the 1960s (J.D. Stevens and B. Bruce pers. comm.) whilst trends in KwaZulu-Natal meshing programmes are variable and less clear, but essentially downwards. Other indices of catch-rates are available from: California, between 1960?1985 as 0?14 sharks per year (mean 3.2, Klimley 1985), KwaZulu-Natal, between 1974?1988 as 22?61 sharks per year (Cliff et al. 1989) and the Central Mediterranean Sea (Sicilian Channel), between 1950? 1994 as 0?8 sharks per year (mean 2.2, Fergusson unpubl.). We presently have no complete data for Japan, New Zealand or Chile. In other areas, catches are much more nominal and very sporadic (e.g., Brazil, Hawaii).

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