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<i>Vegetarian Journal</i> Cover


Vegetarian Journal

Excerpts

Jul/Aug 1997

Volume XVI, Number 4




Acquaculture: An Overview

Part II, By Jeanne-Marie Bartas


Summary of Part I

In Part I of this two-part article (Vegetarian Journal, May/June 1997 issue), we looked at several aspects of aquaculture, including the industry's management of its source and quality of water and feeds, and scientific research in aquaculture. In this part, we will examine regulatory issues and the environmental impacts of aquaculture. We will then briefly suggest what the future of aquaculture will be and close with the author's analysis and commentary.

Regulation of Aquaculture

Aquaculture is regulated on both the state and federal levels. All aspects of fish farming, including fish rearing, harvesting (of wild-caught fish), medication, processing, and selling are regulated, although certain aspects are more regulated than others. The regulatory agencies include the Food and Drug Administration (FDA), the Environmental Protection Agency (EPA), the Department of Agriculture, and the Department of Health and Human Services. In the interest of space, we will restrict our discussion to the regulation of therapeutants (commonly known as drugs), and the regulation of the effluent (liquid waste water) and solid waste produced by the industry.

The topic of drug regulation should be of great concern to those who consume fish, because the health risks associated with drug residues in seafood are largely unknown. The concern is heightened by the fact that most of the seafood eaten by Americans is from foreign sources. Since the regulation of seafood safety and the number of permitted drugs in aquaculture varies from country to country, the consumer of seafood may be taking a risk of which he or she may not even be aware.

The topic of effluent and solid waste regulation in aquaculture is of interest to everyone, in that these wastes impact our common environment, especially our water and land. As regard for the environment is becoming more and more important to many people, it will be informative to look at how our government regulates aquaculture's waste products.

Drugs

There are five FDA-approved drugs for use in food fish in the U.S., compared with fifteen in Europe and twenty-four in Japan.1 These are Terramycin (oxytetracycline), Romet 30(orometopum sulfadimethoxine), Finquel (tricaine methanesulfonate, or MS-222), formalin, and sulfamerazine. Finquel is an anesthetic. Formalin is a parasiticide (a substance which kills disease-causing agents known as parasites), and the remaining three are antibiotics.2 Sulfamerazine is no longer manufactured because fish culturists purchased the cheaper generic or nonfish versions of the drug.3 Each drug is approved only for specific species of fish. They can be legally used only in those species, at the listed dosages, and when certain disease conditions are present.

There are so few drugs because pharmaceutical companies are often hesitant to invest millions in order to test a drug to be used in a relatively small industry such as the aquaculture industry. The testing is necessary, however, according to a 1991 National Academy of Sciences document in which it was concluded that chemicals are not effectively controlled in aquaculture.4 Because of the lack of control, the NAS recommended that additional studies be completed on contaminant risks, and that all imported seafood must meet U.S. standards of safety. This matter is complicated by the fact that many more drugs are approved for use in aquaculture in other countries, such as Japan and those in the European Economic Community, which export a large percent of aquacultural products consumed in the U.S. Other problems are created as regulations and laws differ from country to country.

The Center for Veterinary Medicine (CVM) at the FDA is responsible for reviewing and approving drugs for use in animals. Its primary enforcement priority has been concerned with drug manufacturers and distributors. Its secondary priority is concerned with medicated feed manufacturers. CVM, through these regulatory strategies, aims to permit only approved drugs to be in circulation and at the recommended dosage levels. CVM does not do routine inspections for enforcement purposes. They do conduct "for cause" inspections (in situations where the CVM has reason to believe that questionable practices exist) and surveillances of drug investigators using drugs under the investigational exemption status.5

Investigational New Animal Drug Exemptions. (INAD exemptions) permit the testing of various types of drugs including antibiotics, general antimicrobials (used to combat disease-causing agents), parasiticides (used to kill parasites), anesthetics, and spawning aids (used to induce egg-laying). CVM reviews the applications for this exemption and gives limited permission for its use. According to Tom Bell of the FDA's Division of Therapeutic Drugs for Animals, "INAD exemptions permit the otherwise illegal use of an unapproved drug in studies designed to generate data required by CVM to approve the drug."6

Previously, INAD exemption permits were occasionally issued for "compassionate use." For example, the FDA recognized that at one time little or no data were being generated on some compounds (such as erythromycin) under INADs even though such data generation was required by law.7 Sometimes, the situation is further complicated by the fact that if the FDA revises its INAD procedures, the FDA may reverse its decision concerning a drug which once had INAD status. Such is the case of the drug, malachite green. Upon re-evaluation, the FDA concluded that insufficient evidence existed for its safe, experimental use.8

According to the FDA's Tom Bell, "Before a drug can be approved for use in fish ..., data must be submitted to CVM. The data must demonstrate that the drug is safe and effective. These requisite data are produced under both laboratory and productional settings. Fish tested under production settings may be authorized by CVM, in some cases, to be either harvested for human consumption or released into public waters. Harvest or release, authorization will only be provided if sufficient information has been provided to CVM from which to set a safe investigational withdrawal period (minimum time from last drug exposure to harvesting, during which the drug is depleted from edible tissues)."9 The data are intended to protect the health of those consuming the previously exposed fish.

CVM has the authority to exercise discretion in deciding when to enforce the law. So, for instance, the CVM "permits" the use of "low regulatory priority drugs" such as salt and ice. These substances pose minor (if any) safety concerns when used under specific conditions according to CVM. FDA approval is not required for these drugs.10

This brief overview of drug regulation in aquaculture should give the seafood consumer cause for concern. Many drugs used in farmed fish from other countries have not been approved by the FDA. These fish are eaten in the United States even though health risks associated with the drugs are not known. Furthermore, fish which have been given experimental drugs in this country may be sold on the market or released into public waters. The possible health and environmental risks are not known. Considering the potentially negative health and environmental effects, the reader may rightly question if drug use in aquaculture is adequately controlled.

Effluent and Solid Waste

The EPA is primarily responsible for the regulation of effluent (discharged waste water) and solid waste produced by aquaculture. Some aquacultural facilities are required to apply for a National Pollution Discharge Elimination Systems (NPDES) permit if their waste production is of a certain type and quantity.

According to the regulation, "concentrated aquatic animal production facilities" are point sources of pollutants (i.e., identifiable sources of pollution), and as such they require NPDES permits for discharges into U.S. waters.11 These facilities include hatcheries, fish farms, or other facilities that contain, grow, or hold aquatic animals. Facilities are divided into three categories: (1) those which produce cold water species; (2) those which produce warm water species; (3) any other facility deemed by the EPA Director to be a significant contributor of pollution to U.S. waters.

There are exemptions to the first and second categories. Those facilities producing cold water species such as trout or salmon are exempt if they: 1) produce less than approximately 20,000 pounds of animals per year, or 2) feed less than 5,000 pounds of feed during the calendar month of maximum feeding. All other facilities which discharge at least thirty days per year must have a NPDES permit.12

Secondly, those facilities producing warm water species such As catfish or minnows are exempt if they discharge only during periods of excess runoff. Also exempt in this category are facilities which produce less than 100,000 pounds of animals per year. All other facilities which discharge at least thirty days per year must have a NPDES permit.13 Aquaculture practiced in the tidal waters of Maine is exempt from the NPDES program.14

It is believed that these minimum standards set by the EPA will require that most commercial cold water aquaculture facilities obtain NPDES permits. Most warm water facilities, however, may be managed so as not to require NPDES permits. Exemption from the NPDES permit program could be accomplished by very large operations which time their discharges to periods of high rainfall.15

There are also guidelines for uses of discharges into aquaculture products (i.e., any aquatic plant or animal). These would apply to those aquaculturists who recycle their waste water by using it as source water for the production or maintenance of sea plants and animals.16

Despite the existence of many regulations, aquaculture will probably remain relatively low on the priority list of the EPA as a point source or discharger of pollution. The EPA is currently focusing its efforts on controlling non-point sources (i.e., sources with no clearly identifiable point of discharge). However, aquaculture facilities will most likely be included in area-wide storm water management plans being developed on a state-by-state basis using federal guidelines to control pollution from non-point sources. 17 Regulatory agencies are primarily concerned with aquaculture facilities which use open- and semi-closed culture systems (systems which have some direct connection with open bodies of water). These systems, including raceways (long, rectangular areas where fish are confined) and pens, more easily pollute surface and ground water (water beneath the earth's surface that supplies wells and springs) than indoor, recirculating systems. Indoor systems use less water and integrate waste water treatment into their production process. Shellfish nurseries and grow-out operations (where fish are brought up to market size) are not considered as having a discharge; in fact they are often viewed as water-improving activities. They are still subject to environmental review for leases, siting, and harvest limitations.18

Solid wastes produced by aquaculture facilities are regulated separately. Solid wastes include fish carcasses and the suspended solids removed from liquid waste. When the solids are removed and become settled, sludge is formed. Some states classify and regulate sludge as an industrial or municipal waste. Other states consider it to be an agricultural waste because of its value as a nutrient source. Fish carcasses are classified as either an agricultural or as a non-hazardous solid waste.19

Sludge may be used as an agricultural crop fertilizer. Most states have guidelines or regulations for the use of manures and other organic wastes (including waste water). The sludge must be free of disease-causing agents, heavy metals, and other contaminants. Composting of the carcasses for use as a soil conditioner is becoming more popular; sometimes it is preferred to land disposal. The carcasses may be recycled into fish meal (mealy substance produced from fish or fish parts) or liquid.20

Regulations of aquacultural solid waste vary from state to state. For those states which consider settled solids and fish carcasses to be animal manure, crop residue, or farm by-products, aquacultural solid waste, like all agricultural waste, would be exempt from solid waste regulation. Some states require permits for the use of sludge as fertilizer. Small scale, non-commercial operations may be exempt from state solid waste regulations and permit requirements if the waste is used on-site following recommended application guidelines.21

This brief summary of pollution control in aquaculture shows that regulation is in place. However, it seems that there are ways by which individual aquaculturists, both large and small, can avoid regulation. For example, very large operations which discharge waste water at certain times of the year are not required to obtain NPDES permits. Small-scale, non-commercial facilities may also be exempt from regulation if they use their wastes on-site. Considering the environmental effects of land and water pollution, the reader may rightly question whether aquacultural effluent and solid waste are adequately controlled.

Environmental Impacts of Aquaculture

We know that more than 50% of total world aquacultural production comes from the coastal zone. This includes over 90% of all cultured mollusks, crustaceans, and seaweeds.22 How does coastal aquaculture impact this environmental zone?

Raising aquaculture species in concentrated areas causes overloading. This means that there is more carbon and nitrogen present in the water from fish waste products and fertilizer. The added elements result in an increase in unwanted species and a reduction in the dissolved oxygen essential to aquatic plants and animals.23 Environmental overloading occurs when the environment is used so far beyond its capacity that the area becomes "spent." What was once thriving habitat for native species is no longer so.24 Aquaculture in developing countries has contributed to the destruction of mangrove forests. In Brazil, for example, so much destruction has occurred that the local climate has changed. It has changed to such a large degree that some aquacultural operations have had to shut down.25 Without mangrove habitat, the environment is also degraded in other ways. For instance, without mangroves as a buffer system, there is decreased protection of the shoreline against erosion and storm damage. There is also loss of nursery ground for native fish and shrimp larvae.26

Coastal aquaculture can also impact native species when cultured species intermingle with native species. For instance, cultured animals may escape into the wild and breed with non-farmed animals. The high concentration of cultured fish or shellfish may lead to outbreaks of disease which in turn spread to the wild. Use of antibiotics in fish on farms where the concentration of aquatic animals is high could lead to a weakening of the antibiotics' effectiveness.27 There has already been a case of a species of sea lice which had developed resistance to drugs used to treat it in cultured stocks.28

In developing countries, aquaculture may also have an effect on the local human population. Intensive aquaculture has adversely affected the livelihoods of local shrimp farmers in Southeast Asia and in Latin America by diminishing the farmers' ability to feed themselves and their communities. The locals' extensive techniques (methods which use minimal technology) to produce fish are far outpaced by the techniques of intensive (highly mechanized) aquaculture. Furthermore, the locals' fish are bought by the intensive aquaculturists to be used in shrimp feeds. The result for the locals is often a decrease in self-sufficiency.29

Governments, international organizations, and aquaculture associations are recognizing the need to address these and related environmental issues. Several proposals have been suggested with the aim of reducing the environmental impacts of aquaculture. The proposals include the formulation of coastal aquacultural development and management plans. The plans include the establishment of site selection criteria and the use of computer modeling.30 Other proposals address the issues surrounding wastewater management. Proposed suggestions include the following: site rotation, co-culture of species at different levels of the food web, and reduction/rotation in the use of antimicrobials used to kill disease-causing agents.31 These proposals aim to avoid the problems associated with a monoculture (a crop where only one type of plant or animal is grown), and those associated with repeated use of a certain drug. Aquaculturists hope that these and related strategies will alleviate the problems experienced in Western aquaculture.32 They also hope that the strategies will prevent the reccurrence of the same problems in countries where aquaculture is newer. The author will comment on these proposals in the analysis at the end of the article.

The Future of Aquaculture

What will aquaculture look like in the 21st century? Here are a few ideas based on strategies which aquaculture has developed as part of its waste management systems.

Integrated farming is one method used by aquaculture in which nutrients are recycled. It may take several forms, such as aquaculture-agriculture systems. Rice-fish culture is included in this category. There are also poultry-fish systems and soybean-fish culture. Italy boasts an integrated lagoon management system known as vali-culture in which traditional fishery practices, modern aquaculture, and recreational activities co-exist.33 Aquacultural waste is an inexpensive source of minerals and organic matter and can be used as fertilizer on cropland. It could also be used as a nutrient source in the feeds of agricultural animals, such as using catfish processing waste in poultry feeds.34 In the U.S. fish processing industry, wastes are used to produce fertilizer for crops.35 Similarly, using manures from other animals as fertilizer in aquaculture is another example of nutrient recycling in an integrated aquaculture-agriculture system.36

There is growing interest in using treated human waste water in aquaculture. Such a system is already operative in Asia.37 This interest is generated by the rapid spread of urbanization. Using human excreta in aquaculture, as in agriculture, will close the nutrient cycle, encompassing all members of the food web. It has been predicted that the waste water treatment plants of large cities will become centers of food production on a grand scale.38 Another strategy used by aquaculture to recycle its waste products is through composting. This process could be like that of the fisheries industry, where fisheries' wastes (offal) are mixed with Sphagnum peat and composted. The production of the offal-peat compost is an easy and economically feasible way to produce a nutrient-rich fermentation medium for fungi.39 Research has also examined the feasibility of using catfish pond sediment (pond mud) as a growing medium for bell peppers. They found it to be quite satisfactory as compared with field soil.40

There is, in fact, a growing connection between aquaculture and vegetable hydroponics (the cultivation of plants without soil). This integrated system relies on water recirculation. Therefore, it has great potential in regions where water is scarce. The water from fish culture provides most of the nutrients required by plants (a few are added to the water). Nutrient uptake by plants improves water quality and can increase fish production.41 Because chemical pesticides are very toxic to fish, biological methods to control plant pests and diseases are currently under investigation. Such research should be useful in traditional agricultural systems as well. Thus far, experimental integrated systems have produced good yields.42

Author's Analysis

This article has presented the reader with a large volume of facts and figures. How should the reader interpret all of it? Let's look more closely at what the facts mean.

As in Part I of this article, the facts in Part II suggest that aquaculture, from an environmental point of view, has both positive and negative aspects. The information on drugs is the most controversial. The 1991 National Academy of Sciences document which concludes that chemicals in aquaculture are not effectively controlled leads the author to question the safety of aquacultural products. The fact that fish which have received experimental drugs can be sold for human consumption and released into public waters also presents a safety concern.

These facts could have very serious consequences not only for fish eaters, but for all of us. Negative consequences could result from the presence in the environment of uncontrolled and experimental drugs. Residues from these drugs could be released into the water and/or food web, eventually making their way to unsuspecting consumers. This whole affair is worrisome. We should also point out that the large majority of fish eaten in the U.S. is from foreign sources. As mentioned, the number of approved drugs for aquaculture in other countries is much greater. However, we do not know about the testing methods used to approve these drugs, or about the potential risks associated with them. The investigative consumer, with enough persistence, could probably find out from the fish supplier. However, this information is not easily accessible. It is cause for concern.

With respect to effluent regulation, the author found it interesting to discover that most small-scale aquaculture operations are exempt from EPA regulation. It is also noteworthy that some large-scale operations could make themselves exempt from regulation by timing their discharge to certain periods of the year. These facts make the author wonder if effluent and solid waste regulation in aquaculture even exists on a practical level. Furthermore, the fact that shellfish nurseries and grow-out operations are not considered as having a discharge, but, rather, are often viewed as water-improving activities, supports the author's speculation.

When we consider on a global scale how the majority of aquaculture is conducted, we see that aquaculture has a widespread and profound environmental impact. As we reported in Part I of this article, members of the World Aquaculture Society said at their 1996 Annual Conference that aquaculture must seek to be "environmentally friendly." The author certainly agrees with this imperative. Given the damage that aquaculture has created in Brazilian mangrove forests, the surrounding environment, native fish species, and local populations in the developing world, there is no doubt that people in aquaculture need to look closely at how to mitigate the problem.

Granted, aquaculture farmers have begun to look at its practices from an environmental point of view. As we mentioned, there are proposals to formulate aquaculture development and management plans. We hope that these plans will be successful so that everyone, including the environment, wins. However, the author is wary of over-reliance on computer modeling as a solution to serious problems. It can in no way perfectly account for all of the variables which are present in natural systems. Again, we express hope that aquaculture farmers will make prudent decisions based on these models, relying principally on past experiences rather than predictions.

We applaud those in aquaculture for searching for ecological ways to re-use its water and waste. Integra-ted farming and composting are environmentally sound practices. So, too, is vegetable hydroponics. However, aquaculture has far to go before it can be called "environmentally friendly."

Editor's note: Vegetarians do not eat meat, fish, or fowl. The purpose of this article is not to condemn or condone the eating of fish, but to educate readers about the various ramifications of aquaculture.

Readers can send a self-addressed stamped envelope to VRG, P.O. Box 1463, Baltimore, MD 21203, to receive the footnotes for both Part I and Part II of this article. If you would like a printed copy of Part I of this article, send $3 to the above address.


The Vegetarian Journal published here is not the complete issue, but these are excerpts from the published magazine. Anyone wanting to see everything should subscribe to the magazine.

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