Fish Behavior

Schooling Large association of individuals accomplished through olfaction (sense of smell), sound, vision & lateral line

Video Lateral line

Video - Fish bait ball in open waterFish bait ball in open water

Who Schools? Full-time schoolers (herring, sardines, mackerels)

Thousands of sharks visit a sea mount - Blue Planet: A Natural History of the Oceans - BBC - YouTube Part-time schoolers (hammerhead sharks, rays )..\..\..\My Videos\Windows Movie Maker 2 Sample File.WMV..\..\..\My Videos\Windows Movie Maker 2 Sample File.WMV

Why School? protection from predators Increase swimming efficiency Hunting efficiency To ensure reproductive success

Territoriality Most common in crowded environments that include areas that can provide shelter (kelp, coral reefs, salt marshes) Fighting Fish

Aggressive behaviors include raised fins, sound production, open mouth, rapid darting Ex. Angelfishes, Damselfishes Fighting Fish

Garibaldi Fish Emperor Angelfish

Migration Anadromous fishes: spend most time at sea but migrate to fresh water to breed (salmon, sturgeon) =j5pTnejk4s4https:// =j5pTnejk4s4

Most valuable of all harvested fish!

Catadromous fishes: breed at sea and migrate to rivers to grow and mature (freshwater eels) =BR1enXROmgAhttps:// =BR1enXROmgA

Navigation: land features, currents, salinity, temp, orientation to earth’s magnetic field

Breeding

Reproduction All are Sexual Some are simultaneous hermaphrodites (hamlets)

Some are sequential hermaphrodites (undergo sex reversal ex. Some basses, groupers, parrotfishes)

Fertilization Internal: most cartilaginous fishes and some bony (ex. Seahorses)

External/Spawning: the release of millions of eggs and milt (sperm) influenced by day length temperature & availability of food

Modes of Reproduction Oviparity-- Lay undeveloped eggs, embryo lives off the yolk sac until developed (90% of bony fish)

Pregnant rockfish

Ovoviviparity- The embryo also lives completely off the yolk, but the fully developed pup is born free of egg, fully formed(sharks, surf perches, some rockfish)

Shark Birth

Fish Sleep Different from birds, mammals, reptiles (no profound change in brain-wave pattern)

Ex. reef-dwelling parrotfish sleep at night – (occupies a crevice and envelopes itself in an odor-squelching slimy cocoon. Prowling predators can’t detect it)

Ex. Reef Whitetip, Tiger, and Great White Sharks "sleep" during the day and hunt at night The Central Pattern Generator that coordinates swimming movements isn’t in the shark’s brain but rather in its spinal chord (so these fish can swim while unconscious)

SHARK ATTACKS! Girl Attacked By Shark! Shark Expert Attacked Shark Attack! – YouTube Why Sharks Matter

Shark Attacks! The usual suspects… Bull Shark Tiger Shark Oceanic White tip Blue Shark Great White

Shark Attack Theories Sharks are hungry! attracted to human blood/urine will eat anything are starving due to overfishing, which has driven them near the coast However… Large sharks have the ability to remove large pieces of flesh/limbs, but majority of wounds are single bite or slash wounds.

Sharks are confused Many attacks occur in turbid water conditions Many bites are considered “investigative” Sharks are attracted to sound and brightly contrasted patterns and colors Sharks are mistaking people for other prey items However Some sharks have been found with whole people in their stomachs!

Sharks are aggressive Many sharks will exhibit an anti-predatory posture and aggressive slashing toward other sharks and people Some sharks are territorial (grey reef sharks) Great White sharks bite each other during social interactions Sharks may view people as competitors

How to reduce risk Always stay in groups since sharks are more likely to attack a solitary individual. Do not wander too far from shore --- this isolates an individual and additionally places one far away from assistance. Avoid being in the water during darkness or twilight hours when sharks are most active Do not enter the water if bleeding from an open wound or if menstruating --- a shark's olfactory ability is acute. Wearing shiny jewelry is discouraged

Avoid waters with known effluents or sewage and those being used by sport or commercial fisherman, especially if there are signs of bait fishes or feeding activity. Diving seabirds are good indicators of such action. Use extra caution when waters are murky and avoid uneven tanning and bright colored clothing - -- sharks see contrast particularly well. Refrain from excess splashing and do not allow pets in the water because of their erratic movements. Exercise caution when occupying the area between sandbars or near steep dropoffs --- these are favorite hangouts for sharks.

These data list the various diving activities divers were participating in at the time of attack. As the data depict, snorkelers are attacked the most frequently of any divers. This is most likely due to the fact that more people snorkel than SCUBA dive worldwide. (Updated July 2, 2009)

Most would expect that shiny features on clothing or gear would attract sharks, and so one would have a higher probability of being attacked by a shark if one swam with shiny features on the clothing or gear. This graph seems to contradict that hypothesis. The highest percentage of victims had no special features on their clothing, while the next highest percentage of victims had highly contrasting colors on their outfits or gear. It is possible that more of the population wears highly contrasting colors on their outfits and gear, or dive with no special features while less of the population swim with shiny features on their clothing and gear. It is possible that this is the cause of higher percentages of attacks on those divers. (Updated July 7, 2009, artificial lighting charts (above) updated May 18, 2009)

As the above data indicate, the majority of attacking sharks will strike a diver only once. A shark may only have one chance to bite the diver. Once a diver realizes he is bitten, he will do anything possible to escape from the shark, and fortunately, the majority of divers do escape from the shark. This is because an attack is classified as a shark aggressing towards a diver, not necessarily wounding the diver. (Updated June 29, 2009)

The above data indicate the behavior of the shark during the initial attack on the diver. A large percentage of the attacks were by sharks that attacked suddenly and violently. This is the most efficient strategy a shark uses when hunting prey. Shark attacks usually occur because a shark has mistaken a human for prey. The sharks that attacked more passively might have been "testing" the human to see whether or not the human is prey. (Updated June 29, 2009)

Map of World's Confirmed Unprovoked Shark Attacks (N=2,251)

World's Confirmed Unprovoked Attacks by White Sharks (N=244)

Map of United States (incl. Hawaii) Confirmed Unprovoked Shark Attacks (N=1032) Red=400 and above Orange= Blue=10-75 Green=1-9

SHARK JAWS

Dusky Shark

Lemon Shark

Blue Shark Jaws

Tawny Nurse Shark