Effects of Shrimp farming on Mangroves

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Effects of Shrimp farming on Mangroves
SWES 474/574 Pamila Ramotar, Ashlee Rhudy and
Thomas Benson
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Contents

• Introduction
• Impacts of shrimp farming
• Shrimp diseases
• Benefits of Aquaculture
• Mitigating effects
• Conclusions

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Introduction

• Mangrove forests support a wealth of life, from
  crustaceans to people, and most importantly the
  health of the planet.
• Forests mangroves form are among the most
  productive and biologically complex ecosystems on
  Earth.
• Mangroves are evergreen trees and shrubs that are
  well adapted to their salty and swampy habitat.
• They having breathing roots (pneumatophores) that
  emerge from the oxygen-deficient mud to absorb
  oxygen.
• Their location combined with their low perceived
  value makes mangrove forests prime targets for
  shrimp farm development.
• Mangroves provide nursery grounds for fish and
  shrimp

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• One of the greatest threats to mangrove survival
  comes from shrimp farming.
• At first glance, shrimp might seem the perfect
  export for a poor country in a hot climate
• Rich countries have an insatiable appetite for it
  (shrimp has overtaken tuna to become America's
  favorite seafood),
• The developing world has the available land and
  right climate to farm it.
• A prime location for shrimp ponds, though,
  happens to be the shore zone occupied by
  mangroves, marshes or mainly salty flats
• The relative to low ecological value of tropical
  and subtropical marshes and salt flats, have been
  conceived as coastal wastelands with low
  ecological and economic value.
• This has led to of loss of marshes through land
  development or modification for use in shrimp
  farming.
• Few attempts have been made to value salt marshes
  in economic and ecological terms
• To compound matters, shrimp farmers typically
  abandon their ponds after a few crop cycles (to
  avoid disease outbreaks and declining
  productivity) and move to new sites, destroying
  more mangroves as they go.

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• Mangrove depletion is associated with shrimp
  aquaculture in Asia and Central America.
• Large areas of mangrove wetlands have been
  converted into milkfish and shrimp farms and
  includes
• in the Philippines (205,523 ha) (Chua 1992)
• Indonesia (211,000 ha) (Chua 1992).
• 69,400 ha in Thailand (Dierberg and
  Kiattisimkul 1996)
• 102,000 ha in Vietnam (Primavera 1998)
• 6500 ha in Bangladesh (Primavera 1998)
• 21,600 ha in Ecuador (Alvarez and others 1989)
• 11,515 ha in Honduras (Stonich 1995, De Walt and
  others 1996).

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Impacts General

• The siting locations for shrimp pond
  construction
• In extensive systems farms are located near
  the shore line to take advantage of the tide to
  collect post larvae, large hectares of mangroves
  are destroyed.
• the management and technology applied during the
  operation of shrimp ponds
• the size or scale of the production and the
  surface dedicated to it, and
• Depend on whether the farms would be extensive,
  semi intensive and intensive based on the systems
  used it would determine the management and
  technology used.

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Impacts General

• Seepage of brackish water from the culture ponds
  into groundwater supplies
• The impact associated with intensive shrimp
  culture is the seepage of brackish water from the
  culture ponds into groundwater supplies and
  adjacent rice paddy fields.
• In some locations in Thailand, new shrimp pond
  construction occurs behind mangrove zones where
  freshwater wetlands and rice-growing areas are
  affected by surface and subsurface saltwater
  intrusion generated by pumping groundwater to the
  ponds.
• This leads to social costs, such as a reduction
  in domestic and agricultural water supplies,
  decreases in fish production, further
  marginalization of coastal fishermen, and
  displacement of labor
• The use of groundwater has resulted in land
  subsidence.

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Impacts Effluents and Shrimp Pond

• Effluents from shrimp ponds are enriched in
  suspended solids, nutrients, and biochemical
  oxygen demand (BOD) with concentrations largely
  depending on whether the management is extensive,
  intensive or semi intensive
• Studies have clearly shown that BOD, ammonia,
  chlorophyll a, and total suspended solids
  increase with stocking density
• extensive shrimp ponds produce few wastes, semi
  intensive ponds produce intermediate waste loads.
• the degree of intensification, i.e., higher
  stocking density ,use of water, feeds and
  fertilizers, produces an increased waste load.
• When effluents derived from agriculture,
  industry, and municipal areas are combined,
  sources of good quality water are sometimes
  scarce.
• When weather and tidal conditions (i.e., cloudy
  days, low winds, and neap tides) are combined,
  the result is a critical degradation of water
  quality in the shrimp ponds and the adjacent
  estuarine/lagoon waters.

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Impacts Capture of Wild Post larvae and Wild
Shrimp Stocks

• Mortality of shrimp fry bycatch, loss of mangrove
  ecosystems, and genetic degradation of native
  populations may all contribute to a decline in
  biodiversity .
• During the 1980s and 1990s, about 35 of the
  world's mangrove forests had vanished.
• Shrimp farming was a major cause of this,
  accounting for over a third of it.
• Mangroves, through their roots, help stabilize a
  coastline and capture sediments their removal
  has led to a marked increase of erosion and less
  protection against floods.

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Shrimp Farming and disease

• Its an aquaculture business used to raise shrimp
  for human consumption
• World production is close to 800,000 metric tons,
  about 30 from shrimp raised on farms in more
  than 50 countries.
• It is estimate that farmed shrimp will account
  for more than 50 of total global production
  within the next five years.
• While approximately 99 of farmed shrimp are
  raised in developing countries, almost all of it
  is exported and consumed in rich, industrial
  countries - the US, Western Europe, and Japan.
• Since 1993 shrimp farming has encountered many
  issues that is believe to be viral diseases
  and is the main reason for the collapse of the
  industry.

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Cultured Systems

• There are three types of systems used to raised
  and culture shrimp.
• Intensive culture system the shrimp are raised
  in high density and insensitively managed tanks
  and ponds
• Semi-intensive system the shrimp are raised in
  moderate densities with some management in cages
  and ponds
• Extensive systems Shrimp are raised in low
  density ponds or tanks with little management in
  natural bodies of water
• In Intensive and some semiintensive systems
  prevention and treatment of disease is possible,
  however because of the high density of these
  systems it aids the development and transmission
  of the diseases.
• In extensive systems treatment is impractical.

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Diseases

• Shrimp are susceptible to protozoa, fungi,
  bacteria, and viral diseases.
• Antibiotics can be used to combat protozoa, fungi
  and bacteria caused diseases
• 11 different virus disease of shrimp
• Consisting of three parvo-like, 2 reo-like,
  toga-like virus, and many baculoviruses
• The major pathogen in china is IHHNV (hypodermal
  and hematopoietic necrosis virus), which is a
  parvo-like virus that causes high mortality rates
  in juvenile shrimp

This picture shows Shrimp with IHHNV disease
which is seen in the bent rostrums
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• They found that there is an occurrence with
  affected areas and the nutrient content of the
  estuary
• Due to less rain and run-off the salinity of the
  estuaries is high and in range to grow bacteria
• Also the decrease in river flow cause nutrients
  to build up in the estuaries causing nutrient
  loading.

This picture shows shrimp with the white spot
virus.
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Measures taken to prevent disease

• Disinfecting the farming ponds before stocking
• Enriching nutrition in the estuaries
• Improving ecological conditions
• Improving water quality (grow in low salinity
  water)
• Supplying high quality feeds to the shrimp
• They also use polyculture

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Polyculture

• The main system used is the shrimp-fish system.
• This helps because the fish eat the sick and
  infected shrimp stopping disease transmission and
  improving the balance in the ecology of the pond.
  
• Problem The fish may cause shrimp survival to be
  low.

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Capture of wild postlarvae

• Wild fry provides seed for many shrimp farms
• Collection of wild fry can lead to bycatch waste
  which hurts local fish populations
• Can have devastating effect on weaker ecosystems

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Benefits of aquaculture

• Aquaculture is a sustainable global seafood
  source
• Important economic role in developing countries
• Provides millions of jobs worldwide
• Little to no effect on local marine populations

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Benefits Continued

• Aquaculture can reduce pressure from commercial
  fishers
• Applicable to a variety of fish and crustacean
• Year round production provides room for world
  population growth

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Sustainable aquaculture

• Can be obtained through practices that are
  environmentally no degrading, economically viable
  and socially acceptable
• Proper management and regulations are key
• Biggest inhibitor is lack of knowledge worldwide

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Mitigating the impacts - Effluent

• The polyculture of bivalve mollusks, fish, and
  shrimp, using pond water to feed oysters,
  mussels, and seaweed in the effluent streams
• Use of shrimp farm effluents to irrigate salt
  tolerant crops. Glenn and others (1991) and Brown
  and others (1999) found that various plants in
  low salinities (Salicornia bigelovii, Atrilplex,
  Distichlis) and high salinities (Suaeda esteroa)
  remove nitrogen from shrimp effluents effectively.

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Mitigating the impacts - Shrimp pond

• The alternatives for use are
• To convert to salt ponds
• Culture of other species (shellfish and crabs)
• To restore the ponds for halophyte and/or
  mangrove plantings.

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Mitigating the impacts

• Pond Designs
• Improved pond designs (Dierberg and Kiattisimkul
  1996, Sandifer and Hopkins 1996), construction of
  wastewater oxidationsedimentation ponds,
• Reduction of water exchange rates are also
  examples of actions to mitigate water quality
  deterioration.
• Improving the method for feed supply (Paez-Osuna
  and others 1998)
• Improve the nutrient composition of the feed
  (Avnimelech 1999) could be an effective strategy
  for lowering the load of nitrogen and phosphorus
  released into the environment.
• Another alternative is to use mangrove wetlands
  as filters of pond effluents prior to their
  release into adjacent waters.

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Mitigating the impacts - Capture of Wild
Postlarvae and Wild Shrimp Stocks

• Regulate wild fry by catch by establishing
• suitable sites,
• periods,
• catch effort
• stimulating the use of hatchery post larvae.

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Conclusions

• Shrimp farming has caused social dislocation,
  ecological change, and environmental destruction
  that is arguably worse
• Serious environmental problems include the
  destruction of coastal wetlands, water pollution,
  disruption of hydrological systems, introduction
  of exotic species, and depletion and salinization
  of aquifers.
• Most critical social problems identified by local
  peoples is the loss of communal resources -
  including mangrove areas, estuaries, and fishing
  grounds - that local people depend on for both
  subsistence and commercial economic activities.

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Best Management practices 1. Pond
preparation 2. Good quality seed selection 3.
Water quality management 4. Feed management 5.
Health monitoring/Biosecurity 6. Pond bottom
monitoring 7. Disease management 8. Better
Harvest and post-harvest Practices 9. Record
maintenance/Traceability 10. Environmental
awareness and instituted educational programs
helps to promote suitable shrimp farming
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Income from pre-existing livelihood activities
like fishing and farming may be affected
negatively by the loss of habitat and
environmental degradation. Benefits related to
broadening the economic base of rural areas,
generating local employment, enhancing food
security, and conserving local environments
Mangrove protection laws are enacted in many
countries New farms are usually of the
semi-intensive kind, which are best constructed
outside mangrove areas There is a trend to
create tightly controlled environments in the
farms, with the hope to achieve better disease
prevention
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• Waste water treatment has attracted attention
  modern shrimp farms have effluent treatment ponds
  where sediments are allowed to settle at the
  bottom and other residuals are filtered.
• Low-intensity polyculture farming for some areas
  are recommended
• Mangrove soils are effective in filtering waste
  waters and tolerate high nitrate levels,
• The industry has also developed an interest in
  mangrove reforestation

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References

• Alongi, D. M., K. G. Boto, and A. I. Robertson.
  1992. Nitrogen and phosphorus cycles. Pages
  251292 in A. I. Robertson and D. M. Alongi
  (eds.), Tropical mangrove ecosystems. American
  Geophysical Union Press, Washington, DC.
• Alvarez, A., B. Vazconez, and L. Guerrero. 1989.
  Multi-temporal study of mangrove, shrimp farm and
  salt flat areas in the coastal zone of Ecuador,
  through information provided by remote sensing.
  Pages 141146 in S. Olsen and L. Arriaga. (eds.),
  Establishing a sustainable shrimp mariculture
  industry in Ecuador.
• Boto, K. G. 1992. Nutrients and mangroves. Pages
  138145 in D. W. Connell and D. W. Hawker (eds.),
  Pollution in tropical aquatic systems. CRC Press,
  Boca Raton, Florida.
• Boyd, C. E., and J. W. Clay. 1998. Shrimp
  aquaculture and the environment. Scientific
  American 2785865.
• Boyd, C. E., and L. Massaut. 1999. Risks
  associated with the use of chemicals in pond
  aquaculture. Aquacultural Engineering 20113132.
• Alongi, D. M., K. G. Boto, and A. I. Robertson.
  1992. Nitrogen and phosphorus cycles. Pages
  251292 in A. I. Robertson and D. M. Alongi
  (eds.), Tropical mangrove ecosystems. American
  Geophysical Union Press, Washington, DC.
• Alvarez, A., B. Vazconez, and L. Guerrero. 1989.
  Multi-temporal study of mangrove, shrimp farm and
  salt flat areas in the coastal zone of Ecuador,
  through information provided by remote sensing.
  Pages 141146 in S. Olsen and L. Arriaga. (eds.),
  Establishing a sustainable shrimp mariculture
  industry in Ecuador.
• Boto, K. G. 1992. Nutrients and mangroves. Pages
  138145 in D. W. Connell and D. W. Hawker (eds.),
  Pollution in tropical aquatic systems. CRC Press,
  Boca Raton, Florida.
• Boyd, C. E., and J. W. Clay. 1998. Shrimp
  aquaculture and the environment. Scientific
  American 2785865.
• Boyd, C. E., and L. Massaut. 1999. Risks
  associated with the use of chemicals in pond
  aquaculture. Aquacultural Engineering 20113132.
• Boyd, C. E., P., Munsiri, and B. F. Hajek. 1994.
  Composition of sediment from intensive shrimp
  ponds in Thailand. World Aquaculture 255355.
• Brown, J. J., and E. P. Glenn. 1999. Management
  of saline aquaculture effluent through the
  production of halophyte crops. World Aquaculture
  304449.
• Brown, J. J., E. P. Glenn, K. M, Fitzsimmons, and
  S. Smith. 1999. Halophytes for the treatment of
  saline aquaculture effluent. Aquaculture
  175255268.

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• Dierberg, F. E., and W. Kiattisimkul. 1996.
  Issues, impacts, and implications of shrimp
  aquaculture in Thailand. Environmental Management
  20649666.
• Flaherty, M., and C. Karnjanakesorn. 1995. Marine
  shrimp aquaculture and natural resource
  degradation in Thailand.Environmental Management
  192737.
• Glenn, E. P., J. W. OLeary, M. C. Watson, T. L.,
  Thomas, and R. O., Kuehl. 1991. Salicornia
  bigelovii Torr An oilseed halophyte for seawater
  irrigation. Science 25110651067.
• Hopkins, J. S., P. A. Sandifer, M. R. DeVoe, A.
  F. Holland, C. L. Browdy, and A. D. Stokes. 1995.
  Environmental impacts of shrimp farming with
  special reference to the situation in the
  continental United States. Estuaries 1825 42.
• Hopkins, J. S., R. D. Hamilton, P. A. Sandifer,
  C. L. Browdy, and A. D. Stokes. 1993. Effect of
  water exchange rate on production water quality,
  effluent characteristics and nitrogen budgets of
  intensive shrimp ponds. Journal of the World
  Aquaculture Society 24303320.
• King, S. E., and J. N. Lester. 1995. The value of
  salt marsh as a Sea defence. Marine Pollution
  Bulletin 30180 189.
• Lightner, Donald V. "Diseases of Cultured Penaeid
  Shrimp." CRC Handbook of Mariculture Crustancean
  Aquaculture. 2nd ed. CRC, 1993. 393-444. Print.
• Martinez-Cordova, L. R., M. A. Porchas-Cornejo,
  H. VillarealColmenares, J. A. Calderon-Perez,
  and J. E. Naranjo-Paramo. 1998. Evaluation of
  three feeding strategies on the culture of white
  shrimp Penaeus vannamei Boone 1931 in low water
  exchange ponds. Aquacultural Engineering 1721
  28.
• Paez-Osuna, F., S. R. Guerrero-Galvan, A. C.
  Ruiz-Fernandez, and R. Espinoza-Angulo. 1997.
  Fluxes and mass balances of nutrients in a
  semi-intensive shrimp farm in north-western
  Mexico. Marine Pollution Bulletin 34290 297.
• Paez-Osuna, F., S. R. Guerrero-Galvan, and A.
  C. Ruiz-Fernandez. 1998. The environmental
  impact of shrimp aquaculture and the coastal
  pollution in Mexico. Marine Pollution Bulletin
  366575.
• Paez-Osuna, F., S. R. Guerrero-Galvan, and A.
  C. Ruiz-Fernandez. 1999. Discharge of nutrients
  from shrimp farming to coastal waters of the Gulf
  of California. Marine Pollution Bulletin
  38585592.