Chondrichthyes & Human Hunters. Human Hunters a. The natural enemies of sharks include other...

Chondrichthyes & Chondrichthyes & Human HuntersHuman Hunters

Human HuntersHuman Hunters

a. a. The natural enemies of sharks include The natural enemies of sharks include other sharks, killer whales and the most other sharks, killer whales and the most dangerous to sharks, by far, are humansdangerous to sharks, by far, are humans

b. Gill nets kill sharks and mammals when b. Gill nets kill sharks and mammals when the intended catch is actually fish. Sharks the intended catch is actually fish. Sharks can drown if they do not have water can drown if they do not have water running over their gills.running over their gills.

Gill NetGill Net

Gill NetGill Net Thresher Shark caught in gill netThresher Shark caught in gill net

Gill NetGill Net

Lemon SharkLemon SharkCaught in Gill NetCaught in Gill Net

Gill NetGill Net

Life history strategy of sharksLife history strategy of sharks

Because sharks are slow breeders their Because sharks are slow breeders their populations are very vulnerable to an populations are very vulnerable to an increase in adult mortality and/or a increase in adult mortality and/or a reduction in survival of offspring.reduction in survival of offspring.

In recent years fishing has drastically In recent years fishing has drastically increased adult mortality and caused increased adult mortality and caused many shark populations to decline sharply.many shark populations to decline sharply.

Fishing and sharksFishing and sharks Historical records by early explorers, merchants and

others often mention the number and large size of the sharks that trailed their ships.

Sharks were competitors for the schools of herring, mackerel, capelin and other commercial that humans hunted, but sharks themselves were not fished for.

In the early 20th century the seas of the world still teemed with sharks, but that has changed dramatically.

Fishing and sharksFishing and sharks In the 1950In the 1950’’s long-line fisheries for tuna, s long-line fisheries for tuna,

swordfish, marlin and other prized species swordfish, marlin and other prized species treated sharks as a nuisance by-catch and treated sharks as a nuisance by-catch and many were cut free.many were cut free.

Today the growing wealth of Asian countries, Today the growing wealth of Asian countries, where shark fins are a delicacy, has made where shark fins are a delicacy, has made them a valuable catch.them a valuable catch.

Imports have tripled since 1980Imports have tripled since 1980 Hong Kong & China are the worldHong Kong & China are the world’’s largest s largest

importersimporters

Fishing and sharksFishing and sharks Shark Fin Soup: Upwards of $100/bowlShark Fin Soup: Upwards of $100/bowl Traditionally served at celebrationsTraditionally served at celebrations

Fishing and sharksFishing and sharks ““Boosts sexual potency,Boosts sexual potency,”” ““enhances skin enhances skin

quality,quality,”” ““increases oneincreases one’’s qis qi””

Fishing and sharksFishing and sharks

Connected to many Chinese medicinesConnected to many Chinese medicines

Shark Fins

Market in Singapore

Dried sharkfin can cost more than $500 a kilo Dried sharkfin can cost more than $500 a kilo and sharkfin soup up to $100 a bowl.and sharkfin soup up to $100 a bowl.

Longliners can set lines as much as 80 miles Longliners can set lines as much as 80 miles long that contain 30,000 baited hooks.long that contain 30,000 baited hooks.

In 1997 Hawaiian longliners caught more than In 1997 Hawaiian longliners caught more than 100,000 sharks and tossed almost 99% of the 100,000 sharks and tossed almost 99% of the body mass back. Why? They just kept the fins.body mass back. Why? They just kept the fins.

http://mythix.com/images/projects/ Shark_Finning_-_dead_shark_in_ocean.jpg

http://www.scubadiving.com/upload/images/Travel/20070326_sharkfinning_head.jpg

As worldwide fish stocks have declined, As worldwide fish stocks have declined, and often collapsed, less desirable and often collapsed, less desirable species including sharks have been species including sharks have been targeted by commercial fishing fleets.targeted by commercial fishing fleets.

As cod stocks collapsed, species such as As cod stocks collapsed, species such as spiny dogfish (marketed as spiny dogfish (marketed as ““rock codrock cod””) ) began to be served as a replacement in began to be served as a replacement in fish and chips.fish and chips.

Some species populations have been Some species populations have been devastated. devastated.

Once the oceanic whitetip was probably Once the oceanic whitetip was probably the commonest large animal in the world. the commonest large animal in the world. Today itToday it’’s numbers have declined 150-fold s numbers have declined 150-fold in the Gulf of Mexico and probably by the in the Gulf of Mexico and probably by the same amount elsewhere.same amount elsewhere.

Oceanic whitetip (Red Sea)

Along with declines in numbers another Along with declines in numbers another pattern common to other fisheries has pattern common to other fisheries has emerged, the sizes of the animals caught emerged, the sizes of the animals caught has fallen.has fallen.

Between the 1950Between the 1950’’s and 1990s and 1990’’s the size of s the size of individuals caught fell in a variety of individuals caught fell in a variety of species. species.

Percentage decline in size of individuals Percentage decline in size of individuals caughtcaught Oceanic whitetips (-33%)Oceanic whitetips (-33%) Mako (-50%)Mako (-50%) Blue (-50%)Blue (-50%) Dusky (-60%)Dusky (-60%) Silky (-83%)Silky (-83%)

This decline is because fishing often This decline is because fishing often preferentially removes older animals, and preferentially removes older animals, and even if it doesneven if it doesn’’t, fishing pressure is so t, fishing pressure is so intense that animals don’t live long enough intense that animals don’t live long enough to grow large.to grow large.

The simple truth is that shark populations The simple truth is that shark populations cannot be intensively harvested cannot be intensively harvested sustainably.sustainably.

They are long-lived, slow maturing and They are long-lived, slow maturing and slow reproducing.slow reproducing.

Summary

Current Failures:Current Failures:3rd: 72.76% Average3rd: 72.76% Average 55thth: 84.13% Average: 84.13% Average

100023540 (38, F, P)100023540 (38, F, P) 100023396 (46, F)100023396 (46, F)

100022936 (41, F, P)100022936 (41, F, P) 100038352 (59, F)100038352 (59, F)

100034273 (43, F, P)100034273 (43, F, P)

100023033 (45, F, P)100023033 (45, F, P) 66thth: 83.85% Average: 83.85% Average

100029402 (46, F, P)100029402 (46, F, P)

100038001 (48, P)100038001 (48, P)

100023385 (59, F)100023385 (59, F)

Exam on TuesdayExam on Tuesday

100022605 (52, P)100022605 (52, P) Summative Aquarium Data due FridaySummative Aquarium Data due Friday100038619 (54, P)100038619 (54, P)

100023823 (55, F)100023823 (55, F)

44thth: 83.24% Average: 83.24% Average

100034140 (19, F, P), 100034140 (19, F, P),

100022767 (48, P)100022767 (48, P)

100042337 (63, P)100042337 (63, P)

F = Failed ExamP = Missing Project

Today: 02/19/2014Today: 02/19/20141) Water changes/tank maintenance.

If you have a canister filter you need to clean that out today.

If your tank has a blue star drawn on it you MUST turn in a copy of your tank chemistry

2) Once you have finished, continue to work on your lab. The chondrichthyes specimens will not be out today, so I recommend that you work on “Station #5”

3) Once everyone has finished with their tanks we will take a quiz

4) If you need a few bonus points, come talk to me. I have a couple of tanks that need some extra care.

5) 3rd Period – We will have an observer tomorrow

Lab Groups:Lab Groups:

1) No more than 3 per group

2) You must move through the stations as a group.

3) I will be monitoring who is helping & who is not.

4) DO NOT touch any of the specimen unless you are wearing gloves.

m.Socrative.com Completion quiz grade

Room: 266770

Lab Charts:Lab Charts:

1. Ganges shark (Freshwater species)2. Borneo shark 3. Basking shark - North Pacific & Northeast Atlantic sub-populations 4. Speartooth shark 5. Whitefin Topeshark 6. Angular Angel shark - Brazilian sub-population 7. Smoothback Angel shark 8. Spinner shark - Northwest Atlantic sub-population 9. Pondicherry shark 10. Smoothtooth Blacktip

Top 20 Most Endangered Species of Sharks

11. Blacktip shark - Northwest Atlantic sub-population 12. Dusky shark - Northwest Atlantic & Gulf of Mexico sub-populations 13. Grey Nurse shark (aka Sand Tiger) 14. Great White shark 15. Gulper shark 16. Basking shark 17. School shark (aka Tope shark) 18. Bluegray Carpetshark 19. Porbeagle shark 20. Whale Shark

Chondrichthyes & Human Hunters. Human Hunters a. The natural enemies of sharks include other...

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