Great white sharks in the north east Pacific live in shallow coastal waters off of Central California about half of the year. Scientists were surprised by the amount of time spent in shallow water because great white shark attacks on humans are uncommon. Pinnepeds - sea lions and seals - are the great white shark's primary food source in the central California waters. People occasionally get in trouble when they get close to feeding areas. Outside of feeding areas, great white sharks will even pose for photographers.
By FishOutofWater
A just published study based on 8 years of tracking 179 great white sharks in the north east Pacific shows that the sharks are a distinct group that has apparently been separated from south Pacific sharks since the end of the ice age. Most of the sharks make a yearly migration beginning in early winter from California towards the Hawaiian islands. Many sharks stay in an area called the "Great White Shark Cafe" in mid ocean about halfway between California and the islands.
By FishOutofWater
Great white sharks apparently dive for food in the half of the year they live in the open ocean. Modern tracking devices that sharks were tagged with recorded the amount of diving activity which is shown in half monthly increments. Sharks start arriving at the "cafe" in early winter but deep diving activity starts in mid March and ends in late July when sharks migrate back to central California.
By FishOutofWater
Great white sharks have never been observed mating in California waters. They apparently mate on "spring break" and "summer vacation" in the waters east of Hawaii.
Mating is likely to occur where males and females overlap consistently. Observed overlap was minimal near Hawaii but occurred at coastal sites and at the Cafe´ (figures 3 and 4). No direct or indirect evidence of copulation at North American coastal sites has ever been reported, despite decades of observation (Anderson & Pyle 2003; Domeier & Nasby-Lucas 2008). Reported incidental captures of neonates in the Southern California Bight peak between July and October (mean recorded TL during those months was 1.41, 1.65, 1.69 and 1.73 m respectively)(Klimley 1985) suggesting that parturition occurs there during spring and summer (Francis 1996).
If C. Carcharias gestation period is greater than 12 months and likely around 18 months as has been proposed (Francis 1996; Mollet et al. 2000), copulation would have to occur sometime between March and August. This coincides with the peak period of activity in the Cafe´, when virtually all males still bearing PAT tags occurred there (figures 3 and 4). If mating occurs in the Cafe´, periodic segregation could reflect refuging by females from costly mating activities (Wearmouth & Sims 2008).
Additionally, some tagged females remained offshore (four out of eight) or in the Southern California Bight nursery habitat (one out of eight) through August and as late as November (figures 3 and 4) consistent with previous observations that females may only return to coastal aggregation sites every second year owing to an extended reproductive cycle (Anderson & Pyle 2003; Domeier & Nasby-Lucas 2007).
While it's apparent that great white sharks forage for food in Hawaiian waters, attacks by great white sharks are extremely uncommon there. Great white sharks in Hawaiian waters show no interest in feeding on humans. The vilification of great white sharks in "Jaws" is unscientific Hollywood fear mongering.
In reality, great whites will give a toothy smile for the camera and let the photographer post the photos on the internet.
By FishOutofWater
The north east Pacific great white sharks are an isolated population that needs to be protected in a coordinated manner by the governments of the USA and Mexico. They are magnificent in their own right, while they pose little threat to humans.
Our findings show that NEP white sharks form a demographically isolated population with clearly defined spatial demarcation. The geographical isolation revealed from electronic tagging coupled with significant genetic (mtDNA) divergence evident from monophyletic clade structure indicates that NEP sharks, particularly females, are isolated from previously studied populations in the South Indo-Pacific, specifically ANZ and SA. The highly predictable seasonal distribution of NEP white sharks including repeated homing to and focus at a network of key coastal hotspots highlights where future population assessment and monitoring can be effectively conducted within US territorial waters. These results further emphasize the need for coordinated ocean management between the USA and Mexico.
Humans threaten great white sharks. Great white sharks don't threaten us.
By FishOutofWater