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Aquaculture Impacts on the Environment
(Released December 1999 )

 
  by Craig Emerson  

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  1. Development of Low-pollution Feeds for Sustainable Aquaculture

    Sugiura, SH

    Dissertation Abstracts International Part B: Science and Engineering [Diss. Abst. Int. Pt. B - Sci. & Eng.], Apr 1999, vol. 59, no. 10, p. 5180

    In order to cope with an ever-increasing world population, it is imperative to find a way to increase world food production and, at the same time, to reduce environmental pollution. The present research has a significant implication since it aimed to achieve both goals simultaneously by developing low-pollution feeds for the world's fastest growing food-producing sector, aquaculture. To determine the minimum dietary requirement of phosphorus for large fish, an original, sensitive and rapid method has been developed. This approach is based upon the urinary excretion of phosphorus of fish placed in a metabolic tank, and the phosphorus requirement can be determined within a few days. Other response parameters for dietary phosphorus were also studied, and were found to be less sensitive than urinary phosphorus concentrations; i.e., concentrations of glucose, glucose-6-phosphate, ATP, creatine phosphate, inorganic phosphorus, calcium, acetoacetate, total lipids, cholesterol, glycogen and alkaline phosphatase in blood, plasma, skeletal muscle, liver and feces. To select feed ingredients based on the nutrient digestibility (availability), the apparent digestibility (availability) of dry matter, protein, phosphorus, calcium, magnesium, sodium, potassium, iron, copper, manganese, zinc and strontium were determined for many feed ingredients, which provided substantial amount of new data currently unavailable in the literature.

  2. Abatement or ameliorative measures for adverse environmental impacts of aquaculture enterprises

    Chaluvadi, S; Ganapathy, Rrho ed; Kandan, Srho ed

    Proceedings of the Workshop on Environmental Impact Assessment of Aquaculture Enterprises, Chennai, December 10-12, 1997., Rajiv Gandhi Centre for Aquaculture, Subramaniyapuram (India), 1998, pp. 39-43

    Ameliorative measures to be taken for adverse environmental impacts of aquaculture are discussed. Major environmental impacts of aquaculture are (1) decrease in the regional ground water level, (2) sedimentation and destruction of coastal water flow, (3) discharge of aquaculture-effluents, and (4) chemical and human health hazards in general. The measures suggested to be taken to mitigate adverse environmental impacts are (1) a combined culture of fish and agricultural crops, (2) developing intensine farming, (3) planting mangroves and cultivation of seagrass, (4) planting of young trees, (5) avoid evaporatine and seapage losses of water and others. A note on waste treatment is also added.

  3. Current issues - Environmental impact assessment sustainable aquaculture development

    Krishnan, GS; Ganapathy, Rrho ed; Kandan, Srho ed

    Proceedings of the Workshop on Environmental Impact Assessment of Aquaculture Enterprises, Chennai, December 10-12, 1997., Rajiv Gandhi Centre for Aquaculture, Subramaniyapuram (India), 1998, pp. 171-179

    Environmental Impact Assessment (EIA) is important to develop environmentally acceptable aquaculture. MPEDA had initiated a study to know the interaction of the shrimp culture on environment and vise-versa. The aquaculture practices of several other nations were observed and blended with the locally available technology. This improved the technology in India. Effluents and their treatment systems are explained. Future strategies for aquaculture development are also discussed.

  4. Impacts of Trout Culture Effluent on Water Quality and Biotic Communities in Virginia Headwater Streams

    Selong, JH; Helfrich, LA

    Progressive Fish-Culturist [Prog. Fish-Cult.], vol. 60, no. 4, pp. 247-262, Oct 1998

    Five Virginia trout farms were selected for examination of effluent impacts on downstream water quality, periphyton production, and composition of macroinvertebrate and fish communities during fall 1994 and summer 1995. Annual trout production and feeding rates varied from 18.5 to 59.5 thousand kilograms and 15.6 to 87.6 thousand kilograms, respectively, and were correlated with discharge. Substrate embeddedness increased significantly (P < 0.07) downstream at two farms, but settleable solid concentrations in effluent were always less than 0.1 mL/L. Total ammonia nitrogen, un-ionized ammonia nitrogen, and nitrite nitrogen levels increased significantly (P < 0.001) downstream but were well below recommended thresholds for lethal exposure for aquatic organisms. Dissolved oxygen levels were significantly reduced (P < 0.001) downstream at postfeeding and predawn hours but were typically greater than 7.0 mg/L. Effluent water temperatures, pH, nitrate nitrogen, and total phosphorus concentrations did not differ from upstream levels. Settling ponds at two farms effectively reduced nutrient loadings downstream. Periphyton increased significantly (P < 0.001) downstream, but enrichment was localized to within 400 m. Macroinvertebrate richness and abundance of sensitive taxa (mayflies, stoneflies, and caddisflies) were reduced downstream, and pollution-tolerant noninsect taxa (isopods and gastropods) increased. Results of the U.S. Environmental Protection Agency's rapid bioassessment protocol (RBP), which integrates macroinvertebrate community metrics, reflected moderately impaired environmental conditions downstream at farms A and C and only slightly impaired or unimpaired water quality at the other farms. Results of the index of biotic integrity (IBI), which is based on fish community metrics, did not correspond with those of the RBP and reflected poor environmental conditions at farms C and D. Low fish species richness and abundance in these headwater streams limited the usefulness of the IBI for examining impacts of trout farm effluents.

  5. Empirical measurements of parameters critical to modelling benthic impacts of freshwater salmonid cage aquaculture

    Elberizon, IR; Kelly, LA*

    Aquaculture Research [Aquacult. Res.], vol. 29, no. 9, pp. 669-677, Sep 1998

    Although the waste dispersion models used in salmonid marine cage aquaculture could potentially be applied in freshwater cage aquaculture, much of relevant data on the waste particle parameters are unavailable. The present study provides new data on the wet densities of diets, the fall velocities of diets, the fall velocities of faecal matter and waste particle size. A significant increase of densities caused by the immersion time in water was observed. The wet density obtained from 60-s immersion time was found to be the effective settling density of diets. Fall velocities of salmonid diets were non-Stokesian and ranged from 0.02 to 0.12 m s super(-1) . These fall velocities did not significantly vary with water temperature. Fractionation of collected solid wastes from experimental tanks revealed that almost 60% by mass was retained on 2000-, 1000- and 500- mu m meshes. The fall velocities of these fractions were found to vary between 0.015 and 0.030 m s super(-1). The waste fraction that passed through a 500- mu m mesh had an estimated median diameter of 114.4 mu m. The observed fall velocities of both diets and solid wastes were lower than those commonly used in modelling waste dispersion in the marine environment. However, because of the relatively slow current velocities in most freshwater environments, it is expected that the wastes will tend to accumulate locally at cages.

  6. The Manzanar project: Towards a solution to poverty, hunger, environmental pollution, and global warming through sea water aquaculture and silviculture in deserts

    Sato, GH; Ghezae, T; Negassi, S

    In Vitro Cellular & Developmental Biology - Animal [In Vitro Cell. Dev. Biol. Anim.], vol. 34, no. 7, pp. 509-511, Aug 1998

    In recent memory, famine and poverty have plagued two countries with extensive coastal deserts - Eritrea (a former colony of Ethiopia) and Somalia. The premise of the Manzanar project is that such coastal deserts can be converted to rich agricultural fields through the culture of microscopic algae (blue-green bacteria) in seawater ponds, and the cultivation of mangrove species valuable for their timber through seawater irrigation.

  7. Describing benthic impacts of fish farming with fuzzy sets: theoretical background and analytic methods

    Angel, DL; Krost, P; Silvert, WL

    Journal of Applied Ichthyology [J. Appl. Ichthyol.], vol. 14, no. 1-2, pp. 1-8, Jul 1998

    Diver observations have been recorded over a period of several years at a site severely affected by finfish mariculture. The logged data were analysed using fuzzy logic in order to address the problem of interpreting sometimes qualitative and subjective information. The underlying methodology based on fuzzy set theory is developed and described in this paper, along with the techniques used to quantify the relationship between the information recorded by the divers, which was usually of a verbal descriptive nature, and a numerical index of benthic impact. Fuzzy logic proved to be a valuable tool for translating the dive log data into quantitative form.

  8. Impacts of aquaculture on the management of estuaries in India

    Bhatta, R; Bhat, M

    Environmental Conservation [Environ. Conserv.], vol. 25, no. 2, pp. 109-121, Jun 1998

    The emergence of commercial aquaculture in estuaries along the coast of Karnataka, India, has resulted in the breakdown of traditional methods of resource management and adverse impacts on the coastal environment. Based on field survey, personal discussions and published literature, we analyzed the evolution of different market (economic), traditional, and regulatory institutions governing the use of estuarine resources in the study area over the last three decades, and identified the environmental and social impacts of this evolution. In the past, informal associations of farmers in the estuarine floodplains had managed lands for raising crops and brackish-water fish in a sustainable way. In recent years, under economic and political pressures, landowners leased their lands to commercial shrimp-producers. A rapid growth in the production of commercial shrimp, employment of unsustainable production technologies, and laxity in environmental regulation have caused negative ecological and economic impacts on communities dependent on estuarine resources. Through a recent order from the Indian Supreme Court, environmentalists and the affected communities have sought to ban commercial aquaculture in ecologically-sensitive areas. While this court order awaits implementation, several policy options are here suggested for local, state and central governments in India in order to protect the estuarine environment.

  9. Nutritional Strategies For Reducing Pollutants in Aquaculture Effluents

    Ramseyer, LJ

    Dissertation Abstracts International Part B: Science and Engineering [Diss. Abst. Int. Pt. B - Sci. & Eng.], Apr 1998, vol. 58, no. 10, p. 4536

    A nutritional P mass balance model was constructed for coho and chinook salmon as a method of estimating P losses from the Platte River Anadromous State Fish Hatchery. For the production period of January 1993 through May 1994, the P mass balance model indicated that 37.7% of P fed was retained by fish, 21.0% was discharged in the feces, and 41.3% was discharged in dissolved form. Without any raceway solids removal, a maximum of 2.8 kg feed P super(.)metric ton [-1] fish produced was discharged into the hatchery's stabilization pond. This loss rate was the lowest reported for a salmonid hatchery. Efficient removal of raceway solids could have reduced hatchery P losses to 1.8 kg P super(.)metric ton [-1] fish produced. Improving the digestibility and utilization of nutrients in feeds should reduce nutrients in aquaculture waste water. Dietary phytate could impair dietary protein and mineral utilization in fish by binding zinc (Zn), creating a Zn deficiency. Zn deficiency could reduce protein and mineral utilization by reducing insulin secretion, insulin sensitivity, and the activity of the digestive enzymes carboxypeptidase B and alkaline phosphatase. Rainbow trout were fed diets containing untreated or dephytinized soybean meal and corn gluten meal with or without supplemental Zn to determine if fish dietary phytate impairs Zn bioavailability in fish.

  10. Use of macroalgae for treatment of fish farm effluents

    Kaas, R

    [Salt marshes and aquaculture: Sustainable activity for conservation and exploitation of coastal wetlands and salt marshes (symposium held in June 1996 and not in 1997)) MARAIS MARITIMES ET AQUACULTURE: ACTIVITE DURABLE POUR LA PRESERVATION ET L'EXPLOITATION DES ZONES HUMIDES LITTORALES (COLLOQUE TENU EN JUIN 1996 ET NON EN JUIN 1997), IFREMER, Plouzane (France), 1998, pp. 234-242, Actes Colloq. Ifremer, no. 19

    The use of algae in waste water treatments refers principally to integrated systems joining fish, shellfish and algae. Most works about this subject are driven in Israel, Canarian islands, Chile, Canada and Norway upon Ulva sp. and Gracilaria sp. We report about trials conducted in France on Gracilaria grown in oysterfarm effluents. In closed or semi closed systems, it appears that it is possible to control best flux rates, biomass, solar energy than in open system even if these are worth if considering the initial capital cost. Level of ammonia and light intensity are by and large most important. Amounts as high as 500 mmoles.m super(-2).d super(-1) can be removed with 90% of efficiency in optimal conditions. Consideration among the algae worth to use in water depuration must take in account the economical use of the produced biomass. Thus seaweeds of economical interest have to be prefered to the others when large cultivation have to be considered.

  11. Interactions between pollution and aquaculture in the Sado estuary, Portugal

    Vale, C; Gil Castro, O; Cortesao, C; Caetano, M

    [Salt marshes and aquaculture: Sustainable activity for conservation and exploitation of coastal wetlands and salt marshes (symposium held in June 1996 and not in 1997)) MARAIS MARITIMES ET AQUACULTURE: ACTIVITE DURABLE POUR LA PRESERVATION ET L'EXPLOITATION DES ZONES HUMIDES LITTORALES (COLLOQUE TENU EN JUIN 1996 ET NON EN JUIN 1997), IFREMER, Plouzane (France), 1998, pp. 70-76, Actes Colloq. Ifremer, no. 19

    Studies on the interactions between pollution and aquaculture are important in the Sado estuary because industries are located close to the salt marshes where most aquacultures are installed. In this paper we report the levels of PCBs and DDTs in fishes from the estuary and those collected in two extensive aquaculture tanks. Species from aquaculture contained less organochlorines than wild estuarine species, suggesting that aquaculture fishes are less exposed to PCBs and DDTs inputs. Oysters from natural grounds of the upper Sado estuary contain high concentrations of Zn, Cu and Cd. Crassostrea angulata was transplanted to a cleaner area (Ria Formosa) and the metal detoxification was surveyed. Levels of the three elements decreased at different rates, but concentrations increased sharply as response to redox changes near the sediment-water interface.

  12. Sanitary control of fish farms effluents in Atlantic salt marshes

    Le Bris, H; Pouliquen, H; Blanc, G

    [Salt marshes and aquaculture: Sustainable activity for conservation and exploitation of coastal wetlands and salt marshes (symposium held in June 1996 and not in 1997)) MARAIS MARITIMES ET AQUACULTURE: ACTIVITE DURABLE POUR LA PRESERVATION ET L'EXPLOITATION DES ZONES HUMIDES LITTORALES (COLLOQUE TENU EN JUIN 1996 ET NON EN JUIN 1997), IFREMER, Plouzane (France), 1998, pp. 204-212, Actes Colloq. Ifremer, no. 19

    The prospects of fish farming development in the Atlantic salt marshes has led the shellfish farmers to consider the eventual repercussions on the salubrity and health of cultured bivalves situated nearby the fish farms effluents. The National Veterinary School of Nantes has been managing experimental research programs in order to point out the potential influence of fish farms on shellfish cultures. This research concerns contaminations by coliform bacterias and chemotherapeutants used in fish farms. Some biological effects have been also tested (bacterial resistance to antibacterial agents, acetylcholinesterase activity inhibition...). These studies, in the limit of the methods used, showed that the repercussions seemed to be restricted to the immediate vicinity of the fish farms. Nevertheless, field approaches are needed to confirm these results obtained in experimental conditions.

  13. Biological treatment of intensive fish farm effluents using mass phytoplankton production

    Lefebvre, S; Hussenot, J

    [Salt marshes and aquaculture: Sustainable activity for conservation and exploitation of coastal wetlands and salt marshes (symposium held in June 1996 and not in 1997)) MARAIS MARITIMES ET AQUACULTURE: ACTIVITE DURABLE POUR LA PRESERVATION ET L'EXPLOITATION DES ZONES HUMIDES LITTORALES (COLLOQUE TENU EN JUIN 1996 ET NON EN JUIN 1997), IFREMER, Plouzane (France), 1998, pp. 224-233, Actes Colloq. Ifremer, no. 19

    The feasibility of using intensive fish-farm effluents (sea-bass, sea-bream) was evaluated as a source of inorganic nutrients for continuous mass production of marine diatoms. These experiments showed the high clearance efficiency of diatoms for inorganic matter (nitrogen, phosphorus). Moreover, appropriate silicate balancing was necessary with addition of liquid sodium silicate. The water replacement of on-growing fish ponds obliged to a continuous water treatment of effluents. Water treatment depends on severals factors. First, diatom growth rate is a function of temperature, light and nutrients. Second, the residence time in the reactor, which controls diatom growth rate, is conditionned by flow rate of effluents. Nutrient load of effluents depends on both fish biomass and growing conditions. A quantification essay was carried out using quantity of food pellets distributed to predict nutrient load of effluents. Management of added silicate and potential diatom production could be predicted too. In order to improve clearance efficiency, a bivalve integrated aquaculture system (oysters for example) could be designed as a microalgal biofilter.

  14. Biotreatment of fish farm effluents using the cyanobacterium Phormidium bohneri

    Dumas, A; Laliberte, G; Lessard, P; de la Nouee, J*

    Aquacultural Engineering [Aquacult. Eng.], vol. 17, no. 1, pp. 57-68, Feb 1998

    The potential environmental impact of effluent from fish farms is of increasing environmental concern. Although concentrations in total nitrogen and phosphorus are usually low, their impact on the environment cannot be ignored because of the high nutrient mass flows utilized during fish farming. In this paper we investigated the use of a non-toxic cyanobacterium, Phormidium bohneri, to remove dissolved inorganic nutrients from fish farm effluents. Wastewater was directed toward three completely mixed 70 1 photobioreactors with retention time of 8, 12 and 24 h, respectively. Average efficiencies of ammonia nitrogen removal from rainbow trout (Oncorhynchus mykiss) effluent was 82% and 85% for soluble orthophosphate, over a 1 month period. From these results, the potential use of P. bohneri as an alternative for the tertiary treatment of fish farm effluents is analyzed.

  15. Farming by the foot: How site-specific agriculture can reduce nonpoint source water pollution

    Kluge, JC

    Columbia Journal of Environmental Law [Columbia J. Environ. Law], vol. 23, no. 1, pp. 89-135, 1998

    This paper will first explain the nature of the nonpoint source pollution problem. Second, this paper will detail the current state of spatially variable technology and how it can reduce nonpoint source agricultural pollution. Lastly, this paper will argue for a national policy supporting the development of spatially variable agriculture with the goal of uniform mandated use of this technology within eleven years.

  16. The environmental impact of shrimp aquaculture and the coastal pollution in Mexico

    Paez-Osuna, F; Guerrero-Galvan, SR; Ruiz-Fernandez, AC

    Marine Pollution Bulletin [Mar. Pollut. Bull.], vol. 36, no. 1, pp. 65-75, Jan 1998

    The moderated, but continual development of the shrimp aquaculture in Mexico, in conjunction with municipal and agriculture effluents, in the last decade has created the first symptoms of negative environmental impacts, due mainly to the discharge of nutrients and organic matter into adjacent coastal waters. Similarly, the increasing impairment of coastal water quality resulting from the discharge of domestic, agricultural and industrial wastes into coastal waters has affected the aquaculture profitability in certain areas. The cumulative impact of the main anthropogenic sources of nutrients in the Mexican coastal states was estimated in 190 088 ton N yr super(-1) and 51 831 ton P yr super(-1). The input from shrimp aquaculture is only 1.5% and 0.9% of the main sources of nitrogen and phosphorus. This last input, though small, is related to local and adverse effects on coastal ecosystems. The introduction of management measures to mitigate the adverse environmental impacts of shrimp aquaculture development has now become necessary and urgent.

  17. Can nitrogen pollution from aquaculture be reduced?

    Kibria, G; Nugegoda, D; Fairclough, R; Lam, P

    Naga, vol. 21, no. 1, pp. 17-25, 1998

    Nitrogen is essential for the normal growth of fish. It is an important ingredient in fish feed but is very expensive. There is evidence that nitrogen loading from feeding and metabolic activities of fish can cause pollution of the receiving waters. This paper reviews nitrogen losses and nitrogen retention in fish and suggests ways of reducing nitrogen loading to the environment for a sustainable aquaculture program.

  18. Fake blue revolution: environmental and socio-economic impacts of shrimp culture in the coastal areas of Bangladesh

    Deb, AK

    Ocean & Coastal Management [Ocean Coast. Manage.], vol. 41, no. 1, pp. 63-88, 1998

    Shrimp culture in the coastal areas of Bangladesh rapidly expanded in the last two decades in an unplanned and unregulated way. To mirror the great complexity of impact of shrimp culture, both environmental and socio-economic issues have been examined. There is evidence that some of the impacts adversely affect the long-term sustainability of shrimp culture itself. The paper reveals the fact that if the societal value of the coastal environment that supports life-and-livelihood of millions of coastal communities of Bangladesh is not recognized, aquaculture industry might give rise to severe ecological, economic and social problems and conflicts. Some recommendations are made to improve the present situation and develop sustainable aquaculture.

  19. Towards reducing environmental impacts of pond aquaculture

    Boyd, CE; Massaut, L; Weddig, LJ

    INFOFISH Int., no. 2, pp. 27-33, 1998

    The rapid growth of aquaculture has been often cited as the cause of environmental damage in some areas. The negative impacts on the environment attributed to aquaculture are most often due to badly financed projects, inappropriate site selection and management procedures and lack of attention regarding the protection of the environment. Techniques for preventing and mitigating adverse impacts of pond aquaculture in various areas of environmental concern are discussed, considering the following: conversion of mangroves and other wetlands; eutrophication of natural waters; sedimentation in natural water bodies; salinisation of freshwater; use of chemicals; conversion of crop land to aquaculture ; excessive use of resources; and, negative effects on fisheries and biodiversity.

  20. Biological monitoring of organic pollution induced by marine abalone cage culture

    Ren, Yiping; Zeng, Xiaoqi

    Journal of Ocean University of Qingdao/Qingdao Haiyang Daxue Xuebao. Qingdao [J. Ocean Univ. Qingdao/Qingdao Haiyang Daxue Xuebao], vol. 28, no. 3, pp. 410-414, 1998

    From April to December 1991, benthic investigations were carried out in the abalone culture farm in Dalian Bay. The benthic community structures were analysed by using biological abundance, biomass comparison (ABC) and log-normal distribution of the individuals within a species (log-normal) methods. The organic pollution induced by the cage cultured abalones was monitored. The results show that the water was moderately polluted. The two biological monitoring methods are discussed.

  21. Brackishwater shrimp farming: Possible impacts on estuarine ecosystem

    Achuthankutty, CT; Sreepada, RA; Natarajan, Prho ed

    Advances in aquatic biology and fishereis: Prof. N. Balakrishnan Nair felicitation volume., University of Kerala, Kerala (India), 1998, pp. 175-189

    Aquaculture has been widely accepted as a practice that will supplement the capture fishery production, besides generating various types of job opportunities for the rural population. Coastal aquaculture has been given utmost priority in many developing and underdeveloped countries due to its potential for earning foreign exchange. However, aquatic systems have been under tremendous stress due to increased use to land and water resources, population growth and industrial development. Aquaculture as a user of water resources, may also be contributing to the stress and environmental imbalances if it is incorrectly conceived and/or operated. In India, shrimp aquaculture has developed as the largest aquaculture practice in within a decade. But, most the developments have been confined to the estuarine and brackishwater areas. Tropical estuaries being the most productive ecosystem and subjected to a variety of developmental activities, most of which bring in some environmental changes, it is important to look at the possible impacts the brackishwater shrimp aquaculture on the environment and the biota. In this paper, the improtant physical and biological processes influencing the estuarine ecosystem are briefly presented. The role of different types of flora and fauna (viz. phytoplankton, zooplankton, benthos, bacteria and fishes) in the estuarine productivity processes and their interdependence are highlighted. The importance of mangroves to the estuarine ecosystem in general and for the propagation of marine shrimps in particular is emphasisted. Status of brackishwater shrimp farming in India, possible impacts of coastal aquculture as a whole and shrimp aquaculture in particular on the ecosystem and dependant flora and fauna are described. Some areas which need special attention in making the brackishwater shrimp aquaculture into a sustainable and eco-friendly practice are listed.

  22. Inland water pollution and fish culture perspectives in Egypt

    Kenawy, SM; Hamza, AK

    Journal of aquatic sciences. Jos [J. Aquat. Sci.], vol. 13, pp. 55-58, 1998

    Inland waters in Egypt are subjected to continuous discharge of effluents from various origins. Consequently, degradation of the aquatic environment occurs leading to depletion in fish yield. Symptoms of pollution and its impact resulted from more than half billion cubic meters of effluents annually. This is explained in the present paper. Strict application of effective rules for environmental protection is called for, while more studies on the effects of pollution on fish culture need to be done. The use of sewage effluent in some fish culture projects in Egypt was tried out. The results seem to be promising though there are some scientific and socio-economical reservations.

  23. Regulating the local environmental impact of intensive marine fish farming I. The concept of the MOM system (modelling-ongrowing fish farms-monitoring)

    Ervik, A; Kupka Hansen, P; Aure, J; Stigebrandt, A; Johannessen, P; Jahnsen, T

    Aquaculture, vol. 158, no. 1-2, pp. 85-94, 1 Dec 1997

    The paper describes the concept of a management system called MOM (Modelling-Ongrowing fish farms-Monitoring) which may be used to adjust the local environmental impact of marine fish farms to the holding capacity of the sites. The concept is based on integrating the elements of environmental assessment, monitoring of impact and environmental quality standards (EQS) into one system. The amount of monitoring is dependent on the level of the environmental impact. Two terms are introduced: (1) the degree of exploitation, which is an expression of how much the site is being utilised, and (2) the level of monitoring, which determines the amount of monitoring depending on the environmental impact. For Norwegian conditions, a monitoring programme, including EQS, has been developed concerning the impact on the sediment under fish farms. It consists of three types of investigations of increasing elaboration and accuracy. A model, which simulates the environmental impact on a site given information about the farm's size and production and the hydrodynamic conditions and topography of the site, has been developed but not yet tested. The model and the monitoring programme with EQS are only briefly described, but will be published later. The MOM system should help to maintain satisfactory environmental conditions in and around fish farms and may be a valuable tool in site selection and coastal zone management.

  24. Impact of aquaculture effluents on mangroves

    Oswin, DS; Rahman, AA; Santhanam, R; Ramadhas, V; Gopalakrishnan, Prho eds

    Water quality issues in aquaculture. Proceedings of the National Seminar on Water Quality Issues in Aquaculture Systems, Dec. 18 and 19, 1996., Tamil Nadu Veterinary and Animal Sciences University, Tuticorin (India), 1997, pp. 15-22

    The present paper deals with the shrimp farm activities on the banks of the River Koraiyar at Muthupet, India. The effluent discharged from the shrimp farm and the management practices for effluent release during the tidal flushing have been characterized and discussed. The effluent canals should be planted with the wetland. Gravel beds and widening of canals which allow the reducing impacts from the shrimp farm provide strategies to abate pollution and eutrophication. The role of mangroves and other biological organisms on biofilteration is discussed in detail.

  25. Assessing benthic impacts of organic enrichment from marine aquaculture

    Hargrave, BT; Phillips, GA; Doucette, LI; White, MJ; Milligan, TG; Wildish, DJ; Cranston, RE

    Water, Air, & Soil Pollution Vol. 99, no. 1-4, pp. 641-650. Oct 1997

    Benthic observations were carded out at 22 stations in the Western Isles region of the Bay of Fundy on the east coast of Canada to evaluate impacts at salmon aquaculture sites. Eleven sites were located under salmon net-pens and 11 sites (reference or control locations) were at distances > 50 m from net-pens. Total S super(-) and redox potential (Eh) in surface sediment and benthic O sub(2) uptake and CO sub(2) release were sensitive indicators of benthic organic enrichment. High variability between replicate measurements of sediment gas exchange could reflect spatial patchiness in sedimentation of fecal waste and food pellets under fish pens. Biomass of deposit feeders was significantly increased at cage sites but total macrofauna biomass was similar at cage and reference locations. Surface sediment water content, modal grain size, pore water salinity and sulfate, and total biomass of macrofauna were the least sensitive indicators of enrichment.

  26. Socio-economic impacts of shrimp culture

    Primavera, JH

    Aquaculture Research [Aquacult. Res.], vol. 28, no. 10, pp. 815-827, Oct 1997

    Farmed shrimp contributed 27% of total world shrimp production in 1995 with a volume of 712 000 tonnes. Undoubtedly, the shrimp culture industry earns valuable foreign exchange for developing countries and generates jobs across the industry from fry gatherers to growers and processors. However, grave socio-economic consequences - including conversion, expropriation and privatization of mangroves and other lands; salinization of water and soil; decline in food security; marginalization of coastal communities, unemployment and urban migration; and social conflicts - have followed in the wake of, shrimp farm development in the Philippines and other tropical countries. The paper focuses on mangrove ecosystems: the valuation and cost-benefit analysis of their goods and services, and the mangrove-offshore fisheries connection. Research gaps in these areas and the need to internalize the ecological and socio-economic costs ('externalities') of shrimp farming are highlighted. Other recommendations include mangrove conservation and rehabilitation, enforcement of existing legislation, and introduction of environment-friendly aquaculture within the broader framework of community-based, integrated coastal area management, e.g. the traditional, extensive polyculture ponds in Indonesia.

  27. Impacts of harmful algae on the west-coast aquaculture industry and a national research plan by the Phycotoxins Working Group of Fisheries and Oceans to address such issues

    Whyte, JNC

    Bulletin of the Aquaculture Association of Canada., Sep 1997, pp. 19-25, Bull. Aquacult. Assoc. Can., no. 97-3

    Paralytic shellfish poisoning (PSP) and amnesia shellfish poisoning (ASP) are the main human health issues related to toxic algae on the west coast of Canada. Records of bivalve toxicity, resulting in closures of shellfish harvesting areas and adversely impacting the industry, show spatial, seasonal and yearly variance in toxic bloom events. Dense blooms of non-toxic algae such as Gonyaulax spinifera have caused death of bivalve molluscs from smothering and anoxia. Species of Dinophysis and Prorocentrum associated with diarrhetic shellfish poisoning (DSP) have not caused human illnesses on the Pacific coast. The economic impacts on the shellfish industry from harmful algae are related to costs associated with monitoring to protect public health, harvest closures when toxin levels exceed allowable levels, resultant shellfish mortalities, and reduced sales because of loss in consumer confidence. Toxic Heterosigma carterae is the major killer of farmed salmon, with cumulative losses in excess of $15 million. Physical obstruction of the gills of salmon from non-toxic diatoms Chaetoceros convolutus, C. concavicornis, Dictyocha speculum and Skeletonema costatum have caused death of fish from excess mucus formation and anoxia. Culture technologies are being developed that isolate fish from the effects of harmful algae; but such technologies are less practical for shellfish species. Priority areas of research are: phytoplankton monitoring of harmful algal blooms, uptake and depuration of biotoxins, harmful algal bloom dynamics, impacts and management approaches, and improved analytical methodology. This research can provide early warning of harmful bloom events and the protocols necessary to mitigate the adverse impacts harmful algae elicit on cultured fish and shellfish.

  28. Minimizing the environmental impact of land-based aquaculture

    Saroglia, M; Saroglia-Terova, G

    Report of the Symposium on Social, Economic and Management Aspects of Recreational Fisheries held in connection with the European Inland Fisheries Advisory Commission, nineteenth session, Dublin, Ireland, 11-19 June 1996 and reports of intersessional working parties' meetings. Rapport du Symposium sur les aspects sociaux et economiques et sur l'amenagement de la peche de loisir tenu a l'occasion de la dix-neuvieme session de la Commission europeenne consultative pour les peches dans les eaux interieures. Dublin, Irlande, 11-19 juin 1996 et rapports des reunions intersessions des groupes de travail, 1997, no. 541, suppl., p. 131, FAO Rapp. Peches

    Current research indicates that the main agents which may be the cause of environmental impacts originate from the feed delivered to fish, and are mainly constituted by nitrogenous metabolites, phosphates, suspended solids, BOD, low DO, rather than from drugs and antibiotics utilized either to prevent or treat diseases. During the past 20 years, mass balance studies for nutrients released from aquaculture have been reported in the literature by several scientists. The technical progress raised by aquaculture, when directed toward improving zootechnical performances and to reducing internal impacts, has also generally resulted in a reduction of environmental impact. The improvement of nutritional and oxygenation strategies with the adoption of high-energy extruded feeds and the use of liquid oxygen, were among the most revolutionary technologies, improving production results and reducing impacts as well. Moreover, the monitoring of recruited juveniles, adoption of well managed feeding strategies, computerized monitoring of water quality, development of specific vaccines, have also led to a reduction of the environmental impacts. Other aspects are also under investigation, such as the management of chlorophyll levels to control ammonia, the use of shape-focused models for monitoring and managing grow-out basins, controlling the biological cycle of parasites, the use of new vaccines and application routes, and alike, are all expected to reduce the potential environmental impact of aquaculture, whilst maintaining acceptable costs to the farmers.

  29. Aquaculture and the endogenous damage cost of water pollution: The case of Taiwan

    Huang, Chung-Huang

    Aquaculture Economics & Management [Aquacult. Econ. Manage.], vol. 1, no. 1, pp. 99-108, Mar 1997

    The endogenous damage cost of water pollution to eel production is derived based on a certainty equivalent model that takes into account a farmer's avoidance behaviour against water pollution, and differentiates the productivity effect of pollution control inputs from conventional productive inputs. Whether the marginal damage cost increases with pollution concentration depends on the difference between the direct damaging effect and the induced damage-reducing effect. A decreasing marginal damage cost curve of eel aquaculture in Taiwan is elicited, which explains partly the failure of a Coasian approach experimented in a recent conflict due to water pollution.

  30. Environmental impacts of aquaculture

    Stewart, JE

    World Aquaculture [World Aquacult.], vol. 28, no. 1, pp. 47-52, Mar 1997

    Aquaculture, as a commercial venture, is now being pursued in areas where it did not exist previously and has become a significant competitor for space in the coastal zone and freshwater areas. A wide variety of species, both plants and animals, are cultured world-wide. The latest available statistics show the total production for 1993 as 22 540 451 tonnes or between 20 and 25% of the food harvested from the sea and freshwater areas. The quantity for inland culture was 10 725 832 tonnes of which carp, barbels and other cyprinids comprised the greatest volume (7 638 001 tonnes); marine culture of fish and shellfish equalled 5 559 303 tonnes to which must be added 6 255 316 tonnes for aquatic plants and 84 674 tonnes of others for a total of 11 899 293 tonnes produced by marine culture. Species grown in quantity in marine areas, in addition to seaweeds, include the pearl oyster, edible oysters, abalone, mussels, scallops, prawns, milkfish, Atlantic salmon, yellowtail, rainbow trout and sea bream. Other species, such as halibut and Arctic char, are in the commercial development phase. For aquaculture to be accepted it must demonstrate convincingly that aquaculture activities will not jeopardize other legitimate uses of the coastal, brackish and freshwater areas by causing unacceptable changes in environmental quality. To be able to offer such assurances, methodology must be developed that will permit authorities to assess the consequences of various loadings. Unfortunately, we do not have a model that will allow us to estimate the limits to the assimilative capacity of the various culture locations or the full consequences of exceeding these limits. Studies undertaken over the past decade to fill this gap have resulted in a variety of hydrographic and other numerical models. They do not, however, possess a biological component to illustrate the consequences for the ecosystem in general or the organisms being cultured.

  31. Reducing the environmental impact of high density fish production: An integrated approach to solids treatment for recirculating aquaculture systems using expandable granular biofilters

    Golz, W; Malone, RF; Chen, Shulin

    INTERACTIONS BETWEEN CULTURED SPECIES AND NATURALLY OCCURRING SPECIES IN THE ENVIRONMENT., Jan 1997, pp. 157-164, UNJR TECH. REP., no. 24

    Over the past decade, regulatory agencies have begun to view the environmental impact of wastes discharged from high density flow-through fish production systems with increasing concern. At the same time, recirculating aquaculture systems have gained wider acceptance because of their ability to reduce waste discharges, improve quality control and reduce costs. The crucial processes that must be addressed in treating recirculating water are solids capture, biofiltration, aeration, degasification and ion balance. Designs that integrate two or more of these processes provide the greatest potential for cost reduction. The technology that is the focus of this paper is an expandable granular biofilter (EGB), which integrates solids capture and biofiltration in a single unit process. Backwash frequency is a major operational parameter of EGBs, influencing the volume of sludge produced and the nitrification rate. Computer and mass balance models are used to describe the relationship between solids residence time, sludge production and nitrification rates. The models show that infrequent backflushing decreases water loss and sludge production, although nitrification rates decline for extended solids residence times. Declining nitrification rates reflect decay of the accreting solids mass - which creates an internal ammonia and BOD load, decreasing the oxygen available to the nitrifiers because of heterotrophic competition for oxygen and impeded mass transfer as the bed becomes occluded. Nitrification appears to be optimized with solids residence time in the range of 2-3 days, for filters utilized as the primary solids capture device. The focus of this paper is: (1) primary in-filter solids stabilization; (2) the effect of in-filter solids stabilization on nitrification; and (3) post-discharge, pre-disposal digestion of aquacultural solids.

  32. Water conservation and pollution control for intensive prawn farms

    Chin, KK; Ong, SL

    WATER QUALITY AND POLLUTION CONTROL IN ASIA., 1997, pp. 77-81, Water Science and Technology, vol. 35, no. 8

    Hundreds of fish and prawn farms (Penaeus monodon), (Penaeus indicus) were constructed in the past decades. Many of these farms have ceased operation mainly due to the outbreak of diseases. With population increase, rapid urbanization and industrialization, water quality at the estuary and coastal regions where most of the fish and prawn farms are located is deteriorating. Treatment and recycling of water are essential to maintain the water quality at an acceptable level. A system consisting of preliminary settling, biofiltration, secondary settling and final polishing with a biofilter was tested in an experimental farm. Water quality was maintained at relatively good level at the cultivating pond after 120-day growing period. The growing facilities continued to show good performances after 4 growing cycles with a 2-week rest period between each cycle. Similar system was installed at a 26-hectare farm site having several ponds with sizes varying from 0.7 to 2.5 hectares. No disease outbreak was encountered after the installation of the treatment and recycling facilities.

  33. Impacts of fish farming on the state of Estonian coastal sea

    Herman, A

    Eesti Tead. Akad. Toim. (Biol. Oekol.)/Proc. Est. Acad. Sci. (Biol. Ecol.), vol. 46, no. 3, pp. 164-173, 1997

    To assess and predict the impacts of fish farms on marine environment, a joint research project was launched in 1987 by the Nordic Council of Ministers. The state of marine environments is affected by the discharge of nutrients and suspended matter, both organic substances and chemical compounds, into the sea from fish farms. However, fish farms are by no means the greatest sources of sea pollution. In 1994-95 fish farms were responsible for less than 1% of both N and P load in the Baltic Sea. To further decrease the load of pollution in the Baltic Sea fish farming should be developed in harmony with the environment. This calls for the use of environmentally friendly feeds and materials at the marine fish farms, improved feeding methods ensuring efficient utilization of nutrients, and the location of the farms in areas with an appropriate hydrological regime.

  34. Immunoindicators of environmental pollution/stress and of disease outbreak in aquaculture

    Dinakaran Michael, R

    Developing and sustaining world fisheries resources. The state of science and management., CSIRO, Collingwood (Australia), 1997, pp. 514-519

    The objectives of this paper were to present the immunotoxic effect of some of the aquatic pollutants (heavy metals and pesticides) on the immunity in the tilapia (Oreochromis mossambicus) and to develop a model for using the possible immunomodulatory effect of these pollutants as an indicator of environmental pollution/stress for predicting microbial infection and the consequent disease outbreak in aquaculture. When groups of 0. mossambicus were exposed to very small concentrations (0.1-10% of the LD/LC sub(50) concentrations) of heavy metals such as chromium, mercury, nickel, lead or aluminium and pesticides such as Monocrotophos, Endosulfan or Quinoiphos, there was significant reduction in the magnitude of antibody response and the number of leucocytes/lymphocytes. In the field test, when fish were maintained in cages in polluted waters, the magnitude of immune response was reduced. There is a broad spectrum of immunological assays which can be used for indicating environmental pollution/stress. If these tests indicate that the immune system of the fish is compromised, microbial disease outbreak can be predicted and steps can be taken to save the fish.

  35. Pollution and degradation of African aquatic environments and consequences for inland fisheries and aquaculture: The case of the republic of Zaire

    Mino-Kahozi, K; Mbantshi, M

    African Inland Fisheries, Aquaculture and the Environment, Fishing News Books, 1997, pp. 99-114

    Humans depend on their surrounding physical environment for the resources they need for their survival. However, human exploitation of these resources causes environmental degradation. There is therefore a clear duality between exploitation and conservation. Human activities have a tendency to degrade rather than to conserve. Moreover, curative measures prove to be more costly than preventive measures; hence the need for ongoing monitoring of the environment to maintain the ecological balance of ecosystems. Zaire is well endowed with freshwater reserves, which represent a vital resource for a variety of human activities, such as agriculture, fisheries, industry and domestic use, and provide a living environment for an array of aquatic organisms. However, a large number of users of Zairian resources still adopt behaviour patterns that degrade and pollute aquatic environments.

  36. A veterinary approach to the study of environmental impact caused by aquaculture

    Ioppolo, A; Vischetti, M; Melchiorre, S; Cappella, MG; Volterra, L; Mancini, L

    Riv. Ital. Acquacolt., vol. 32, no. 3, pp. 89-95, 1997

    In accordance with EC directive 337/85, this work aims at improving knowledge of water quality, based on physical, chemical, microbiological and biological data, by searching for macro-invertebrates in a biological map of watercourses. Such data are useful to veterinarians aiming at using new methods to check environmental alterations by calculating the extent of reduced biodiversity according to decreases in the numbers of the most sensitive species present in the community in question.

  37. Pollution from fish farms: Methods applied and evaluation of results

    Ioppolo, A; Vischetti, M; Melchiorre, S; Cappella, MG; Volterra, L; Mancini, L

    Riv. Ital. Acquacolt., vol. 32, no. 3, pp. 97-104, 1997

    A pilot study was carried out on the upper course of a river in Central Italy in which several fish farms are located. In one of these, a monitoring plan was implemented, to highlight biological quality by means of study of benthic macro-invertebrates using the Extended Biotic Index (E.B.I.), together with chemico-physical and microbiological analyses of incoming and discharged waters. This research took place between 1991 and 1995, so that possible variations in the quality of the body of water in question could be checked over a period of several years. Results show that intensive fish farming causes changes in aquatic environments subjected to constant uptake and discharge of waters, due to increases in organic matter and toxic substances and the addition of the chemotherapeutic drugs used in intensive farming. Deterioration in water quality was also confirmed by the results of microbiological, chemico-physical and biological analyses.

  38. Environmental impact on the development of agricultural technology in China: The case of the dike-pond ('jitang') system of integrated agriculture-aquaculture in the Zhujiang Delta of China

    Lo, CP

    Agriculture, Ecosystems & Environment [Agric. Ecosyst. Environ.], vol. 60, no. 2-3, pp. 183-195, Dec 1996

    The development of the environmentally conserving dike-pond system of integrated agriculture and aquaculture in the Zhujiang Delta of south China is traced to illustrate the impact of environmental changes on technological innovations. The technologies of dike building, land reclamation, pond fish culture, and crop cultivation on dikes, which were either independently developed or modified from ideas brought in by migrant farmers from northern China, represented farmers' efforts to adapt to the new characteristics of a changed environment as population pressure increased. The new technologies revealed the farmers' awareness of the need for environmental conservation. However, increased population pressure also necessitated more intensive use of the land, both in the highland and lowland regions, giving rise to inappropriate dike building and premature reclamation activities, which in turn brought about more frequent flooding in the delta region. Careless application of a new technology tended to have harmful effects on the environment. Political conditions in different periods of China's economic development have also caused changes in the dike-pond system which has to maintain high productivity and profitability. Recent advances in dike-pond system technology have focused on crop diversification and animal husbandry to match the three-dimensional characteristics of its ecological components. New agricultural technologies can be successful in China only if they can provide a balance between land use and conservation.

  39. Issues, impacts, and implications of shrimp aquaculture in Thailand

    Dierberg, FE; Kiattisimkul, W

    Environmental Management [ENVIRON. MANAGE.], vol. 20, no. 5, pp. 649-666, Oct 1996

    Water quality impacts to and from intensive shrimp (Penaeus morodon) aquaculture in Thailand are substantial. Besides the surface and subsurface salinization of freshwaters, loadings of solids, oxygen-consuming organic matter, and nutrients to receiving waters are considerable when the cumulative impacts from water exchange during the growout cycle, pond drainage during harvesting, and illegal pond sediment disposal are taken into account. Although just beginning to be considered in Thailand, partial recirculating and integrated intensive farming systems are producing promising, if somewhat limited, results. By providing on-site treatment of the effluent from the shrimp growout ponds, there is less reliance on using outside water supplies, believed to be the source of the contamination. As integrated aquaculture management becomes more the practice than the exception, less risk of crop failure to the industry and reduced discharge loadings from intensively managed shrimp ponds to receiving waters can be expected. Projected limitations on growing and marketing shrimp in the future, such as scarcity of land and broodstock, continued disease outbreaks, negative publicity, regulatory enforcement, water treatment and solids disposal costs, and increased competition from growers in other Asian countries will also drive the government and the industry towards adopting integrated aquaculture management.

  40. Aspects of phosphorus pollution from aquaculture

    Kibria, G; Nugegoda, D; Lam, P; Fairclough, R

    Naga. Manila [Naga], vol. 19, no. 3, pp. 20-24, Jul 1996

    Phosphorus is an essential element for living organisms and exists in waterbodies as dissolved and particulate forms. Phosphorus is required for optimum growth, feed efficiency, bone development and maintenance of acid-base regulation in fish. The presence of high concentration of phosphates in water may indicate presence of pollution as it may accelerate plant growth and disrupt the aquatic ecosystem thereby benefiting certain species and altering species diversity in affected areas. Eutrophication of waterbodies is often correlated with the phosphorus loading into the environment and aquaculture has been identified as one of the sources of phosphorus pollution. Details of the impacts of eutrophication is given in Bernhardt (1981). Phosphorus must be provided in fish feed because of its low concentration in water. Studies made in Europe and Northern America have revealed a phosphorus surplus in most commercial feeds which is above actual requirements; or is supplied in a form which is unavailable to the fish. Surplus phosphorus is excreted, while unavailable phosphorus is passed out in the feces. Discharge of phosphorus from fish farms and hatchery effluents have caused phosphorus pollution in Nordic countries, North America and Europe. This article examines the path of phosphorus pollution, quantification/prediction of phosphorus load from aquaculture and remedial measures.

  41. "Scoping" the potential social impacts of open ocean aquaculture

    Robertson, RA; Lindsay, BE; Gardoqui, DM

    OPEN OCEAN AQUACULTURE. PROCEEDINGS OF AN INTERNATIONAL CONFERENCE, MAY 9-10, 1996, PORTLAND, MAINE., 1996, pp. 337-352

    Open ocean aquaculture offers the potential for regional economic development, improving the balance of trade, new employment opportunities, and the replenishment of wild stocks of commercially and recreationally important aquatic species (Royal, 1993). In addition, the ability to monitor the products from aquaculture for compliance with official inspection standards and the short time interval between harvest and slaughter, make cultured products safe and dependable. The production aspects also allow for a reliable harvest of uniform size and weight, devoid of seasonal fluctuations, appealing to both distributors and retailers (Lovell, 1991). The realization of these potential benefits combined with declining stocks for capture fisheries serves to stress the importance of the development of a finfish aquaculture industry in Northern New England.

  42. Environmental impacts of coastal aquaculture development

    Pillai, VK; Narasimham, KA

    Marine biodiversity conservation and management, Central Marine Fisheries Research Institute, Cochin (India), 1996, pp. 152-160

    Management measures to mitigate deteriorating water quality and the adverse environmental impacts of aquaculture development are to be dealt with as a priority area and a holistic approach is needed. Environmental baseline studies are necessary to establish and assess environmental quality and to be able to quantify in economic terms.

  43. Social and environmental impacts of coastal aquaculture in Indonesia

    Muluk, C; Bailey, C

    AQUACULTURAL DEVELOPMENT: SOCIAL DIMENSIONS OF AN EMERGING INDUSTRY., WESTVIEW PRESS, INC., BOULDER, CO (USA), 1996, pp. 193-210

    Shrimp production has been practiced in Indonesia for hundreds of years in brackish water coastal ponds, locally known as tambak. Historically, shrimp has been raised along with milkfish (Chanos chanos, Forsk.) using minimal inputs. Recently, however, international demand for shrimp, government policies to expand foreign exchange earnings, and technological advances in the production system have transformed coastal aquaculture from a small-scale enterprise geared towards production of fish and shrimp for domestic markets to more capital-intensive shrimp mariculture systems oriented towards export markets. Small-scale farmers gradually are being displaced by urban entrepreneurs who purchase or lease ponds for intensive shrimp production, or by local elites who are expanding their control over productive lands, but who continue to use low-input shrimp cultivation technologies.

  44. Pollution control for aquaculture

    Midlen, A

    CHAPMAN & HALL, LONDON (UK), 1996, 256 pp

    This book aims to bring the principles of wastewater treatment and other pollution control techniques for fish and shellfish farming to a wide audience of farmers, students, scientists, engineers - in fact anyone with an interest in aquaculture or pollution control. The text is written with both the specialist and those new to the subject in mind.

  45. Intensive fish cage farming -- impacts, resource demands and increased sustainability through integration

    Troell, M

    SU, STOCKHOLM (SWEDEN), 1996, 29 pp

    The rapid development of intensive aquaculture has been followed by impacts on the environment. The unsustainable characteristics of the present development were analysed from a large-scale ecological-economical perspective with examples from both tropical and temperate regions. Comparison of cage farming revealed that similar eutrophication effects occurred in Lake Kariba, Zimbabwe as in temperate regions but indicated that tropical systems more efficiently could process depositions of wastes. Intensive cage farming was shown to require a larger input of external resources than pond farming and was thus dependent of a larger support area. By applying the "pollutor pays" principle, environmental costs of eutrophication in Swedish salmon (Salmo salar) cage farming was internalized. Costs for reduction of nutrients in a 100 ton farm were shown to correspond to a 16-38% tax of total costs. A comparison between open sea monoculture farming and an integrated recycling-based culturing revealed that integrated systems resemble natural ecosystems implying reduced costs and environmental impact. Filtration by mussels integrated with cage farming was not highly efficient to reduce loads to the environment but promising results were achieved in co-cultivation of the seaweed Graciliana chilensis which was able to remove 50% of dissolved ammonium in winter and 90-95% in spring.

  46. Modelling environmental impacts of marine finfish aquaculture

    Silvert, W; Sowles, JW

    Journal of applied ichthyology/Zeitschrift fur angewandte Ichthyologie. Hamburg, Berlin [J. APPL. ICHTHYOL./Z. ANGEW. ICHTHYOL.], vol. 12, no. 2, pp. 75-81, 1996

    Our understanding of the interactions between fish farms and the environment has reached the stage where it is reasonable to expect that quantitative estimates of the possible environmental consequences of aquaculture development can be provided for regulatory and mitigation purposes. This paper summarizes recent developments in this area and provides several case histories of areas where theoretical analyses appear to have direct practical relevance.

  47. Environmental Impact Assessment (EIA) studies in floating cage culture systems in Greece

    Klaoudatos, SD; Conides, AJ; Chatziefstathiou, MV

    PARTNERSHIP IN COASTAL ZONE MANAGEMENT., SAMARA PUBLISHING LTD., CARDIGAN (UK), 1996, pp. 525-532

    Intensive aquaculture in Greece today is applied mainly through the installation and use of floating net cages located nearshore. This has led to numerous conflicts between aquaculture activities and the local environment as represented by tourism, industry and urban development. Recent international experience has shown that all waterfront activities may substantially affect the coastal environment by releasing effluents to the environment. It is also known that these effluents differ significantly regarding the amount disposed and in chemical composition. As the cultivation of marine organisms is completed in the water environment, it is impossible to control effluents before entering the environment. This study examines the environmental impact of a sea bass floating cage fish farm in Greece based on the following axes: the theoretical output as it can be estimated and quantified according to energy budget models; the collection and chemical analysis of the particulate part of the effluent using a specially constructed collector and nutrient analysis of the seawater. According to the results of this study, it was found that the levels of pollution from the studied 200 tn-cage fish farm are very low and found: proteins 6.811 kg/day, lipids 0.357 kg/day, carbohydrates 6.483 kg /day and particulate matter (ash) 9.309 kg/day.

  48. Some practical ways to reduce the environmental impacts of marine fish farming

    Wu, RSS

    PROCEEDINGS OF THE PACON CONFERENCE ON SUSTAINABLE AQUACULTURE '95., 1996, p. 441

    The recent dramatic growth of marine fish culture in many countries has raised considerable environmental concern. The high organic and nutrient loadings generated by marine fish culture have caused localized pollution problems in coastal environments. Environmental impact can be significantly reduced by keeping the stocking density under the carrying capacity of water body in which fish is cultured. An example on the use of computer simulation model to estimate the carrying capacity of water and maximum stocking density is demonstrated. The high organic and nutrient loadings can be successfully harvested by integrated culture with macroalgae (Ulva lactuca), filter feeders (oysters and mussels) and deposit feeders (sea cucumbers). Feed wastage and pollution loading can be significantly reduced by manipulating composition of feed and improved feed technology. Environmental impact assessment should be carried out prior to fish farming. Various successful examples in reducing pollution impacts of marine fish farming will be discussed.

  49. Aquaculture pollution -- a fallacy

    Jerald, IJA

    FISH. CHIMES, vol. 16, no. 3, pp. 19-20, 1996

    The author has the opinion that majority of the aquaculture practices have had little or no effect adverse impact on the ecosystem. According to him aquacultre is a self purifying industry and it is a fallacy to say that aquaculture caused pollution.

  50. Aspects of phosporus pollution from aquaculture

    Kibria, G; Nugegoda, D; Lam, P; Fairclough, R

    Naga. Manila [NAGA], vol. 19, no. 3, pp. 20-24, 1996

    This article examines the path of phosphorus pollution, quantification /prediction of phosphorus load from aquaculture and remedial measures.

  51. Fish farming and environmental impact

    Ballestrazzi, RGU

    Laguna, no. 4, pp. 6-13, 1996

    Intensive fish-farming involves the discharge of fluid waste which may threaten water quality; the use of new types of nutrition, management and equipment allows a reduction of such negative effects.

  52. Environmental impacts of nutrients from aquaculture: Towards the evolution of sustainable aquaculture systems

    Costa-Pierce, BA

    AQUACULTURE AND WATER RESOURCE MANAGEMENT., BLACKWELL SCIENCE, 1996, pp. 81-113

    Scientific interest in the impacts of nutrient pollution from aquaculture has increased markedly since the 1980s (Rosenthal et al. 1987; ICES 1989; Institute of Aquaculture [IOA] et al. 1990; Cowey & Cho 1991; DePauw & Joyce 1991; Iwama 1991; Maekinen 1991; Pullin et al. 1993), and especially so in the past 10 years as aquaculture has become one of the world's fastest growing agriculture industries (Davlin 1991). Concerns about aquaculture pollution, combined with real and perceived water quality degradation, health concerns, and other violations of the public trust, have fuelled vigorous public and policy debates. Controversies have resulted in adoption of regulations intended to preserve the integrity of natural ecosystems and to ameliorate the public's concerns. The increasing regulatory burden has been cited as one of the main factors slowing the growth of aquaculture (Axler et al. 1994). The political strength of international and grass roots environmental organisations, combined with the ascent to power of a post-World War II generation acutely aware of the potential environmental impacts of food-producing industries have dramatically changed environmental policies world-wide. Regulations have been promulgated to address new concerns about the preservation, sustainability and stewardship of the environment. As a result, the water pollution control agenda has shifted from a 'user pays' to a 'preservationist' stance that opposes addition of any new sources of aquatic pollution, combined with a switch in management philosophy to adoption of sustainability, and integrated and ecosystems criteria. Holistic water systems management, and watershed-level planning processes have become modern dogma in the attempt to manage natural environments better. However, the methods needed for such ecosystem level approaches remain poorly developed.

  53. A global experiment on tilapia aquaculture: impacts of the Pond Dynamics/Aquaculture CRSP in Rwanda, Honduras, the Philippines and Thailand

    Molnar, JJ; Hanson, TR; Lovshin, LL; Circa, AV

    Naga, vol. 19, no. 2, pp. 12-17, 1996

    The Pond Dynamics/Aquaculture Collaborative Research Support Program (PDA/CRSP) is a global research network to generate basic science that may be used to advance aquaculture development. One of a family of research programs funded by the United States Agency for International Development (USAID), the CRSP focuses on improving the efficiency of aquaculture systems. The PDA/CRSP began work in 1982 in Thailand, and subsequently in the Philippines, Honduras, the US and, until recently, Rwanda. At all the sites, the goal is the same: to identify constraints to aquaculture production, and to design responses that are environmentally and culturally appropriate. The research network's global experiment has focused on tilapia (Oreochromis niloticus), although some sites have devoted attention to marine shrimp and other locally significant species. Impact of the network's investigations with tilapia is examined in this article.

  54. Environmental impacts of salmonid culture

    Weston, DP; Phillips, MJ; Kelly, LA

    Principles of Salmonid Culture, Elsevier, 1996, pp. 919-968, Developments in Aquaculture and Fisheries Science , vol. 29

    Until very recently most research relating environmental quality and aquaculture was limited to assessment of environmental conditions necessary for culture. Emphasis was placed on dissolved oxygen requirements of the cultured fish or the maximum dissolved nitrogen levels that could be tolerated without impairment of growth rates or survival. Most attention was directed towards the effect of the environment upon the aquaculture operation, while the converse perspective, the effect of aquaculture upon environmental quality, was largely ignored. The possibility that aquaculture itself could degrade water quality with adverse effects upon native flora and fauna received increasing attention in the 1970s with several investigations of environmental conditions downstream of land-based culture operations.