© 2011 pearson education, inc. ap environmental science mr. grant lesson 79 emptying the oceans...

© 2011 Pearson Education, Inc.

AP Environmental Science

Mr. Grant

Lesson 79

Emptying the Oceans

&

Marine Conservation


Mastery Check

Describe three ways plastics affect marine life.


Objectives:

• Define the term marine reserve.

• Review the current state of ocean fisheries and reasons for their decline.

• Evaluate marine protected areas and reserves as innovative solutions.

• TED - Legendary ocean researcher Sylvia Earle shares astonishing images of the ocean -- and shocking stats about its rapid decline -- as she makes her TED Prize wish: that we will join her in protecting the vital blue heart of the planet.


Marine Reserve: A marine protected area that is highly protected, and is effective as a complete sanctuary; no extractive uses are permitted, and very few (or no) other human uses (including scientific research) are permitted.

Define the term marine reserve.


Review the current state of ocean fisheries and reasons for their decline.• Over half the world’s marine fish populations are fully exploited,

28% are overexploited, and only 20% can yield more without declining.

• Global fish catches have stopped growing since the late 1980’s, despite increased fishing effort and improved technologies.

• People began depleting marine resources long ago, but impacts have intensified in recent decades.

• Commercial fishing practices include drift netting, long-line fishing, and trawling, all of which capture non-target organisms, called bycatch.

• Non-target species are killed when they are captured as bycatch while fishing for commercially-valuable species.

• Today’s oceans hold only one-tenth as many large animals that they did before industrialized commercial fishing.


Review the current state of ocean fisheries and reasons for their decline.

• As fishing intensity increases, fish become smaller and fishermen switch to less-desirable species.

• Consumers can encourage good fishery practices by shopping for sustainable seafood.

• Marine biodiversity loss affects ecosystem services.

• Traditional fisheries management has not stopped declines, so many scientists feel that ecosystem-based management is needed.


Emptying the Oceans

Overharvesting is the worst marine problem We are putting unprecedented pressure on marine

resources Half the world’s marine fish populations are fully

exploited and can’t be fished more intensively

28% of fish population are overexploited and heading to extinction

Total fisheries catch leveled off after 1988 despite increased fishing effort

The maximum wild fisheries potential has been reached


Emptying the oceans


The global fisheries catch has increased

It is predicted that populations of all ocean species we fish for today will collapse by 2048


Emptying the Oceans

If current trends continue, it is predicted that populations of all ocean species we fish for today will collapse by 2048

If fisheries collapse as predicted, we will lose their ecosystem services Productivity will decline, and they will become more

sensitive to disturbance

Filtering of water will decline, causing more harmful algal blooms and beach closures

Aquaculture is relieving some of the pressure on wild stocks, but it has its own set of environmental problems


We have long overfished

People began depleting sea life centuries ago

Species have been hunted to extinction: Caribbean monk seal, Steller’s sea cow, Atlantic gray whale

Decreased sea turtle populations cause overgrowth of sea grass and can cause sea grass wasting disease

Overharvesting nearly exterminated many whale species

People never thought groundfish could be depleted Local populations dwindled as far back as the 19th century

New approaches or technologies were needed to increase catch rates


Fishing has industrialized

Factory fishing = huge vessels use powerful technologies to capture fish in huge volumes

Driftnets = transparent nylon mesh nets that drift with the current

Used for herring, sardines, mackerel, sharks, shrimp

Longline fishing = extremely long (up to 80 km or 50 mi) lines with several thousand baited hooks

Used for tuna and swordfish


Fishing has industrialized

Trawling = using cone shaped nets with weights at the bottom and floats at the top to catch pellagic fish

Bottom trawling = using weighted nets that drag across the seafloor to catch groundfish or scallops


Fishing practices kill nontarget animals and damage ecosystems Bycatch = the accidental capture of animals

A 2011 report found that 17% of all commercially harvested fish were captured unintentionally

Driftnetting drowns dolphins, turtles, and seals Fish die on deck

Banned in international waters

But is still used in national waters Longline fishing kills turtles, sharks, and over

300,000 seabirds/year Methods (e.g., flags) are being developed to limit

bycatch


Fishing practices kill nontarget animals

Fisheries bycatch is one of the biggest problems facing the world's oceans


Fishing practices kill nontarget animals and damage ecosystems Dolphins are trapped in nets used to catch tuna

Hundreds of thousands of dolphins were killed

The 1972 Marine Mammal Protection Act forced fleets to try to free dolphins Bycatch dropped dramatically

Other nations fished for tuna, and bycatch increased The U.S. government required that nations exporting

tuna to the United States minimize dolphin bycatch “Dolphin-safe” tuna uses methods to avoid bycatch

Other species (sharks) are still being caught Dolphin populations have not yet recovered


Dolphin deaths have declined, but …


Fishing practices kill nontarget animals and damage ecosystems Bottom trawling causes bycatch and harms entire

ecosystems

Heavy nets crush organisms and damage sea bottoms Especially destructive to complex areas (e.g., reefs)

It equals clear-cutting and strip mining

The average spot of the sea floor in the Georges Bank has been trawled three times, destroying young cod as bycatch

Bycatch of cod while fishing for other species in the Grand Banks nearly doubled from 2006 to 2009


Bottom-trawling destroys ecosystems


Modern fishing fleets deplete marine life rapidly

Grand Banks cod have been fished for centuries Catches more than doubled with industrial trawlers

Record-high catches lasted only 10 years

Georges Bank cod fishery also collapsed


Modern fishing fleets deplete marine life rapidly

Worldwide, industrialized fishing is depleting marine populations with astonishing speed 90% of large-bodied fish and sharks are eliminated

within 10 years after fishing begins

Populations stabilize at 10% of their former levels

Communities were very different before modern fishing Removing animals at higher trophic levels allows prey

to proliferate and change communities


Industrialized fishing is destroying fisheries

Oceans today contain only one-tenth of the large-bodied animals they once did


Modern fleets deplete marine life rapidly


Several factors mask declines

Industrialized fishing has depleted stocks But global catch has remained stable for the past 20 years

How can stability mask population declines? Fishing fleets travel farther to reach less-fished areas

Fleets fish in deeper waters (now at 250 m)

Fleets spend more time fishing and set more nets

Improved technologies: faster ships, sonar mapping, satellite navigation, thermal sensing, aerial spotting

Fleets expend more effort to catch the same number of fish

At some point, there will not be enough fish left


We are “fishing down the food chain”

Figures on total global catch do not tell the whole story

As fishing increases, the size and age of fish caught decline 10-year-old cod, once common, are now rare

As species become too rare to fish, fleets target more abundant species Shift from large, desirable species to smaller, less

desirable ones

This entails catching species at lower trophic levels

“Image makeovers” renamed formerly undesirable fish “Orange roughy” was once called “slimehead”


We are “fishing down the food chain”


Purchasing choices influence fishing practices

Best choices: farmed catfish, mussels, oysters, tilapia


Marine biodiversity loss erodes ecosystem services

Factors that deplete biodiversity threaten ecosystem services we get from the oceans

Systems with reduced species or genetic diversity show less primary and secondary production They are less able to withstand disturbance

Biodiversity loss reduces habitat for nurseries for fish and shellfish

Less diversity leads to reduced filtering and detoxification, resulting in algal blooms, dead zones, fish kills, beach closures


Diversity loss erodes ecosystem services

Accelerating Loss of Ocean

Species Threatens

Human Well-Being.


Fisheries management has been based on maximum sustainable yield Maximizes harvest while maintaining fish for the future

Managers may limit the harvest or restrict gear used

Despite management, stocks have plummeted Requires accurate measurement of fish numbers

Overestimates have resulted in overharvesting

Ecosystem-based management shifts away from species and toward the larger ecosystem Considers the impacts of fishing on habitat quality, species

interactions, and long-term effects

Sets aside areas of oceans free from human interference


Fisheries management

Successful management of summer flounder has resulted in an increase in adult fish stock.


Evaluate marine protected areas and reserves as innovative solutions.

• We have established fewer protected areas in the oceans than we have on land, and most marine protected areas allow many extractive activities.

• No-take marine reserves can protect ecosystems while also boosting fish populations and making fisheries sustainable.


We can protect areas in the ocean

Marine protected areas (MPAs) = most are along the coastlines of developed countries They still allow fishing or other extractive activities

Marine reserves = areas where fishing is prohibited Leave ecosystems intact, without human interference

Improve fisheries, because young fish will disperse into surrounding areas

Many commercial and recreational fishers and businesses do not support reserves To be successful, establishment needs to be sensitive

to concerns of local residents


We can protect areas in the ocean


Reserves can work for both fish and fishers

A 2001 review showed that after just one to two years of establishment, marine reserves: Increased densities of organisms by 91% Increased biomass by 192% Increased organism size by 31% Increased species diversity by 23%

Benefits inside reserve boundaries include: Rapid and long-term increases in abundance,

diversity, and productivity of marine organisms Decreased mortality and habitat destruction Decreased likelihood of extirpation of species


Reserves work for both fish and fisheries



Areas outside reserves also benefit A “spillover effect” occurs when individuals of

protected species spread outside reserves Larvae of species protected within reserves “seed the

seas” outside reserves

Improved fishing and ecotourism


Areas outside reserves also benefit

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&docid=ydZd6qCGftVLbM&tbnid=Dix4y_F7p9AhTM:&ved=0CAUQjRw&url=http://www.piscoweb.org/publications/outreach-materials/science-of-marine-reserves/international-science-of-marine-reserves&ei=lq33UsSVF6ngsASW64LACg&bvm=bv.60983673,d.aWc&psig=AFQjCNHB-LKCd9SQnsLJzA-bFTESmEbdew&ust=1392049855527216



Local residents who were opposed changed to supporting reserves once they saw their benefits

Once commercial trawling was stopped on Georges Bank: Populations of organisms began to recover

Fishing in adjacent waters increased


How should reserves be designed?

Reserves should be able to Protect ecosystems

Sustain fisheries

Include people

Most studies suggest that 20–50% of the ocean should be protected in no-take reserves How large should the reserves be?

How many should we have?

Where should they be located?

Involving fishers is crucial in coming up with answers


How should reserves be designed?


TED Video

Sylvia Earle has been at the frontier of deep ocean exploration for four decades. She's led more than 50 undersea expeditions, and she's been an equally tireless advocate for our oceans and the creatures who live in them.

" We've got to somehow stabilize our connection to nature so that in 50 years from now, 500 years, 5,000 years from now there will still be a wild system and respect for what it takes to sustain us."

Sylvia Earle

Sylvia Earle's TED Prize wish to protect our oceans (18:16)

http://www.ted.com/talks/lang/eng/sylvia_earle_s_ted_prize_wish_to_protect_our_oceans.html

© 2011 pearson education, inc. ap environmental science mr. grant lesson 79 emptying the oceans...

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term marine reserve

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