Shark Conservation 2253k

Sharks The sharks, skates and rays belong to vertebrate class Chondrichthyes; subclass Elasmobranchii They differ from bony (teleost) fish as they have:

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

They are an extremely old group of fish having evolved approximately 400 million years ago. Their longevity on the planet is probably due to effective body plan and adaptation for various marine ecological niches (most, but not all, are high trophic level predators) There are an estimated 400 extant species of sharks and 600 species of rays.

Biggest and Smallest The smallest shark is the spined pygmy shark – 7 to 8 inches long 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 shark – another planktonic filter feeder Over 40’ long and 20,000 lbs+ But Carcharodon megalodon was the largest – 50’ and 20 tons

Shark habitat • Most sharks are predatory, but some are also scavengers and the largest are plankton feeders –similar 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 Biology 101

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

Shark Biology 101

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

The pectoral fins provide lift – in the same way an airplane’s wings do The larger a shark is the larger it's pectoral fins must be. Typically sharks are heavier than seawater, so maintaining buoyancy is an issue for them

Shark Biology 101

Male sharks have two ―claspers‖ – specialized fins which are inserted into the reproductive duct of the female – internal fertilization

Unlike teleost fish, the skin of sharks is usually made up of thousands of placoid scales or denticles - which have the same structure as teeth

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 by fleshy 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

Shark Biology 101

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 lucidum – a 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

Although sharks are often portrayed as killing machines with little intelligence – they 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 Senses • Sharks have the normal five senses – their sense of smell/taste is extremely good •They could detect a single drop of blood in an Olympic-sized swimming pool

• They also have two additional senses • The lateral line is 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

Shark Senses •In addition, located in their snouts they have Ampullae of Lorenzini connected 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

Shark reproduction • Sharks and rays have developed reproductive strategies which are very similar to those of large mammals with few natural predators (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 depletion The very characteristics which have made sharks and rays such successful and important species are now threatening their 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 to replace 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.

• In January 2003 Baum et al. published an analysis of logbook data on shark bycatch taken by U.S. pelagic longline fleets targeting swordfish and tunas in the western North Atlantic. • Six shark species or species groups were recorded from 1986 onward and eight shark species from 1992 onward.

• This allowed a calculation of incidental shark catches over a period up to 1.5 decades. • With the exception of mako sharks (genus Isurus), shark populations of all recorded shark species in the western North Atlantic had declined by more than 50% in the past 8 to 15 years • Scalloped hammerhead sharks (Sphyrna lewini), great white sharks (Carcharodon carcharias), and thresher sharks (genus Alopias) have declined by more than 75% over the past 15 years. • These results indicate the level of shark depletion in the oceans

Baum, J. et al. 2003. Collapse and conservation of shark populations in the Northwest Atlantic. Science 299: 389-392.

Causes of depletion 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

Shark finning

Finned sharks

Shark fin display, Sekupang, Indonesia

By-catch Fisheries by-caching sharks • Long-lines targeting other fish (swordfish, tuna) • Trawls (shrimp, ground-fish) • Gill-nets, purse seines – often catch more sharks than target species • Trap entanglement Also, beach meshes (used in S. Africa and Australia) catch many sharks (and sea turtles, dolphins, dugongs…), many on the SHOREWARD side of the nets (!)

Shark depletion • Over six million blue sharks have been taken annually from the world's oceans over the past few years, most as by-catch in high seas fisheries for other species of fish. • Overall, it has been estimated that some 100 million sharks 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 have resulted 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 the southern North Sea and the Irish Sea.

Why should sharks be conserved? • They are a top predator and 'keystone' marine species. Removing sharks may unbalance ecosystems -i.e. if large sharks are removed, commercially-important fish populations may be out-competed by less valuable fish which were formerly eaten by the sharks. • Properly managed, sustainable shark and ray fisheries could provide food and income to fishing communities. • Sports angling is a major economic activity – but caught sharks do not have to 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 activity – either boat based or in waters (scuba diving). There are concerns from white shark watching companies that their target species is declining – prompting conservation advocacy • Intrinsic value as highly specialized and biologically fascinating species

The challenge…

• It’s hard to get people to look at sharks as something beyond that of a resource to be exploited - They’re fish – therefore, they’re hard to study, so not much is known about them - Have a nasty tendency to occasionally eat people - Don’t really evoke a nurturing response from people, unlike the following predator…

Versus

Shark attacks

Shark Attacks Actually relatively rare – only 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%)

Shark Protection Laws • Protection of white sharks and the outlawing of trade in their body-products In South Africa since 1991. Similar prohibitions were ed in California (State Assembly Bill AB 522) and Florida (US) and the Australian states of Tasmania, South Australia, New South Wales and Western Australia.

• Magnuson-Stevens Fishery Conservation and Management Act (U.S.) • 2000 – US 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 ed by the United Nations General Assembly at its fall meeting. On Nov. 17, the General Assembly complied by "urging" member nations to ban "directed shark fisheries conducted solely for the purpose of harvesting shark fins . . . and to encourage the full use of dead sharks." • 2004 - on Nov. 23, 63 member nations of the International Commission for the Conservation of Atlantic Tunas (ICCAT)—agreed to ban shark finning in the Atlantic Ocean and Mediterranean

The King Diamond Case • In August 2002, the U.S. Coast Guard boarded the King 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 • 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 vessel – they 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 may not have gear on board, was a fishing vessel.

Shark Conservation – The Way Forward • 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

Education

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

Thanks to Heather McDuff and