Available at http://planet.uwc.ac.za/nisl/Eco_people/Presentations/

Threats to biological diversity2: Over exploitation

Sam HopkinsBiodiversity and Conservation

Biology

Overexploitation is the use, by humans, of a natural resource to an extent that it is not sustainable

What is Overexploitation?What is Overexploitation?

A number of factors contribute to overexploitation

Possibly the rich countries over consuming

Lack of incentives to conserve such as environmental taxes

Economic growth causes environmental degradation however lowering economic growth in the rich countries will in turn lower it in the poor countries

Increases in the human population number

What causes overexploitation? What causes overexploitation? 11

Was a member of the Bovidae family

Ranged from Britain to Africa

By the 13th century it was only seen in Poland, Lithuania and Prussia

By 1564 only 38 animals remained

Ban imposed over hunting

Hunted to extinction by 1627

Examples of overexploitation:Examples of overexploitation:The AurochsThe Aurochs 2 2

The ship the St Peter became shipwrecked off Kamchutka in November 1741

They managed to survive by hunting the Sea Cow

The sea cow was estimated to be 28 feet long and 7-8 tons

When the shipwrecked men got off the island in Aug 1742 they told everyone about the sea cow when they got back

It had been hunted to extinction by 1768

Examples of overexploitation:Examples of overexploitation:The Sea Cow The Sea Cow 33

The Great Auk was a flightless sea bird

It was found in Canada, Greenland, Iceland, Norway, Ireland and Great Britain

As the animal had few natural predators it had no fear of humans which made them easier to hunt

Great Auk was hunted for food and feathers used for stuffing mattresses

The last pair were killed while sitting on an egg and for good measure the egg was smashed

Examples of overexploitation:Examples of overexploitation:The Great Auk The Great Auk 44

The passenger pigeon was a flocking bird found in North America

Estimates suggest that there were at least 3 billion individuals

The birds roosted together which made them an easy target

The hunter came up with several ingenious ways of killing the birds; suffocation by burning grass, fed alcohol soaked grain, beaten down with long sticks, netted and trapped using a decoy

The last one was seen in 1900 in Ohio

Examples of overexploitation:Examples of overexploitation:The Passenger Pigeon The Passenger Pigeon 55

The whole of the fur trade is an example of overexploitation

In the past when one animal has become rare the trade has just looked for another source to keep people in fashion

At the height of the squirrel trade half a million skins were exported each year

As land stocks of squirrels and minks became depleted the sea was looked to

This lead to the demise of the sea otter and by 1911 there were only 1- 2000 left

Examples of overexploitation:Examples of overexploitation:The fur tradeThe fur trade

One of the most well known examples of over exploitation is by the fishing industry

Commercial fishing fleets exceed the ecological limit

This has been caused by greed, a lack of data on actual fish stocks and better fishing equipment6

Out of the known 21,000 fish species only 9,000 are actually used by humans7

22 species are harvested in excess of 100,000 tonnes per year7

In the great lakes in North America there has been a decline in fish numbers and the lake trout and Atlantic Salmon are extinct in Lake Ontario8

The fishing industryThe fishing industry

The numbers of fish taken every year has declined recently but on average

500,000 tons of fish are taken from the Mekong river in S.E. Asia

210,000 tons of fish are taken from the Zaire river in Africa

210,000 tons of fish are taken from the Amazon river in S. America

Now fishermen are fishing down the food chain, as they cannot get the top predatory fish anymore they go for pelagic fish

The fishing industry The fishing industry 88

The exploitation of Reptiles and Amphibians can be traced back to the Romans

In a book called Natural History Pliny wrote

“Romans carried stones from a crocodiles belly as charms against aching joints, bound crocodile teeth to their arms as an aphrodisiac, treated whooping cough in their children with doses of crocodile meet, and trustfully administered burned crocodile skin mixed with vinegar as an aesthetic to patients about to undergo surgery. Woman used crocodile dung in a lint tampon as a contraceptive”

The Amphibian and Reptile Industry The Amphibian and Reptile Industry 99

It wasn’t just the Romans however, the Ancient people of America used toad secretions as a hallucinogen during religious ceremonies

Amphibians and reptiles have long been used as a source of protein

Now they are served as a delicacy or oddity for example, frogs legs au gratin, frogs legs teriyaki

The Amphibian and Reptile Industry: The Amphibian and Reptile Industry: Food Food 99

The commonly eaten frogs are Rana catesbeiana, Rana esculenta, Rana tigrina and Pyxicephalus adspersus

The commonly eaten reptiles are Green and Spiny Iguanas, Turtles, Crocodiles and Alligators

The Amphibian and Reptile Industry: The Amphibian and Reptile Industry: Food Food 99

Some facts and figures for you

The USA imported 2.5 million kilograms of frogs legs from Japan and India in 1976

Between 1979 and 1987 45,000kgs of alligator were sold every year

In the 1960s 150,000 Iguanas were eaten per year in Nicaragua alone

12 million fresh water turtles are sold to china from S.E. Asia per year

The Amphibian and Reptile Industry: The Amphibian and Reptile Industry: Food Food 99

Reptiles and Amphibians are also used for their skins

Reptiles skins make

Shoes

Purses

Belts

Amphibian skins make

Shoes

Purses

Belts

Book binding

Glue

Fishing lures

The Amphibian and Reptile Industry: Skins The Amphibian and Reptile Industry: Skins 99

Some facts and figures for you In 1981 alone 304,189 pairs of shoes were made from

Boa constrictors and 176,204 from Python reticularis Between 1980 and 1985 over 1 million Caiman crocodile

skins were sold every year 12 million Tegu skins were imported between the years

of 1980-1985 1-2 million Monitor skins are

exported from Africa and Asia each year

In 1986, 10.5 million reptile skins were sold legally in the USA

The Amphibian and Reptile Industry: The Amphibian and Reptile Industry: Skins Skins 99

One of the saddest trades is in cheap souvenirs Around the world amphibians and

reptiles are killed to make Crocodile teeth necklaces Crocodile feet key rings Rattlesnake rattle key rings Rattlesnake head/fang mementoes Stuffed and varnished toads in

amusing positions! At least 115,000 horned lizards are

thought to have been stuffed over the last 45 years

The Amphibian and Reptile Industry: The Amphibian and Reptile Industry: Cheap Souvenirs Cheap Souvenirs 99

The use of amphibians and reptiles for medicinal purposes has gone on for centuries as the excerpt from the book ‘Natural History’ showed

Iranians use a broth made from snakes and tortoises to fight disease

Asians use fat from monitor lizards for bacterial infection

People in Pakistan use oil from monitor lizards as an aphrodisiac

In Madagascar the fat and oil from a crocodile will treat burns, ulcers and cancer

In the Dominican Republic and Haiti the fat from a crocodile cures asthma

An alkaloid from the Epipedobates frog is a pain killer more powerful than morphine

The Amphibian and Reptile Industry: The Amphibian and Reptile Industry: Medicine (Traditional and Modern) Medicine (Traditional and Modern) 99

The exotic pet trade is growing rapidly

In 1990 the Florida Game and Freshwater fish commission noted the number of legal removals from the wild in Florida alone

In total 119,831 animals removed

49,240 snakes

41,493 frogs

1,050 salamanders

This is an under estimate as it only shows the traders that declared what they were taking

Between 1992 and 1994 74,000 Gulf Coast box turtles were taken from the wild

The Amphibian and Reptile Industry: The Amphibian and Reptile Industry: Pet Trade Pet Trade 99

Northern Red Salamader

Amphibians and reptiles are taken from the wild as teaching aids in schools and universities

Used in dissections in schools and universities

In the 1970s it was estimated that 15 million leopard frogs were taken from the wild for dissection teaching

Now people are more aware and more specimens are grown in captivity for use in research and teaching

The Amphibian and Reptile Industry: The Amphibian and Reptile Industry: Science, Research and Teaching Science, Research and Teaching 99

As you can see from the enormous figures I have given you over the past few slides this industry is not sustainable

Many of these animals have very long lives and are slow to reach maturity and reproductive rates are low

Over exploitation is not their only problem, add to the fact habitat degradation, invasive species, peoples persecution etc. and there will be a problem

The Amphibian and Reptile Industry:The Amphibian and Reptile Industry:The problems The problems 99

This is not just a western problem, overexploitation is occurring in Africa too

In the 1970s in West Africa a form of Semi nomadic farming was practised

This was suitable for the habitat

Stocking rate was close to carrying capacity

After 15 years of drought this system was not working anymore and instead of giving money to the farmers to carry on, the government gave money for well digging and animal health care

The human population in the area has grown by 2-2.5% and to keep enough animals to feed everyone the system is being overexploited

Farmers are turning to sedentary farming either settling with their few remaining livestock or growing crops or they move to an urban area

Overexploitation in Africa Overexploitation in Africa 1010

1. Fielder and Kaeiva (1998) Conservation Biology for the coming decade. Pp 396.

2. Wikipedia contributors. Aurochs [Internet]. Wikipedia, The Free Encyclopedia; 2006 Jul 9, 09:50 UTC [cited 2006 Jul 16]. Available from: http://en.wikipedia.org/w/index.php?title=Aurochs&oldid=62859780.

3. Explorenorth.com/library/yafeatures/bl.seacow

4. Wikipedia contributors. Great Auk [Internet]. Wikipedia, The Free Encyclopedia; 2006 Jul 11, 19:37 UTC [cited 2006 Jul 16]. Available from: http://en.wikipedia.org/w/index.php?title=Great_Auk&oldid=63278895.

5. http://www.si.edu/resource/faq/nmnh/passpig.htm

6. www.epa.gov/bioiweb1/aquatic/overexpl.html

7. Fielder and Jain (1992) Conservation- the theory and practice of nature conservation, preservation and management. Pp 157

8. Cox, G.W. (1997) Conservation Biology concepts and applications. Pp 158.

9. Pough et al. (2001) Herpetology 2nd Ed. Pp 500

10. Breman, H. (1992) Desertification control, the West African case; prevention is better than cure. Biotropica 24: 328-334

ReferencesReferences