Natality vs Mortality of Great White Sharks

Natality vs Mortality of Great White Sharks

1. Natality

   • Hard to determine due to the Inaccessibility of the specie
   • Sexual maturity
     • Juvenile
     • Subadult
     • Adult
   • Aplacental vivipary
   • They are not embryophagus
   • Mating probably occurs between spring- summer
   • Gestation period unknown
   • Life time: 70 years in average

2. Mortality

   • Shark attacks on humans
   • GIll netting program (South Africa)
     • 40 km of nets, 1354 sharks catched per year (in average)
       • 39 white sharks
   • Fishing = overexploitation
   • Serious decline in shark population seen since 1992
   • Commercial fishing
   • Provoked and un provoked attacks
   • Reputation

3. Great White Sharks: The Biology of Charcharodon Charcharias

   • Main objectives of the book
     • -Improve the reputation of the Sharks
     • Make Five Expeditions
     • Tag as Many White Sharks as Possible
     • Provide a long term assesment of population dynamics
     • Protect the species
     • Create Laws that prohibit shark fishing in south california, south australia and south africa and create conservation programs world wide
     • show a Full detail of the Great white shark Biology
   • Main results a conclusions from the book
     • Results
       • Shak biology and behavior studied
       • 73-94 Sharks tagged
       • Recorded interactions of humans and sharks, fishing, tagging attacks etc...
       • successful efort to protect white shark in californian and south african waters
     • Main conlusions
       • Fishing mortality was assumed to be constant
       • Rarity of species
       • Great white Sharks are an endangerde species, Status: Vulnerable
       • Myths still preveal
       • Key organism for ecological balance
   • Chapters Used ( the Chapters are cientific papers with an unique theme about Great white sharks
     • Chapter 13: Reproduction in the male White shark ( Pag 131)
     • Chapter 14: Pregnant white sharks and full-term embryos from japan (Pag 139)
     • Chapter 15: Observations on a pregnant white shark with a review of reproductive biology (Pag 157)
     • Chapter 36: First estimates of mortality and population size on the south african coast ( Pag 393)
     • Chapter 37 : Population Dynamics of white sharks in spencer gulf, South australia (Pag 401)
     • Chapter 45: More rare than dangerous: a case study of white shark conservation in california (Pag 481)
   • General Methods from the book and it´s papers
     • methodology of Clark and Von Schmidt, And Pratt
     • Lateral or ventral incision
     • tagging, shark capture, nets
     • Petersen estimate
     • Baranov catch equation
     • population size determined by Petersen estimate