Cape Cod White Shark Predation Study

About North Atlantic White Sharks

North Atlantic white shark at the water's surface image
male great white shark image
North Atlantic white shark spyhopping image
male great white shark image

The great white shark or Carcharodon carcharias is the largest predatory shark, and until recently, was rare in the western North Atlantic. This apex predator is crucial in maintaining a healthy marine ecosystem, and after decades of declines, appears to be in a state of recovery. As the top of the food chain, white sharks help to control populations of species such as the growing aggregations of grey seals (Halichoerus grypus) found in this region.

The resurgence of white sharks in the western North Atlantic is likely due to conservation efforts such as federal protection established in 1997, as well as increased availability of prey, perhaps most notably the grey seal. The movie “Jaws” seemed to have a profound impact in the species decline in this region, potentiating a pervasive public reputation that white sharks are a mindless eating machines.

We now know, however, that white sharks are very careful and intelligent predators, and there is perhaps no better example than the white sharks found in the western North Atlantic. The sharks here are “wild” white sharks and very elusive - they almost always shy away from human interaction. As a result, they are very difficult to study, and do not respond to the usual methods to attract them such as chumming.

Since these sharks are wild and naive to humans and the region, the opportunity to study their predatory behavior in this unique context is yielding a wealth of new information, as well as challenging some presently held beliefs. For instance, some of the sharks demonstrating seal predatory behavior off Cape Cod are smaller than previously recognized as the accepted size range known to hunt seals. The data is revealing a careful, thoughtful apex predator, powerful and deadly when needed, but far in contrast to antiquated perceptions.

Interesting White Shark Facts:

  • Lifespan may be 70 years or more
  • White sharks are “warm-blood” or endothermic maintaining a temperature higher than the environment
  • The average size range in this region appears to be 12 to 15 feet, but considerably smaller and larger sharks are seen, with some 18 feet or greater
  • White sharks are one the few marine animals to frequently lift its head above the waterline to look at objects, a technique known as spy-hopping
  • Basking sharks (Cetorhinus maximus) swimming at the surface are often misidentified as white sharks in this region
  • White sharks are slow to reproduce and were thought to reach sexual maturity around 15 years, but new data suggests they actually may mature closer to 30 years
  • White sharks have an eleven-month gestation with the spring and summer the likely seasons for delivery
  • White sharks are listed as a vulnerable species on the IUCN Red List of Threatened Species and included in Appendix II of CITES
  • Humans are not considered food and most accidents are the result of sharks mistaking people, such as surfers, for normal prey items. Nonetheless, white sharks are responsible for the greatest number of fatal unprovoked attacks on humans