Aquaculture and Biodiversity Conservation

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Aquaculture and Biodiversity Conservation

• James S. Diana
• University of Michigan
• Aquaculture CRSP

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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

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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
  combined35 from aquaculture

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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

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Recent Trends in Aquaculture and Fisheries
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12.5
FAO 2005
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Future Trends in Aquaculture and Fisheries
202573
2011 50
FAO data and Diana projection
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Top 24 Species Produced Globally
Portion of wild fishery used for aquaculture feeds
From Aaron McNevin (WWF)
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Trends in cod and anchoveta (MMT)
FAO 2005
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Tuna yields (TMT)
FAO 2005
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Proportional culture of species in 2000
FAO 2005
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Changes in culture yields (MMT)
FAO 2005
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Trends in 3 cultured species (TMT)
FAO 2005
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Global Significance of U.S. Freshwater Species
Trends in aquatic biodiversity in the U.S.
Master et al. 1998 (TNC)
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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)

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Proportion of U.S. Species at Risk
Master et al. 1998 (TNC)
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Number of species and endangered species by state
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Known Causes of Animal Extinctions
Cox 1993
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Distributions of exotic fishes
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Changes in shared species among pairs of
statesHOMOGENIZATION
Rahel 2000
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Number of events changing species in a state
Rahel 2000
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Relative Importance of Aquaculture Impacts
Positive and negative aspects of aquaculture
Boyd et al. 2005
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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

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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

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Negative Impacts Invasive species
Virtually all of these traits are ones favored
for species used in aquaculture!
Ricciardi Rasmussen 1998
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Negative Impacts Invasive species

• Tilapia is poster child
• More than half of documented introductions were
  not result of aquaculture but natural stocking
  (Canonico et al. 2005)
• Many species also spread by aquarium trade and
  dumping

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Negative Impacts Invasive species

• Factors limiting escapee impacts
• Most fish have been little domesticated that is,
  they are essentially wild fish

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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

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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

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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

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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

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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

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Negative impacts - land use change

• Poster child is loss of coastal mangroves to
  shrimp culture

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Mangroves and shrimp culture
FAO 2005
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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

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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

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Abandoned shrimp ponds and society

• 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

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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)
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Fishmeal Species Produced Globally
Portion of wild fishery used for aquaculture feeds
From Aaron McNevin (WWF)
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Aquacultures Share of Small Pelagics
From Aaron McNevin (WWF)
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Trends in anchoveta (MMT)
FAO 2005
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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

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Changes in Atlantic salmon yields
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Environmentally friendly aquaculture systems
Intensive pond culture system
Liquids
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Catfish tilapia co-culture
Only works where both species are native or very
common!
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Tilapia-tilapia co-culture

• 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

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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

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Added revenue from new plant crop
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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