Topic 5: Why Sharks attack? Flashcards
What negative event tends to happen after a human is “attacked”(encountered) by a shark?
- a culling of sharks
Why is calling it shark attack potentially bad? Alternative?
- because it places a negative stigma on sharks
- shark encounter ?
L> incident ?
Media Impacts:
- The effect media (news, movies etc) has on the population’s view of shark attacks has generally been?
-negative
Media Impacts:
- ____ theory and the effects of _____ syndrome explains how the media does what?
- cultivation
- mean world
- how the media affects a [erson’s view of the world
Media Impacts:
- Cultivation Theory ?
- is a social theory which examines the long term effects of television
Media Impacts:
- Cultivation Theory: The primary proposition of the cultivation theory states??
- that the more time people spend living in the television world, the more likely they are to believe social reality portrayed on television
Media Impacts:
- Cultivation Theory
L> cultivation leaves people with?
- a misconception of what is true in our world
Media Impacts:
- Mean world syndrome?
- a term coined by George Gerbner to describe a phenomenon whereby violence related content of mass media makes viewers believe that the world is more dangerous than it actually is.
- mean world syndrome is one of the main conclusions of cultivation theory.
ex: think of the african killer bee’s…mass hysteria
- mean world syndrome is one of the main conclusions of cultivation theory.
ISAF stands for what?
- The International Shark Attack Files
The International Shark Attack Files (ISAF):
- It is the longest running database on?
- shark attacks, has a long term scientifically documented database containing information on all known shark attacks and is the only globally comprehensive, scientific shark attack database in the world.
- **all the diagrams in this topic are from it!
The International Shark Attack Files (ISAF):
- World wide about __-___ shark attacks annually. Most recent was on ____ in ____. Results in about _-__ deaths.
- 70 to 100
- Feb. 2014, Austrailia
- 5-15 deaths (most attacks are done by small sharks)
The International Shark Attack Files (ISAF):
- Are all attacks reported?
- nope
L> tourism reasons…
The International Shark Attack Files (ISAF):
- Are attacks increasing?
- attacks going up each decade
L> more people in the water may be why! (more recreational)
Unprovoked shark attack trends worldwide(N=2238): Y= number of attacks, X= decade.
L> explain the graph
- attacks are going up over time.. as stated are there more people in the water or just more reporting going on?
- *more people traveling
- increased recreational water based activities
- larger populations
- *1900s-2000s
Worldwide unprovoked shark attacks and rate of fatality 1900-2009: Y= number of unprovoked shark attacks, percent fatal
X= decade
- Explain it!
- while increased incidents, fatalities decreased
- probably due to better medical aid over time
- reflective of how many sharks we have culled
L> aka not as many sharks left in the water as there use to be!
Unprovoked shark attacks in the world and USA 1960-2013 (N=2074):
- Y=number of attacks
- X= time…1960-2013 (USA attacks vs Other countries)
- *Explain it!
- Australia and South America and other countries are higher than the USA in attacks
- ** in general attacks have increased in all countries over time.
- ** might be due to the fact that popularity of water activity has increased!
Australia Graph(N=412): x= years (1900-2009) y=number of attacks 0-140 - explain it! ( population, all attacks, fatalities)
- population has been increasing over time (linear)
- attacks have increased overtime
- fatalities have fluctuated over time but in general they have remained low/decreased
- big increase in number of attacks …especially surfing in seal zones
Florida Graph(N= 609): x= years (1900-2009) y= number of attacks (0-300) - explain it! (population, all attacks, fatalities)
- shark attacks remained extremely low until 1950-59 where they started to increase
- fatalities have remained extremely low
- population has been increasing!
- *more ppl in water than beach….
Hawaii (N=97) : x= years (1900-2009) y= number of attacks (0-40)
- explain it! (population, all attacks, fatalities)
- all attacks did not really begin to increase until 1950-59 and continued over time.
- population increased over time!
- fatalities increased in 1950-59 but stopped….
L> increased again in 1990-99 but decreased in 2000-2009.
** tiger sharks mostly….same low attacks
Attacks can be categories into two areas which are what?
- Provoked (Ex: grabbing their tail..holding on to it when it is trying to get away…trying to take a hook out)
- Unprovoked (basically no idea why the shark attacked…dominance?….may not be unprovoked in the sharks mind)
L> however, there may have been a reason, just unknown
Increase in shark attacks is based on ?
population growth
Explain what a provoked attack is?
- human initiates contact ( 53 incidents in 2013)
* *multiple causes
What are the three major types of unprovoked (natural environment without provocation) shark attacks?
- Hit and run
- Bump and bite
- Sneak
* * usually fatalities are due to hit and run or sneak attacks!
Hit and Run attacks:
- Occur where?
- Do people usually see the shark?
- Does the shark return after the attack?
- What are reasons for mistaken identity?
- in surf zone ( swimmers, surfers)
- seldom see the shark (visibility is usually an issue)
- shark does not return
- Mistaken Identity:
L> poor visibility
L> breaking surf
L> social behaviours by sharks ( dominance)
L>contrasting colours sharks can pick up
**big issue in Florida!
Bump and Bite/Sneak:
- whats the injury state?
- who tends to be of greater risk?
- bump and bite usually has sharks ___ and ___ prior to attack
- Sneak occurs without??
- What is extremely common with these types of attacks vs Hit and run?
- This could be a form of ___ or ___ behaviour.
- tend to involve bigger or smaller sharks?
- greater injury and most fatalities
- divers or swimmers in deeper water
- bump and bite usually has shark circling and bumping prior to attack
- sneak occurs without warning
- repeated attacks not uncommon
L> focuses on the initial individual but not the others that are around it or trying to help! Tunnel vision sort of! full feeding behaviour - feeding or antagonistic behaviour
**tend to involve bigger sharks
Positive identification of attacking sharks is very difficult or easy?
- very difficult since victims rarely make adequate observations of the attacker during the “heat” of the interaction.
** when being attacked the last thing on your mind is what is attacking you! It’s am I going to die…
L> after the fact people have a desire to know!
Tooth remains are seldom or frequently found in wounds?
- they are seldom found in wounds!
- and diagnostic characters for man requiem sharks ( family Carcharhinidae) are difficult to discern even by trained professionals.
- all seem fairly similar!
- small wounds = small spa or juvenile shark!
What are the big three sharks that are responsible for Bump and Bite/Sneak attacks?
- white, tiger shark and bull shark!
What are the rest of the sharks that are responsible for Bump and Bite/Sneak attacks?
- Great hammerhead
- shortfin mako
- oceanic whitetip
- caribbean reef
- galapagos
**fairly big sharks are veracious
** Caribbean reef shark you would have to provoke it or something must be wrong with it to attack…they circle and as it gets tiger it is closing in on you!
L> also if it is hooting at you fast= loo out
What are the main sharks involved in hit and run attacks?
L> attacks in florida?
- Blacktip
- Spinner
- Blacknose
- a lot of sharks get blamed for these like hammerheads…
- based on 20-30 attacks in florida each year
Hit and Run:
- A number of ___ sharks in the genus _____ likely are involved in many more attacks than they are credited in this list and, if the list could reflect that reality, ___ bites would push such species as the ___, ___ and ___ towards the bottom of the list.
- Requiem
- Carcharhinus
- Carcharhinus
- sandtiger
- hammerhead
- nurse shark
Rank countries in order of most attacks!
- Continental USA (1055)
- Australia (520)
- Africa (339)
- Asia and Hawaii (129)
- Pacifica Islands and Oceanic (126)
- South America (117)
- Antillas and Bahamas (70)
- Middle America (57)
- Europe and New Zealand (49)
- Reunion Island (33)
Where in the US are the most attacks?
Florida and Hawaii !
L> California and SA are next on the list
Graph: Victim's Activity During Unprovoked Shark Attacks Worldwide 1900-2009 (N= 1826) - y= number of attacks - x=decade L> Explain the graph! activity: Surface recreationists swimmers and bathers divers entering or existing water
- from 1900 to 1950-1959 swimmers and bathers were attacked in higher numbers BUT it continued to increase and was the second highest in attacks of the rest here.
- 1960-2009 = huge increase in surface recreationists activity getting attacked
- divers being attacked fluctuate from 1950-2009 but not in a high number at all
- entering or exiting the water and being attacked the numbers are extremely low (highest at 2000-2009)
Graph: Shark Attacks on Surface Recreationists Worldwide 1900-2009 (N=807)
- y= number of attacks
- decades
- attacks increased over time 2000-2009 = highest numbers: 318 attacks - 1990-1999: 217 - 1980-1989: 126 - 1970-1979: 46 - 1960-1969: 31 - 1950-1959: 8 - 1940-1949: 3 - 1930-1939: 0 - 1920-1929: 1 - 1910-1919: 3 - 1900-1909: 0 **indicates more people surfing etc...
Shark attacks on Divers Worldwide 1900-2009(N= 164)
- y= number of attacks
- x= decades
- *explain it
- fluctuated over time but in general it has increased!
- 2000-2009 = highest number of attacks (53)
Shark Attacks on swimmers and bathers worldwide 1900-2009 (N=795):
- y=number of attacks
- x= decade
- explain it
- general increase over time in attacks minus a decline that is seen in 1970-89 period
- 2000-2009 = highest attacks! 183
Shark Attacks on victim upon entering or exiting the water 1900-2009(N=60):
- y= number of attacks
- x= decade
explain??
- it fluctuates over time
- highest attacks = 11 in 2000-2009
L> general decline prior to this point
-1950-59 = second highest for attacks at 10
-L> general increase up to this period
Florida Shark Attacks:
- ___ total attacks
- ___ fatal, last fatality was in ___.
- What area has the highest risk of attack?
- 687
- 11
- 2011
- Volusia (257 attacks)
Florida Shark attack by months
L> what month had the most attacks?
- september (103)
- August (84)
- July (73)
- October (72)
- April (62)
- June (61)
-November (44)
-March (41) - February (14)
- December (11)
- January (5)
**highest number of attacks are during warmer months…
L> increased number of young sharks
Florida Shark attacks:
- Time of unprovoked shark attacks in florid 1926-2012 (N=493)
- y= number of attacks
- x= time of day
- Explain the graph!
- highest number of attacks are in the 11am-6pm range (greatest risk
Florida Shark Attacks:
- Victim activity during unprovoked shark attacks in florida by decade (N=590)
- y= number of attacks
- x= decade (1900-2009)
L> activities: surface recreationist, swimmers and waders, divers and entering or exiting water.
**explain graph
- sharks are attacking people more when they are participating in surface recreationist activity (highest in 2000-2009)
- Swimmers and waders= second highest at risk
- divers and people entering or existing water are least at risk!
- *two main ones increased over time …the others fluctuated at low numbers!
- entering or exiting water= highest risk level for it is right now 2000-2009…..highest risk for divers was in 1960-69
Florida Shark Attacks:
- Species involved with unprovoked shark attacks in florida (1920-2012) (N=97)
- Explain the pie chart!
Blacktip+bull shark>spinner shark> hammerhead> Nurse shark> Sand tiger> Sand bar shark+ lemon shark + tiger shark> blue shark> mako shark
California Attacks:
- __attacks, __ fatalities, last one in ___.
- ___ has the highest risk with _ attacks and _ fatalities.
- 110
- 10
- 2012
- San Diego
- 17
- 2
California:
- California Shark attacks by month 1926-2012 (N= 103)
- y= number of attacks
- x= month
- Rank months highest to lowest risk
- October = highest risk month
- september
- august
- july
- May + November
- December + June
- January + February
- March
California:
- Time of unprovoked shark attacks in California 1926-2012 (N=79)
- y= number of attacks
- x= time of day
- a lull in the peak seen in florida! (surfers)
- highest risk time= 10:00am- 10:59am and 4-4:49pm
- 12-12:59pm= second highest risk
- waves are usually big early morning….
California:
- Species involved with unprovoked shark attacks in California 1950-2012 (N=82)??
- White sharks = 97%
- Blue shark (1%)
- Leopard shark (1%)
- Mako(1%)
California:
- Victim activity during unprovoked shark attacks in California by decade 1920-2009 (N=94):
- y=number of attacks
- x= decade
- surface recreationist > swimmers and waders> divers> entering or exiting water
- risk rank!
- highest level of risk - surface recreationist in 2000-2009
- ** divers increased over time up to 1999
- ** swimmers and waders fluctuated over time ( highest in 1959
Great White Shark Attacks:
-how many known great white shark attacks?
- 7
L> not including attacks that they are not sure what the culprit is.
-** the number could be higher because they are unsure if the bites were done post-mortem or pre…was it the shark that killed them?
Great White Shark Attacks:
= The rise in attacks relates to?
- increased in grey seal population!
- the number could be higher because they are unsure if the bites were done post-mortem or pre…was it the shark that killed them?
White Shark Attacks:
- Unprovoked White Shark Attacks and percent fatal 1900-2009 (N= 248)
- y= number of attacks and percent fatal
- x= decade
- explain graph
- attacks increased over time… peaking at 65 in 2000-2009
- percent fatality has decreased over time quite dramatically
L> it rised from 1910-1929 and plateaued until 1939
White Shark Attacks:
- Age of white shark victims 1876-2012 (N=228)
- 43%= 20’s (surfers etc) highest risk
- 23%= 10’s highest risk
- 18%= 30’s highest risk
- 11%= 40’s
-4%= 50’s
1%= 60’s and 70’s
White Shark Attacks:
- Gender of White shark attack victims 1879-2012 (N= 270)
- 93%= male
- 7%= female
- *most surfers= males….
White Shark Attacks:
- Length of white sharks involved in unprovoked attacks 1580-2012(N=198)
- 48%= 10-14.9ft
- 24%= 5-9.9ft
- 23%= 15-19.9ft
- 4%= 20-24.9ft
- 1%= 0-4.9ft
- ** 10-14ft long= not very old sharks are involved in attack…middle of transition from feeding on fish to marine mammals (exploratory?)
White Shark Attacks:
-Race of white shark attack victims 1879-2012(N=207)
- 77%= caucasian (surfing culture/water sports)
- 18% = other/unknown
- 2% each for oriental and negroid
- 1%= polynesian
- *these are only reported attacks…what about unreported ones!
White Shark Attacks:
- Time of unprovoked white shark attacks 1916-2012 (N=200)
- x= time of day
- y= number of attacks
- explain
- early morning = increase until lunch
-why is there a dip around lunch?
L> population in water is higher in afternoon
***6-7pm = vision decreases because of visibility…risk of mistaken identity
** 2-4pm = highest attacks
White Shark Attacks:
- Water temperature during unprovoked white shark attacks 1922-2012 (N=63)
- highest attacks = 15-19.9 C
- 20-24.9 C
- 10-14.9 C
- 25-29.9C
- 5-9.9 C
- **based on human preference??? wait until water is warmer to go swimming….white sharks do not really like higher temperatures therefore attacks tend to happen in cooler water!
White Shark Attacks:
- Unprovoked white shake attack depths 1907-2012 (N= 240)
- highest risk = 0-5 ft –> basically they are following the wave in….BUT it is easier for people to get to shore…so this could be good for victims?
- the rest are extremely low!
- 6-10
- 11-20
- 31-40
- 21-30
Profile of Attacks on Divers:
- __ attacks
- ___ leads with __%, ___ with __%
- 218
- Australia
- 32%
- US
- 24%
- *underwater activity……recreation diving makes ups huge part of diving!
Profile of Attacks on Divers:
-Outcome of unprovoked shark attacks on divers 1802-2012
- 81%: non-fatal
- 19%: fatal
Profile of Attacks on Divers:
- Diving activity of unprovoked shark attack victims 1802-2012
- SCUBA diving: 41%
- Diving ( no details): 27%
- Free Diving: 25%
- Hookah diving: 3%
- Pearl diving: 2%
- Hard hat diving: 2%
- spearfishing 1%
Unprovoked shark attacks on divers and percent fatal 1900-2009 (N=197)
x= decade
y= number of attacks and percent fatal
-highest risk was in 1960s
- 2nd: 1990s
- 3rd: 2000s
-4th: 1980s
-5th:1970s
-6th: 1950s
- 7th: 1920s
-8th: 1900s
- 9th: 1940s
- 10th: 1910s
** fatalities spiked in 1920 (highest)
L> decreased until 1980…but then it spiked a bit (not as high as before) and then it decreased quite a bit
** could be due to better medical procedures
Gender of divers involved in unprovoked shark attacks prior to 1990 (N=124)
- males 99%
- females 1%
Gender of divers involved in unprovoked shark attacks 1990-2012 (N=80)
- 90% male
- 10% female
Attacks on divers: - Activities of others in the area of unprovoked attacks on divers 1820-2012 (N= 125 of at least one of the activities going on; individuals may be represented in more than one category) Attack numbers for these activities: L> Diving L> Normal bathing/swimming L> Wading L> Surfing L> Boating L> being unusually loud L> Thrashing or flailing
- 99
- 11
- 7
- 4
- 3
- 1
- 1
- 1
- *diving has the highest risk of attack vs anything else
Attacks on divers:
- Divers’ time in water prior to unprovoked shark attacks 1938-2012 (N=45)
- 40%: less than one hour
- 36%: within a couple of minutes
- 13%: within 15 mins
- 9%: over an hour
- 2%: immediately upon entry
- the way we swim is the same vibrations as an injured fish..gives off….dinner bell ring ring ring
Activities of divers struck less than an hour after entering water 1938-2012(N=42)
- SCUBA Diving
- Diving (no details)
- Free diving
- Hookah diving
- pearl diving
- spearfishing
- 57%
- 7%
- 26%
- 5%
- 3%
- 2%
Activities of divers struck more than an hour after entering water 1966-2012(N=4)??
- SCUBA diving
- Free diving
- 75%
- 25%
Time of unprovoked shark attacks on divers 1936-2012(N=109)
- y= number of attacks
- time (24 hour clock)
- most attacks occur in the morning
- then afternoon and evening are tied
- **morning group: highest risk …sharks vision decreases as the sun goes
Unprovoked shark attacks on divers by day of the week 1925-2012(N=153)
- most attacks are on sunday
- saturday
- Wednesday and Thursday
- Monday
- Tuesday
- Friday
Divers’ clothing during unprovoked shark attacks (N=37) ?
- Full wet suit: 68%
- Swim suit: 27%
- Shorty wetsuit : 5%
Special features of divers’ coshing during unprovoked shark attacks (N=47)
- non-reported 36%
- highly contrasting colours : 30%
- shiny patterns: 17%
- very bright colours : 13%
- other : 4%
Clothing pattern worn by divers during unprovoked shark attacks (N=45)
- no pattern : 80%
= striped: 11% - other pattern: 9%
Primary colours worn by divers during unprovoked shark attacks (N=67)
- 64%: black/grey/slate
- 16%: blue/aqua/turquoise
- 6%: white/silver/ talc
- 5%: red/pink/rose/magenta/coral/ maroon
- 3%: brown/tan/buff/rust/sienna/cocoa/beige
- 4%: green/olive/teal/lime/avocado
- 2%: yellow/gold/khaki/lemon
People near shark attacks on divers (N=139)
- y= number of attacks
- x: <10ft(none, one, more than one), 10-50ft (none, 1-5, 6-10, 11-15, 16-20 and several) and general area(yes or no)..
-none= highest number of attacks L> one: second highest L> more than one: third - 10-50ft: L> none: highest L> 1-5: 2nd L> 6-10, 16-20, several: tied for third L> 11-15: none - General area: L> Yes: highest number of attacks when people are in the general area L> no: second highest **what were people doing in the area around the divers?....do not swim alone!!! isolation= highest risk...shallow waters
Non-human presence in vicinity of shark attacks on divers (N=144, cases may be represented in more than one category)
L> y= number of attacks
L> x= item or animal (absent or present)
- boats are present the most
- pets are absent the most
- seals are absent the second most
- surfboards are absent the third most
- porpoise are absent the fourth most
- fish (half present and half absent?)
Possible attractants in vicinity of shark attacks on divers (N=205, cases may be represented in more than one category)
y= number of attacks
x= attractant
- wounded fish(3rd highest attacks when absent(highest when present))
- garbage (2nd highest attacks when absent)
- sewage (fourth highest when absent)
- victims blood(fifth highest when absent)
- other human blood (highest attacks when absent…)
Diversionary action taken by divers involved with shark attacks.
- struck(n=32)<–most effective
- *see graph honestly this is confusing
- does not explain the data well
Diversionary action taken by divers involved with shark attacks.
- hitting the shark is?
- the most effective at scaring off it but depends on species, intent or size.
Diversionary action taken by divers involved with shark attacks.
- kicking only works with?
- with smaller sharks
Diversionary action taken by divers involved with shark attacks.
-How do you tackle an it via aggression?
- hold your ground…a lot of the time the shark veers away.
Diversionary action taken by divers involved with shark attacks.
-Other??
- got out of the water……
- go to the bottom and stay there with your back to the reef! (ambush predator therefore can’t really effectively attack)
Age of divers involved in unprovoked shark attacks 1929-2012 (N=123)
x= age
y= number of victims
- highest= 25-29 and 30-34
- 35-39
- 20-24
- 15-19
- 40-44
- 45-49
- 10-14
- 55-59
- 60-64 and 55-59
Weight of divers involved in unprovoked shark attacks 1954-2012(N=24)
x= weight in pounds
-y= number of attacks
- 160-179pounds= highest attacks
- 140-159= second
- 100-119
- <100, 120-139, 180-199
- 200=219: none
- larger people tend not to be attacked? maybe not in the water a lot…
- *most divers weight about 140-179 pounds !
Height of divers involved in unprovoked shake attacks 1962-2012(N=25)??
x= height(inches)
y= number of attacks
- 70-74: highest number of attacks
- 65-69: second
- 50-64= tied for 1 attack each.
Divers Body parts injured during shark attacks (N= 224, individuals may be represented in more than one category!)
- Legs: 44%—> lower leg: 45%…thigh: 27%…feet= 24%…toe(s) = 4%
- Arm: 31%–> arm= 56%….hand: 22%…shoulder: 14%…finger(s): 8%)
- Torso: 23%—> abdomen: 27%, buttocks: 21%, chest: 20%; back: 14%; waist and genitals: 9% and 9%
- Head: 2%
See surface conditions during shark attacks on divers(N=71)
- calm: 80%(also includes surf! higher risk on good days bc more people are in the water)
- choppy: 11%
- swells: 9%
- higher vis increases attacks ….warm water temp: more attacks …bc more people in water but diving and surfing you are out in colder water.
Water visibility during shark attacks on drivers (n=46)
- y= percentage of attacks
- x= visibility (ft)
- highest number of attacks: 10-10 ft visibility
- 0-9= second
- 20-29= third
- *main ones the rest are relatively small
Water temperature during shark attacks on divers (N-520
- Y= Number of attacks
- X= water temp C
- highest number of attacks were at 21C (most in other regions,2nd= florida, third= Australia)
- second: 18C (most unprovoked….then Australia then florida)
- Third: 26C( main = other region, second: florida, third: Australia)
Water clarity during shark attacks on divers (N=87)
- murky: 33%
- clear: 67%
Number of close passes sharks made prior to attacks on divers (N= 67)
- multiple: 46%(giving you lots of warning)
=-single: 26%(assessing) - none: 28%(full blown attack and no warning)
Number of discrete bites sharks inflicted on divers during attack (N=132)
- other: 51%
- none: 31%
- several: 18%
Nature of sharks’ first strike during attacks on divers (N=136)
- violent: 73%
- no direct contact: 15%
- minimal turmoil : 11%
Direction from which sharks attack divers
- Below and front= 28% per each
- behind and side= 20% per each
- above: 4%
Sharks behaviour prior to attack on divers (N=115)
- 42%: shark not seen
- 15%: straight away approach to victim
- 13%: seen, but not well enough to evaluate behaviour
- 9%:circling victim
- 8%: swimming erratically
- 7%:swimming normally
- 5%: following victim closely
- 1%: in position between victim and beach , reef etc.
Shark behaviour after final strike on diver (N-109)
- 36%: left area
- 31%: not seen at all
- 5%: remained attached, forcibly removed from victim
- 4%:follow victim
- 2%: remained attached, not for removed from victim
Shark behaviour after initial strike on diver (N= 119)
- 65%: released initial hold but did not bite victim again.
- 20%: made multiple deliberate strikes
- 9%: released initial hold and quickly bit victim again
- 6%: frenzied behaviour
