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Sustaining Aquatic
Biodiversity
Lake Victoria
 lost
endemic fish species due to large
introduced predatory fish.
 Clogged with water hyacinth
Reasons for Lake Victoria’s loss of
biodiversity:

Introduction of Nile perch for sport fishing
• Ate majority of other fish



Lake experienced algal blooms from nutrient
runoff.
Invasion of water hyacinth has blocked sunlight
and deprived oxygen.
Nile perch is in decline because it has eaten its
own food supply.
AQUATIC BIODIVERSITY
3

general patterns
The greatest marine biodiversity occurs in:
• coral reefs,
• estuaries
• ocean floor.


Biodiversity is higher near the coast than open
sea because of habitat and food source variety
Biodiversity is higher is higher on the ocean
bottom than surface
AQUATIC BIODIVERSITY
 Provides
important ecological and economic
services.

Twice that of cropland
 About
½ world’s population relies on ocean
for main food source.
 Chemical compounds: many medical uses

Antibiotic, anticancer, hypertension, bone
reconstruction
HUMAN IMPACTS ON AQUATIC
BIODIVERSITY







Human activities have destroyed, disrupted or
degraded a large proportion of the world’s coastal,
marine and freshwater ecosystems.
H – habitat loss
I – invasive species
P – population growth
P – pollution
C – climate change
O – overharvesting
Habitat Destruction
 Coral


Approximately 20% of the world's coral reefs
have been destroyed.
58% severely damaged
 Sea


reef
grass & kelp beds
Provides habitat, food source, erosion protection
Disappearing at alarming rate
Habitat Destruction
 Mangrove


Forests
We have destroyed more than 1/3 of the world’s
mangrove forests
Critical for habitat, beach erosion protection,
storm surge protection, & flood control
Habitat Destruction
 Coastal



Wetlands
We have destroyed more than 1/2
Mainly beach development: houses, resorts
Critical for habitat, beach erosion protection,
storm surge protection, & flood control
Habitat Destruction
 Ocean




bottom
Being destroyed by dredging and trawler fishing
boats
“Plowing” the sea bed
Takes decades to centuries to recover
Scientists call it the most destructive fishing
practice
Figure 12-2
HUMAN IMPACTS
 Area
of ocean before and after a trawler net,
acting like a giant plow, scraped it.
Figure 12-2
Invasive Species
 Invasive




species are an increasing threat
Arrive in ballast from ships, dumped aquariums,
or intentional released
Bioinvaders are blamed for about 2/3 of fish
extinctions in the U.S. between 1900-2000.
Asian Swamp Eel: rapid reproduction, burrows
into mud banks, wriggles across dry land
Purple Loosestrife: called purple plague,
spreads rapidly
Population Growth and Pollution
 Almost
1/2 of world’s people live on or near
a coastal zone
 80% of ocean water pollution comes from
land-based human activities.



Fertilizer runoff causes algae blooms & fish
die-offs
Industrial waste
Trash
Population Growth and Pollution
 Each
year plastic items dumped from ships
and left as litter on beaches threaten marine
life.
Climate Change
 Ocean


levels rising
Melting ice
Thermal expansion of water
 Changing


weather patterns
More rain in some / less rain in other
Flooding / drought
 Increased
frequency & intensity of storms
Climate Change
 Ocean




Levels
During the past 100 years, sea levels have risen
10-25 centimeters.
Levels are predicted to continue to rise
Coastal cities at risk
Maldives
• Low lying chain of islands in Indian ocean
• Threat of being submerged
Overfishing

Several decades of
overfishing in all of the
world’s oceans has pushed
commercially important
species, e.g. cod, into steep
declines from which
recovery is unlikely.

In 1992, Canada’s 500 year old
cod fishery collapsed,
destroying 40,000 jobs

Total ban on fishing

Stocks still have not recovered
Fishing fleet
Fish market, Norway
Harvesting of Fish and Shellfish

Fishery- a commercially harvestable population
of fish within a particular ecological region.
 Fishery collapse- the decline of a fish population
by 90% or more.
 Bycatch- unintentional catch of non-target
species.
Summary





Marine fisheries are an important biological and
cultural resource
Significant numbers of stocks are overexploited or
depleted
Overfishing is a major cause for the decline of marine
fisheries
Traditional fisheries management has not resulted in
sustainable fisheries
New approaches include both market-based and
ecosystem-based solutions
NOAA Photo Library / OAR/National Undersea Research Program (NURP); Alaska Department of Fish and Game
What is a fishery?
 The
resource (fish species)
 The habitat
 The people involved
NOAA Photo Library –Kip Evans
ARC Centre of Excellence for Coral Reef Studies / Marine Photobank
NOAA Photo Library
Most fish are harvested within 200 miles
of shore
 Upwellings
 Continental
shelves
 Estuaries
NEFSC (NOAA)
NASA, MODIS Rapid Response Team
Sustainable Yields
 The
maximum sustainable yield (MSY) has
been exceeded by too many vessels catching
too many fish, especially fish of reproductive
age, often using wasteful and destructive
methods

Bycatch: unwanted species thrown back into sea
dead or dying
 Modern
industrial fishing can cause 80%
depletion of a species in 10-15 years
NCSR
Overfishing

The build up of large scale fishing fleets has contributed to
widespread overfishing and damage to the marine
environment.
Bottom trawls and dredges cause large scale physical damage
to the sea floor. Sea mounts are particularly vulnerable.
Lost fishing gear (particularly drift nets) threatens marine life,
including birds and mammals that are non-target species.
Purse seines can catch whole schools of fish and non-target
species (bycatch)
Drift net
Purse seine
Fish farming
in cage
Trawl flap
Trawler
fishing
Spotter airplane
Sonar
Purse-seine fishing
Trawl
lines
Trawl bag
Long line
fishing
Fish
school
Drift-net fishing
Float Buoy
Lines with
hooks
Deep sea
aquaculture cage
Fish caught
by gills
Fig. 12-A, p. 255
Status of Marine Fisheries
• In 2004, 52% of world fish stocks
were fully exploited, 25% were
overexploited or depleted
• Large predatory fish have declined
globally by 90%
• At least 42% of U.S. fisheries are
being overexploited
UNFAO– Antonio Pais
Fisheries Collapses
Atlantic cod
Atlantic salmon
Pacific sardine
Haddock
Atlantic halibut
Collapse of the Atlantic Cod Fishery off Newfoundland
Millennium Ecosystem Assessment
Peruvian
anchovy
Bluefin Tuna
Causes for Marine Fishery Declines
• Overfishing
The rate of fish mortality (harvest plus
bycatch) exceeds the natural rate
of replacement.
• Highly efficient technology
Fishing vessels and gear
Radar and sonar
Electronic navigation
Aircraft with infrared sensors
• Bycatch
The capture of non-target
fish or other marine animals
in fishing gear
• Overcapacity
Fishing fleets are larger
than necessary to harvest
the allowable catch
NOAA Photo Library – Teobaldo Dioses
Fishing Down the Food Web
The serial harvest of progressively lower trophic levels
Trophic
Level
Time
Concept : Daniel Pauly; Artist: Aque Atanacio
Habitat Degradation:
the impact of fishing gear
Before
trawling
After
trawling
Deep-sea Oculina coral reefs off Florida's Atlantic Coast
Overfishing and Extinction:
Gone Fishing, Fish Gone
 About
75% of the world’s commercially
valuable marine fish species are over fished
or fished near their sustainable limits.




Big fish are becoming scarce.
Smaller fish are next.
We throw away 30% of the fish we catch.
We needlessly kill sea mammals and birds.
Why is it Difficult to Protect Aquatic
Biodiversity?




Human ecological footprint is expanding.
Much of the damage to oceans is not visible to
most people.
Many people incorrectly view the oceans as an
inexhaustible resource.
Most of world’s ocean lies outside legal
jurisdiction
PROTECTING MARINE BIODIVERSITY
 Laws,
international treaties, and education
can help reduce the premature extinction of
marine species.

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1975 CITIES
1979 Global Treaty on Migratory Species
1972 Marine Mammal Protection Act
1973 Endangered Species Act
1976 US Whale Conservation & Protection Act
1995 International Convention on Biological
Diversity
1996 US Sustainable Fisheries Act
IWC – International Whaling Commission
The Florida Manatee and Water
Hyacinths
 Manatee
can eat
unwanted Water
Hyacinths.
 Endangered due to:





Habitat loss.
Entanglement from fishing
lines and nets.
Hit by speed boats.
Stress from cold.
Low reproductive rate
Figure 12-B
Commercial Whaling
of 11 species – hunted to commercial
extinction.
 Blue whale – to brink of biological extinction
 1970 – US stopped whaling & banned all
whale imports
 International Whaling Commission (IWC)
banned commercial whaling in 1986
8
Case Study:
Commercial Whaling
 Despite
ban, Japan,
Norway, and Iceland kill
about 1,300 whales of
certain species for scientific
purposes.

Although meat is still sold
commercially.
 Hope
to reverse
international ban
Revamping Ocean Policy
 Two
recent studies called for an overhaul of
U.S. ocean policy and management.

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Develop unified national policy.
Double federal budget for ocean research.
Centralize the National Oceans Agency.
Set up network of marine reserves.
Reorient fisheries management towards
ecosystem function: Catch Limits
Increase public awareness.
Market-based Solutions
 Certification
 Consumer-based
solutions
 Purchase of fishing rights
 Aquaculture
 Increased use of underutilized species
 Reduce government subsidies
Ecosystem-based Fishery
Management
Attempts to sustain healthy marine ecosystems
and the fisheries they support
 Reduce
bycatch
 Marine reserves
 Catch share programs
 Ecologically sustainable yield
PROTECTING MARINE BIODIVERSITY
 Six
of the world’s seven major turtle species
are threatened or endangered because of
human activities.
 Since 1989 the U.S. government has
required offshore shrimp trawlers to use turtle
exclusion devices.


Sea turtle tourism brings in almost three times as
much money as the sale of turtle products.
Reconciliation ecology
MARINE SANCTUARIES
 Fully
protected marine reserves make up less
than 0.3% of the world’s ocean area.

Studies show that fish populations double, size
grows by almost a third, reproduction triples and
species diversity increases by almost one fourth.
 Call
for 30% protected
 Some communities work together to develop
integrated plans for managing their coastal
areas.

1975 Australia’s Great Barrier Reef;1/3 protected
Marine Reserves
Extractive activities (fishing, mining, oil drilling) are prohibited in
marine reserves
Some good news for a change?
COMPASS, E. Neeley
Catch Share Programs
Limited Access Privilege Programs – LAPPs
Individual
Transferable
Quotas (ITQs)
can be bought
and sold
Bluefin tuna harvest in Spain
UNFAO / NOAA Photo Library / Jose Cort
Have been used
successfully to
increase fish
populations and
reduce
fisherman’s costs.
Solutions
Managing Fisheries
Fishery Regulations
Bycatch
Set catch limits well below the
maximum sustainable yield
Use wide-meshed nets to allow
escape of smaller fish
Improve monitoring and enforcement
of regulations
Economic Approaches
Use net escape devices for sea
birds and sea turtles
Sharply reduce or eliminate fishing
subsidies
Ban throwing edible and
marketable fish back into the sea
Aquaculture
Charge fees for harvesting fish and shellfish
from publicly owned offshore waters
Restrict coastal locations for fish
farms
Certify sustainable fisheries
Protected Areas
Control pollution more strictly
Establish no-fishing areas
Depend more on herbivorous fish
species
Establish more marine protected areas
Nonnative Invasions
Rely more on integrated coastal
management
Kill organisms in ship ballast water
Consumer Information
Label sustainably harvested fish
Publicize overfished and threatened species
Filter organisms from ship ballast
water
Dump ballast water far at sea and
replace with deep-sea water
Fig. 12-7, p. 261
Aquaculture
• Aquaculture- the
farming of aquatic
organisms such as
fish, shellfish, and
seaweeds.
• Raising marine and
freshwater fish in
ponds and
underwater cages
• like a feedlot for
fish
Aquaculture
China and India are the world leaders in aquaculture production.
Over 200 fish and shellfish species are grown in aquaculture.
Freshwater fish such as carp and their relatives dominate global production,
the most common marine species include shrimp, salmon, oysters, clams and mussels.
In the U.S., 5 of the top 10 species (shrimp, salmon, catfish, tilapia and clams) consumed
in 2004 were at least partially produced in aquaculture operations.
While aquaculture has the potential to reduce pressure on wild-caught fish, this has not
yet been realized. Ironically, it may do just the opposite, particularly when fish at
higher trophic levels are raised such as bluefin tuna or salmon. These fish require a
diet that contains animal protein. When farmed fish are fed fish meal, fishing effort is
often required to get enough food to feed these captive fish. To feed fish and shrimp,
growers typically rely on wild-caught ocean fish. For example, about 3 metric tons of
wild-caught fish are required to produce 1 metric ton of farmed shrimp or
salmon.
Despite these shortcomings, aquaculture is likely to play an increasingly important role
in meeting the ever-increasing global demand for seafood. Farmed organisms that do
not consume fish meal hold the most promise for a sustainable fishery – e.g., mussels,
clams, tilapia (an herbivorous fish).
Aquaculture
• Pros:
–
–
–
–
Efficient: less water/space, more fish,
Potential to take pressure off wild species
Low fuel usage, high profits
Potential sustainable protein source &
economic development
• Cons:
– Need feed, water, antibiotics
– Produces lots of waste, may destroy
estuaries and wetlands,
– need fish to feed fish (lose 90% moving up
trophic level),
– dense populations increase disease &
parasites which can spread to wild fish
– bioaccumulation of toxins (PCBs,
mercury, dioxins, etc) if benthic soil is
contaminated
• Possible solution – aquaculture in the
open ocean or way inland
PROTECTING, SUSTAINING, AND
RESTORING WETLANDS
 US
has lost ½ of wetlands
 Federal permit is required to develop
wetlands – has cut wetland loss by 80%
 Attempts by developers to weakened this law
 Mitigation – allows destruction of existing
wetland as long as equal area of same type
is created or restored
Figure 12-8
Solutions
Protecting Wetlands
Legally protect existing wetlands
Steer development away from existing wetlands
Use mitigation banking only as a last resort
Require creation and evaluation of a new wetland before
destroying an existing wetland
Restore degraded wetlands
Try to prevent and control invasions by nonnative species
Fig. 12-9, p. 264
Restoring the Florida Everglades
 The
world’s largest ecological restoration
project involves trying to undo some of the
damage inflicted on the Everglades by
human activities.




90% of park’s wading birds have vanished.
Other vertebrate populations down 75-95%.
Large volumes of water that once flowed through
the park have been diverted for crops and cities.
Runoff has caused noxious algal blooms.
Restoring the
Florida
Everglades
 The
project has
been attempting
to restore the
Everglades and
Florida water
supplies.
Figure 12-10
PROTECTING LAKES AND RIVERS
 For
decades, invasions by nonnative species
have caused major ecological and economic
damage to North America’s Great lakes.

Sea lamprey, zebra mussel, quagga mussel,
Asian carp.
PROTECTING LAKES AND RIVERS
 Dams
can provide many human benefits but
can also disrupt some of the ecological
services that rivers provide.



119 dams on Columbia River have sharply
reduced (94% drop) populations of wild salmon.
U.S. government has spent $3 billion in
unsuccessful efforts to save the salmon.
Removing hydroelectric dams will restore native
spawning grounds.
PROTECTING LAKES AND RIVERS
A
federal law helps protect a tiny fraction of
U.S. wild and scenic rivers from dams and
other forms of development.

National Wild and Scenic Rivers Act (1968).
Natural Capital
Ecological Services of Rivers
• Deliver nutrients to sea to help sustain
coastal fisheries
• Deposit silt that maintains deltas
• Purify water
• Renew and renourish wetlands
• Provide habitats for wildlife
Fig. 12-11, p. 267