Transcript Presentation

Aquaculture and Biodiversity
Conservation
James S. Diana
University of Michigan
Aquaculture CRSP
Plans for today
• Overview aquaculture and capture fisheries
• Review some issues about aquatic
biodiversity conservation in the U.S.
• Examine the positive and negative aspects
of aquaculture related to conserving
biodiversity
• Propose a couple of systems that are able to
produce aquatic crops without major threats
to biodiversity
Overview fisheries and aquaculture
Why should we promote aquaculture?
• Fastest growing food production system globally at about
7.42 % increase per year since 1995 (9% 1985 to 1995)
• Can either exacerbate or reduce pressure on wild fisheries
• Increasing number of new species produced by aquaculture
as other stocks decline (cod, hake, halibut, cobia, tuna)
• New industry with significant potential for innovation
• FAO forecasted global increase in seafood consumption of
1.5 kg/person, while catches remain static
• In US, a 1.5-2 billion kg increase in seafood consumption
is anticipated by 2020, all from aquaculture
• Seafood exports generate twice as many $ for LDCs as
coffee, tea, rubber, bananas, rice, meat combined—35%
from aquaculture
What is aquaculture?
• Controlled growing of some
aquatic crop, mainly for food
– Control can vary from complete life
cycle to just placing appropriate
medium for settlement
• Level of inputs (intensity) varies
– Extensive = just raise in appropriate
place
– Semi-intensive = add fertilizer and
control water quality
– Intensive = provide full feed, water
exchange, aeration, other chemicals
Recent Trends in Aquaculture and Fisheries
160
150
38%
Aquaculture
Capture
140
Yield MMT.
130
120
110
12.5%
100
90
80
70
60
50
1980
1985
1990
1995
2000
FAO 2005
Future Trends in Aquaculture and Fisheries
375
350
Yield MMT.
325
300
275
2025
73%
Aquaculture
Capture
2011
50%
250
225
200
175
150
125
100
75
50
1980
1985
1990
1995
2000
2005
2010
2015
2020
2025
FAO data and Diana projection
Production (metric tons x millions)
Top 24 Species Produced Globally
7
Aquaculture
Capture
6
5
4
3
2
1
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Portion of wild fishery used for aquaculture feeds
From Aaron McNevin (WWF)
Trends in cod and anchoveta (MMT)
14
Anchoveta
Atlantic cod
4
10
8
3
6
2
4
1
2
0
1950
0
1960
1970
1980
1990
2000
FAO 2005
Cod Yield.
Anchoveta Yield.
12
5
Tuna yields (TMT)
2,500
60
Skipjack tuna
50
.
Atlantic bluefin tuna
40
1,500
30
1,000
20
500
0
1950
10
1960
1970
1980
1990
0
2000
FAO 2005
Bluefin Harvest
Skipjack Harvest .
2,000
Proportional culture of species in 2000
25
64.5%
Culture Yield MMT .
20
43.7%
15
30.1%
10
5
4.2%
4.8%
3.7%
0
Carps
Salmonids
Tilapias
Finfish
Crustacea
Molluscs
FAO 2005
Changes in culture yields (MMT)
10.8 31.5
Culture Yield MMT .
4
3
1980
1990
2000
2
1
0
Africa
North
South
America America
Asia
Europe
Oceania
FAO 2005
Trends in 3 cultured species (TMT)
1200
1000
Nile tilapia
Atlantic salmon
Giant tiger prawn
800
600
400
200
0
1970
1975
1980
1985
1990
1995
2000
FAO 2005
Trends in aquatic biodiversity in the U.S.
Global Significance of U.S. Freshwater Species
Taxonomic group
U.S.
described
species
Freshwater fishes
Crayfishes
Freshwater mussels
Freshwater snails
Stoneflies
Mayflies
Caddisflies
Dragonflies
Stygobites
801
322
300
600
600
590
1,400
452
327
Worldwide
described
species
8,400
525
1,000
4,000
1,550
2,000
10,564
5,756
2,000
Percent
found in
U.S.
10
61
30
15
40
30
13
8
16
U.S. ranking
in species
diversity
7
1
1
1
1
1
1
Uncertain
1
Master et al. 1998 (TNC)
Why worry about aquatic biodiversity
• Among vertebrates, fish species outnumber
all other vertebrates combined
• Aquatic invertebrates are often sensitive
indicators of pollution problems
• Very high rates of endemism in several
aquatic systems (caves, African great lakes,
some isolated streams)
Proportion of U.S. Species at Risk
Master et al. 1998 (TNC)
Number of species and endangered species by state
Known Causes of Animal Extinctions
Other
2%
Habitat
Disruption
28%
Exotic species
43%
Exploitation
27%
Cox 1993
Distributions of exotic fishes
Frequency
Changes in shared species among pairs of states
HOMOGENIZATION
100
90
80
70
60
50
40
30
20
10
0
-8
-4
0
4
8
12
16
20
24
28
32
36
Change in shared species
Rahel 2000
40
Number of events changing species in a state
80
50
70
Total = 901
40
30
20
10
Number of Extinctions .
Number of Introductions .
60
Total = 196
60
50
40
30
20
10
0
0
0 5 10 15 20 25 30 35 40 45 50
Number of States.
0
5
10
15
Number of States .
Rahel 2000
20
Positive and negative aspects of aquaculture
Relative Importance of Aquaculture Impacts
Species/ Species Groups
Issues
Tuna
Shrimp
Salmon
Trout
Catfish
Tilapia
Abalone
Antibiotic use
M
H
H
H
M
M
M
Benthic biodiversity
H
M
M
M
Chemical use
M
H
M
H
Disease transfer
H
H
H
Escapees/Invasive
H
M
H
Genetic alteration
H
Land and water use
Mortality removal
H
H
H
H
H
H
H
M
M
H
H
Fish meal/oil use
H
H
H
H
M
M
Water pollution
H
H
M
H
M
H
M
M
H
H
H
H
M
Predator control
User conflicts
M
Oysters
Clams
Mussels
M
M
M
M
M
M
M
M
H
M
H
M
H
H
Scallops
M
M
M
H
M
M
M
M
H
H
H
H
M
M
M
M
M
M
H
Boyd et al. 2005
Impacts that Affect Biodiversity (my ranking)
•
•
•
•
•
•
•
Escapement and invasive species
Effluents and water pollution
Land use change
Use of fish meal in feeds
Predator controls
Genetic alteration from escaped organisms
Antibiotic and hormone use
Positive Impacts on Biodiversity
• Production reduces pressure on wild stocks
• Stocking organisms to enhance depleted
stocks
• Effluents and wastes increase production,
abundance, and diversity of species in local
area
• Income generation replaces less sustainable
income generating systems
Negative Impacts – Invasive species
Virtually all of these traits are ones favored for
species used in aquaculture!
Ricciardi & Rasmussen 1998
Negative Impacts – Invasive species
• Tilapia is poster child
• More than half of
documented introductions
were not result of
aquaculture but natural
stocking
• Many species also spread
by aquarium trade and
dumping
(Canonico et al. 2005)
Negative Impacts – Invasive species
• Factors limiting escapee
impacts
– Most fish have been little
domesticated; that is, they are
essentially wild fish
Negative Impacts – Invasive species
• Escapement is
inevitable with
aquaculture species in
almost any system
• Best avoidance is not
culturing outside of
native or common
current range
Negative Impacts – Effluents and Pollution
• Common concern in
cages/pens
– In oligotrophic waters,
actually seems to
increase biodiversity
– Probably a major issue
in eutrophic waters
• We rely on the
assimilative capacity of
waters as an important
ecosystem service
Negative Impacts – Effluents and Pollution
• Oligotrophic studies
– 43 Chilean farms, only negative
effects on benthic invertebrates
in ‘fallout’ zone, much increase
in pelagic diversity and
production
• Soto and Norambuena 2004
– Aegean farms showed increases
in pelagic and benthic fish
diversity and production in
farmed zones
• Machias et al. 2004, 2005
Effluents and pollution
• Clear that impact depends greatly on the
density of fish in cages and of cages in area
• We need to know more about the
assimilative capacity of waters and the
resultant limits to cage culture
• Some pen facilities have the combined
loading of phosphorus and nitrogen
equivalent to domestic discharge of a fairly
large city
Effluent discharge, nutrient loss and pollution
• Effluents can also
be a concern in
ponds, especially
for intensive culture
• May be remediated
by plant co-culture
or by draining and
harvesting
techniques
Negative impacts - land use change
• Poster child is loss
of coastal
mangroves to
shrimp culture
Mangroves and shrimp culture
350
1980
1985
1990
1995
2000
Yield TMT.
300
250
200
150
100
50
0
China
FAO 2005
Taiwan
Ecuador
Thailand
Abandoned shrimp ponds
• Cycle of intensity, disease,
pond failure, and
abandonment
– Results in altered land
– Causes salinization of soils
– Often land taken from other
productive use
Mangrove losses
• Important nursery and
storm buffering area
• Coastal development has
caused large losses (33%)
from many sources,
including pond shrimp
culture (Alongi 2002)
• Many specific studies
show aquaculture and
others are responsible for
mangrove loss
Abandoned shrimp ponds and society
convert
Shrimp
Culture
Poor
Management,
disease and
pollution lead to
• Thai ponds – not
abandoned but cycle of
use
• Most local people
perceive that they have a
better life as a result of
shrimp culture
• Obvious economic
benefits as well as
development of an
industry for rural areas
• Disease and abandonment
has been a major problem
in some countries –
Taiwan, China
Original
agricultural
pursuit (rice,
fish, pigs,
etc.)
Longerterm
options
Collapse
Invest
More
Immediate
Options
Fallow
Abandon
New land use (salt
pan, extensive
culture, housing,
industry, fish)
Rent land
to others
The Fishmeal Issue
• 20-30 MMT of biomass currently harvested to produce
6-7 MMT of fish meal
• Aquaculture uses approximately 50% of all fishmeal and
80% of global fish oil (80 & 95% respectively by 2020)
• Salmon aquaculture uses 2-3% of all fish caught for feed
• Shrimp aquaculture uses 3-4% of all fish caught for feed
• Antarctic krill biomass estimated at 62-137 MMT in
2000 but only 1.5 MMT of krill can be harvested
without impacting krill predators
From Aaron McNevin (WWF)
Production (metric tons x millions)
Fishmeal Species Produced Globally
7
Aquaculture
Capture
6
5
4
3
2
1
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Portion of wild fishery used for aquaculture feeds
From Aaron McNevin (WWF)
Production (metric tons x millions)
Aquaculture’s Share of Small Pelagics
70
Pelagic capture for aquaculture feed
Pelagic capture for other uses
Aquaulture production
60
50
40
30
20
10
0
1973
1978
1983
1988
1993
1998
2003
Year
From Aaron McNevin (WWF)
Trends in anchoveta (MMT)
14
Anchoveta Yield.
12
Anchoveta
10
8
6
4
2
0
1950
1960
1970
1980
1990
2000
FAO 2005
Atlantic Salmon case
• Mainly commercial fishery
• Important and popular sport
fish as well
• Aquaculture began in 1960s
• As aquaculture grew,
pressure on wild fish declined
• Now some rejuvenation of
wild stocks as well
Changes in Atlantic salmon yields
1400000
1200000
18,000
Culture
Capture
16,000
14,000
12,000
800000
10,000
600000
8,000
6,000
400000
4,000
200000
0
1950
2,000
1960
1970
1980
1990
2000
0
2010
Capture Yield
Culture Yield
1000000
Intensivefriendly
pond culture
system
Environmentally
aquaculture
systems
Cage-cum-pond system
Feed
Sediment
Solid waste
Fed fish
Caged
fish
Soluble waste
Water
Waste feed
Phytoplankton
Solids
Open filterFeeders
Liquids
Catfish – tilapia co-culture
mud
23%
others
17%
water
12%
tilapia
13%
catfish
35%
Only works where both species are native or very common!
Tilapia-tilapia co-culture
Caged
fish
37%
Others
22%
Sediment
25%
Water
3%
Pond fish
13%
• Can also work with
other local
combinations of
species, with fed fish
in cages, best when
not using fish meal
feed, and filter feeding
fish in ponds
– Climbing perch – rohu
in Bangladesh
Fish and plant culture
• Many ponds are grown with multiple use in mind
• Can even use in restoring communities
• Value added by second crop can make the
operation successful
Added revenue from new plant crop
Parameter
Open system
Closed system
Recycle system
Prawn
3.88±0.84a
7.20±0.66b
7.07±1.67b
Tilapia
-
-
0.37±0.06
Mimosa
-
-
0.70±0.32
Total Revenue
3.88±0.84a
7.20±0.66b
8.14±1.29b
Mean revenue per tank
3.88±0.84a
7.20±0.66b
2.71±0.43a
2.01±0.02
1.98±0.01
1.96±0.01
Gross revenue
Operation Cost
Prawn juveniles
Tilapia fingerlings
0.25±0.00
Mimosa seedlings
0.25±0.00
Feeds
2.07±0.01a
2.37±0.03b
2.36±0.09b
Urea
0.01±0.00
0.01±0.00
0.01±0.00
TSP
0.01±0.00
0.01±0.00
0.01±0.00
Electricity
0.24±0.00a
1.45±0.00b
1.68±0.00c
Cost of working capital
0.12±0.00a
0.15±0.00b
0.17±0.00c
Total Cost
4.45±0.00a
5.97±0.02b
6.69±0.08b
Mean cost per tank
4.45±0.00b
5.97±0.02c
2.23±0.03a
Net return per tank
-0.57±0.84
1.23±0.64
0.48±0.46
Conclusions
• Older aquaculture crops often used systems
that damaged biodiversity in local area
• Modern certification and organic standards
are forcing aquaculture to use less
damaging systems
• Overall effects have been both positive and
negative to biodiversity, and can be
managed
• Management balance of cost of technology,
benefit in sales, and regulations or forcing
by market