SHARK CONSERVATION.ppt

7/27/2019 SHARK CONSERVATION.ppt

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The sharks, skates and rays belong to vertebrate

class Chondrichthyes; subclassElasmobranchiiThey differ from bony (teleost) fish as they have:

a cartilangenous skeleyon 5+ gill slits instead of a single boney gill covering (operculum)

They are an extremely old group of fish having evolvedapproximately 400 million years ago.

Their longevity on the planet is probably due to effectivebody plan and adaptation for various marine ecologicalniches (most, but not all, are high trophic level predators)

There are an estimated 400 extant species of sharks and 600

species of rays.

Sharks


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Biggest and Smallest

The largest predatory shark is the great white

23 long & 7,000 lbs

Basking sharks are filter feeders found in cooler

waters feeding on plankton - up to 33

The largest is the whale sharkanother planktonicfilter feeder

Over 40 long and 20,000 lbs+

But Carcharodon megalodonwas the largest

50 and 20 tons

The smallest shark is the spined pygmy shark

7 to 8 inches long


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Most sharks are predatory, but some are also scavengers andthe largest are plankton feederssimilar to baleen whales.

Their habits varies from shallow reefs and coastal areas to

the open ocean, to abyssal seabed.

Many are highly migratory

Some species are also freshwater tolerant and can be found

in estuaries, rivers, or even lakes.

Shark habitat


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Sharks have from 5 to 7gills slits on each side of

their bodies

Shark Biology 101


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Sharks have asymmetric caudal

(or tail) fins.

This helps to provide lift for

swimming.

Generally fast, predatory sharks have

the most symmetrical caudal fins

Shark Biology 101


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The pectoral fins provide liftin the same way

an airplanes wings do

The larger a shark is the larger it's pectoral fins

must be.

Typically sharks are heavier than seawater, somaintaining buoyancy is an issue for them

Shark Biology 101


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Unlike teleost fish, the skin of sharks is usually made up of

thousands ofplacoid scales ordenticles

- which have the same structure as teeth


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Shark Biology 101

Most vertebrate have teeth that are locked into

sockets in their jaws

The teeth of cartilaginous fish are simply attached to the jaw byfleshy tissue

This means that teeth are frequently torn off

Therefore teeth grow in multiple rows.

If a tooth is lost, a new tooth is pushed forwards to replace it


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Shark's eyes have a large number of rods cells which gives them

good low light vision.

In addition to this they have the tapetum luciduma layer of

protein crystals underneath the which lies beneath the retina,

reflects light back through the retina - increasing the light

received by rod cells

Shark Biology 101


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Although sharks are often portrayed as killing

machines with little intelligencethey actually have well developed brains

In fact, their brain weight to bodyweight ratios of

some sharks exceed those for most bony fish,

many birds, and some mammals

Shark Biology 101


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Sharks have the normal five sensestheir sense ofsmell/taste is extremely good

They also have two additional senses

Shark Senses

The lateral l ineis a canal containing sensory cells

this canal is connected to the surrounding water by pores

Via these pores sharks can detect vibrations in

the water

They could detect a single drop of blood in an

Olympic-sized swimming pool


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Shark Senses

In addition, located in their snouts theyhave Ampul lae of Lorenziniconnected by

pores to their surroundings

These organs can detect electrical impulses

i.e. the firing of nerve fibers

Theoretically they could detect the electric field

produced by a 12 volt battery being dropped into

the middle of the Atlantic Ocean


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Sharks and rays have developed reproductive strategies which

are very similar to those of large mammals with few naturalpredators (such as the whales or elephants).

i.e. k -selected They grow slowly,

They mature late (not until an age of 20-25 years for some species),

They have a relatively small number of young, and

They are long-lived (up to 70 years).

The few young that each female produces in her life-time are

born large after a long pregnancy, and have a high likelihood

of surviving to adulthood - under natural conditions.

Sharks can be oviparaous (egg-laying), oviviviparous

(lay eggs but they hatch within the mother) or viviparous (live young)

Shark reproduction


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The very characteristics which have made sharks and rays

such successful and important species are now threateningtheir survival.

They are adapted to a position at or near the top of the food chain

in the marine environment.

Each female only produces enough young to replace the population

under low, natural levels of mortality.

They cannot adapt by producing much larger numbers of young toreplace the huge quantities now being killed by man.

As a result, sharks and rays are now seriously threatened by

unregulated fisheries and other anthropogenic mortality.

Shark depletion


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In January 2003 Baum et al. published an analysis of logbookdata on shark bycatch taken by U.S. pelagic longline fleetstargeting swordfish and tunas in the western North Atlantic.

Six shark species or species groups were recorded from 1986onward and eight shark species from 1992 onward.

This allowed a calculation of incidental shark catches over aperiod up to 1.5 decades.

With the exception of mako sharks (genusIsurus), sharkpopulations of all recorded shark species in the western NorthAtlantic had declined by more than 50% in the past 8 to 15 years

Scalloped hammerhead sharks (Sphyrna lewini), great whitesharks (Carcharodon carcharias), and thresher sharks (genus

Alopias) have declined by more than 75% over the past 15years.

These results indicate the level of shark depletion in the oceans


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Baum, J. et al. 2003. Collapse and conservation of shark

populations in the Northwest Atlantic. Science 299: 389-392.


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FISHING

Targeted fisheries

- Commercial:

- Fins (shark fin soup)

- Meat- Cartilage (for medicines etc)

- Leather (sharkskin boots/bags etc)

- Oil (high in squalene)

- Teeth and jaws (curios and decorations)- Sport

By-catch

Also habitat loss and depletion of food sources

Causes of depletion


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Shark finning

Finned sharks Shark fin display, Sekupang, Indonesia


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By-catch

Fisheries by-caching sharks Long-lines targeting other fish (swordfish, tuna)

Trawls (shrimp, ground-fish)

Gill-nets, purse seinesoften catch more sharks than targetspecies

Trap entanglement

Also, beach meshes (used in S. Africa and Australia) catchmany sharks (and sea turtles, dolphins, dugongs), many onthe SHOREWARD side of the nets (!)


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Oversix mil li onblue sharks have been taken annually from

the world's oceans over the past few years, most as by-catch inhigh seas fisheries for other species of fish.

Overall, it has been estimated that some 100 mil l ionsharks

have been taken annually from the sea in recent years.

The numbers of rays taken in fisheries have not been

estimated. Many targeted fisheries for sharks and rays haveresulted in serious population declines.

Moreover

Basking shark and porbeagle fisheries in European waters have collapsed after just a few

years of intensive fishing.

The common skate, the largest ray found in European waters and once abundant in

fisheries, is now scarce. It has disappeared completely from some areas, including thesouthern North Sea and the Irish Sea.

Shark depletion


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Why should sharks be conserved?

They are a top predator and 'keystone' marine species. Removing sharksmay unbalance ecosystems

-i.e. if large sharks are removed, commercially-important fish populationsmay be out-competed by less valuable fish which were formerly eaten by the

sharks.

Properly managed, sustainable shark and ray fisheries could provide foodand income to fishing communities.

Sports angling is a major economic activitybut caught sharks do not haveto be killed. Several areas have successful catch and release sports angling schemes.

Tags attached to released animals also provide important scientific information.

These are some of the most interesting and spectacular of marine animals. Shark tourism is a growing activityeither boat based or in waters (scuba

diving). There are concerns from white shark watching companies that theirtarget species is decliningprompting conservation advocacy

Intrinsic value as highly specialized and biologically fascinating species


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Its hard to get people to look at sharks as something beyond

that of a resource to be exploited

- Theyre fish therefore, theyre hard to study, so not much isknown about them

- Have a nasty tendency to occasionally eat people

- Dont really evoke a nurturing response from people, unlike the

following predator

The challenge


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Versus


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Shark attacks


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Shark Attacks

Actually relatively rareonly 50-75 a year

globally and very few are fatal

More people are killed each year by BEES, PIGS

or COCONUTS than sharks

More people are killed each year by dogs than are

killed in 100 years by sharks

The majority of shark attacks are by

Tiger sharks (35%)

Great white sharks (26%) or

Bull sharks (17%)


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Shark Protection Laws Protection of white sharks and the outlawing of trade in their body-products

In South Africa since 1991.

Similar prohibitions were passed in California (State Assembly Bill AB 522) andFlorida (US) and the Australian states of Tasmania, South Australia, New SouthWales and Western Australia.

Magnuson-Stevens Fishery Conservation and Management Act (U.S.)

2000US Shark Finning Prohibition Act

HR 5461 (June 6.)prohibiting finning within 200nm of US coast

Convention on the International trade in Endangered Species Great white shark added to Appendix II on 12 October 2004

2004 - a resolution urging an international ban on shark finning was passedby the United Nations General Assembly at its fall meeting.

On Nov. 17, the General Assembly complied by "urging" member nations toban "directed shark f isheries conducted solely for the purpose ofharvesting shark f ins . . . and to encourage the ful l use of dead sharks."

2004 - on Nov. 23, 63 member nations of the International Commission for

the Conservation of Atlantic Tunas (ICCAT)agreed toban shark finning in the Atlantic Ocean and Mediterranean


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In August 2002, the U.S.

Coast Guard boarded theKing Diamond II, a

suspicious U.S. vessel

riding low in the water off

the coast of Acapulco,Mexico.

On board were 32 tons of

disembodied shark fins.

The fins were estimated to

represent the taking of

some 30,000 sharks.

The King Diamond Case


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The boat was charged under the 2000 Shark Finning

Prohibition Act.

In May 2003, NOAA levied a fine totaling $620,000 on the

King Diamond II

The defendants argued that they were not a fishing vesselthey were merely transporting goods caught by other vessels,

i.e. a container ship and were exempt from the law/

But on 21th January 2005, Judge Barry Moskowitz ruled that

any US flagged ship receiving shark fins, although they maynot have gear on board, was a fishing vessel.

The King Diamond Case

Sh k C ti Th W F d


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Introduce of effective management on a regional basis to

regulate shark and ray fisheries and ensure their

sustainability.

Reduce shark and ray bycatch and mortality in other

fisheries.

Improve records of catches, landings and international trade

in species of sharks and rays.

Increase research effort on the biology of sharks and rays

and impacts of fisheries.

Improve management of critical habitats, including nursery

grounds, under threat.

Educate the public and decision-makers abut the issue

Shark ConservationThe Way Forward


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Anti-finning poster, from http://www.elasmo.org/broth.htm

Education


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Thanks to Heather McDuff

and
http://www.sharktrust.org/cgi/home.asp

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