The control of chemicals used in aquaculture in Europe

The control of chemicals used in aquaculture in Europe

By M. J. Costello1, A. Grant2, I. M. Davies3, S. Cecchini4, S. Papoutsoglou5, D. Quigley6 and M. Saroglia4

1Ecological Consultancy Services Ltd (EcoServe), 17 Rathfarnham Road, Terenure, Dublin 14, Ireland; 2Spean Bridge, PH34 4YD,Scotland; 3Marine Laboratory, Victoria Road, Aberdeen, Scotland; 4Department of Sciences and Animal Production, AquaculturalSection, University of Basilicata, Via N. Sauro, 85100 Potenza, Italy; 5Laboratory of Applied Hydrobiology, Agricultural Universityof Athens, 75 Iera Odos, Votanikos, 118 55 Athens, Greece; 6Hibernor Atlantic Salmon Ltd, Derryclare, Recess, County Galway,Ireland

Summary

A range of chemicals are used in European marine aquacultureand these may be categorized as disinfectants, antifoulants and

medicines (includes vaccines). This article provides a review ofchemicals used in aquaculture in Europe, their regulatory status,and a checklist of points considered best practice in the use (and

avoidance of use) of medicines in marine aquaculture. Therelease of antifoulants and disinfectants into the marine envi-ronment is controlled by local and/or national waste discharge

regulations that may in turn be guided by wider environmentalquality objectives. The authorization of veterinary medicines,biologicals (vaccines) and pharmaceuticals (chemicals), in Eur-ope is the subject of several ECDirectives. Registration dossiers

address the issues of product quality, safety and e�cacy andinclude environmental and consumer safetywhere the product isdestined for use in a food-producing animal. Fish farmers, like

all livestock producers, must have access to a range of properlyauthorized medicines to safeguard animal health and welfare.The distribution and supply of medicines must be appropriately

controlled and their authorization appropriately includes envi-ronmental risk assessment to a common European Union (EU)or international standard.

There is progress towards the harmonization of the author-ization process within the EU and this will help to ensure thecontinued availability of medicines for ®sh. Consumer safety isaddressed by the setting of maximum residue limits (MRLs)

derived through toxicological risk assessment and by surveil-lance of food for residues of veterinary medicines. The systemfor the environmental risk assessment of chemicals used in

aquaculture is being developed and is outlined in the presentarticle.It is recommended that the supply and use of ®sh medicines

is uniformly regulated in the EU and supported by appropriatecodes of best practice. A number of codes of practice thatinclude reference to the use of medicines have been produced

both at a European level and in member states. It isrecommended that all European marine aquaculture producersadopt a code of best practice for the use of medicinal and otherchemicals their industry. Medicines are one part of an

integrated package in dealing with animal health. This includesenvironmental conditions, nutrition and hygiene. The bestpractice guidelines presented here are based on the outcome of

three European workshops as part of the EU MARAQUAproject that involved industry, government and researchscientists. They cover the avoidance and minimizing of the

need to use medicines and other chemicals, to recording andmonitoring their use and e�ectiveness (in case of resistance

development), exchange of experiences within the industry,and sta� training. Recommendations are also included for

manufacturers of medicines and other chemicals, and forregulatory authorities. Minimizing the need to use medicinesand other chemicals requires attention to a healthy source of

®sh stock. Sta� must be appropriately trained in ®sh husban-dry (to minimize stress), hygiene and disease recognition andtreatment, including management of the farm site to keep it

disease free. The latter may require single generations of ®shper site to allow a fallow period during which a disease orparasite cycle is broken. These recommendations and guide-lines are in accordance with the current codes of practice being

developed by di�erent sectors of the aquaculture industry indi�erent countries. They do not necessarily involve signi®-cantly higher production costs and indeed are more likely to

save costs as medicines and disease impacts are very costly toindustry.

Introduction

A range of chemicals is used in European marine aquaculture

and these may be categorized as disinfectants, antifoulants andveterinary medicines. The term medicine is used here toconform to the legal term used rather than alternative termssuch as chemotherapeutant. It includes antibiotics, anaes-

thetics, ectoparasiticides, endoparasiticides, and vaccines.They are used to control external and internal parasites, ormicrobial infections.

Medicines are commonly used by ®n®sh farms and not byshell®sh farms. However, shell®sh hatcheries may use anti-biotics to control water quality. By far the majority of marine

®n®sh farms culture the ®sh in sea cages, and any chemical thatmay be used is discharged to the open water and sediments.The main species involved are Atlantic salmon, Salmo salar,rainbow trout, Oncorhynchus mykiss, sea bass, Dicentrarchus

labrax, and sea bream, Sparus auratus.

Chemicals used in marine aquaculture in Europe

As part of the MARAQUA project (Fernandes et al. 2000),information on chemicals used in aquaculture in Europe was

obtained for Scotland (Henderson and Davies 2000), Norway(Maroni 2000), Spain (Sanchez-Mata and Mora 2000), Italy(Saroglia et al. 2000), Iceland (Jonsson 2000), Greece

(Papoutsoglou 2000), Finland (Varjopuro et al. 2000), andDenmark (Pedersen 2000), with additional information onsea-lice medicines from Costello (2000). Contemporary

J. Appl. Ichthyol. 17 (2001), 173±180Ó 2001 Blackwell Wissenschafts-Verlag, BerlinISSN 0175±8659

Received: January 26, 2001Accepted: March 26, 2001

U.S. Copyright Clearance Centre Code Statement: 0175±8659/2001/1704±0173$15.00/0 www.blackwell.de/synergy

information was not available for Ireland (McMahon 2000),France (Dosdat and De la Pomelie 2000), Germany (Rosen-

thal and Hilge 2000), Netherlands (Smaal and Lucas 2000),Sweden (Ackefors 2000), and Portugal (Bernardino 2000). Aprevious review by Alderman et al. (1994) found some

information on all countries that were members of theInternational Council for the Exploration of the Sea (ICES)with the exception of Portugal. They found it èxtremelydi�cult' to get information on the use, especially `legality of

use' in each country. Some banned substances were widelyused. The present ®ndings record a di�erent range ofchemicals used in each country and may also be subject to

omissions or errors. However, they serve to con®rm theconclusions of Alderman et al. (1994) that there is insu�cientinformation on the use, and environmental impact, of these

substances at a European scale.

Medicines

Sea lice are the most common and economically signi®cantparasite in Atlantic salmon farming and a range of veterinarymedicines is used to control them (Table 1). Their active

ingredients are dichlorvos, azamethiphos, hydrogen peroxide,ivermectin, emamectin, cypermethrin, deltamethrin, te¯u-benzuron, and di¯ubenzuron. Two antihelminthics have been

approved for control of trematode worms in two countries,and a third substance has been used under the cascade systemfor cestode worms in Scotland (Henderson, personal comm.)

(Table 1). A smaller range of antibiotics is used and thedevelopment of vaccines is reducing the use of antibiotics.Better husbandry and hygiene, including single-generationsites and fallowing in the case of Atlantic salmon farming, are

also reducing the need for medicines.Chloramphenicol, furazolidone and dimetridazole, are listed

in Annex IV and speci®cally banned for use on all food-

producing animals, although they have been used in aqua-culture in parts of Europe. The analytical methodology formonitoring medicines and other chemicals in ®sh needs be

related to methods in the amount prescribed, in the food andin the environment. For example, in Italy, a trout farmer wasaccused of using chloramphenicol. However, this substance isdetected at only 100 lg g±1 in ®sh feed, but 1 lg g±1 in ®sh

®llet, and it is possible that the farmed ®sh may unknowinglyaccumulate such substances from contaminated ®sh feed(Saroglia, personal comm.). Furazolidone was used widely in

aquaculture in the past as an antibacterial (Alderman et al.1994). Chloramphenicol is banned because of its importancefor human medicine and concern over the spread of drug

resistance.Vaccines are increasingly replacing the use of antibiotics in

aquaculture and they are often provided in di�erent formu-

lations and combinations. Vaccines against the widespreadbacteria Aeromonas salmonicida, include Aquavac Furovacand Aquafur, Furogen (several formulations of each), Biojec1500 1800, and against Vibrio anguillarum include Aquavac

vibrio and Vibrogen. Combined vaccines against Aeromonassalmonicida and Vibrio anguillarum are Norvax and FUR VIB.There are also vaccines against the bacterium Yersinia ruckeri,

including Ermogen, and Aquavac ERM.

Disinfectants

Formalin and iodophors are the most widely used disinfect-ant in European aquaculture. Both have a maximum residue

limit (MRL) and marketing authorizations (MA) in mostcountries.

Antifoulants

The present generation of antifoulants are mainly copperbased and are sold under many trade names (examples fromUK in parentheses below from Henderson and Davies 2000):· copper (Intersleek BXA 810/820 (Base), Amercoat 70E,

Amercoat 70ESP, VC 17 MM-EP);· copper oxide (Waterways, Aquasafe, Bottomkote, NetrexAF, Norimp 2000 Black, Interclene Premium BCA300

Series);· copper oxide and dichlo¯uanid (Aqua-Net, Copper Net,Hempel's Antifouling Rennot 7150 and 7177);

· copper oxide and dichlo¯uanid and zinc oxide (Net-Guard);· 2,4,5,6-tetrachloro isophthalonitrile (Flexgard IV and VWaterbase Preservative);

· 2,4,5,6-tetrachloro isophthalonitrile and copper sulphate

(Flexgard VI Waterbase Preservative);· 2,4,5,6-tetrachloro isophthalonitrile and copper oxide(Flexgard VI);

Some brands have no recognized active (i.e. toxic) ingredient(Interclene AQ HZA700; Intersleek FCS HKA580, FCSHKA560, BXA 560 Series (Base); Bioclean (DX). Copper

and zinc are listed under the EU Dangerous Substanceslegislation and as such their release to the environmentrequires control. Antifoulants are biocides and are not directly

used on food-producing ®sh. Thus they do not fall under theMRL system. However, where used, ®sh are exposed toantifoulants for months. Their use may be controlled underdischarge permits.

Regulation

Medicines can be pharmaceutical (chemical) or a vaccine(biological). In Europe a product may be subject to threeforms of assessment:

· an MRL in the ®sh ®llet;· an MA that approves use in the manner and environmentproposed for the species in question and;

· in some cases a permit for discharge to the environment.

Disinfectants and wash-water from nets with antifoulantsusually require a discharge permit. Food additives andimmunostimulants were not considered in this project.

Before a medicine is used on food ®sh in the EU, it shouldhave an MRL by being annexed in EC Council Regulation2377/90. It should additionally have an MA for use on ®sh

(Alderman 1999). There is now co-ordination of MRLdesignations and MAs within the European Union by theEuropean Agency for the Evaluation of Medicinal Products

(EMEA) (established under Council Regulation 2309/93). TheEMEA further seeks to harmonize medicine authorizationswith other countries in Europe and beyond (EMEA 2000).However, applications for an MA for aquaculture medicines

are usually submitted to national authorities of EU memberstates for assessment.

The aim of the MRL is the protection of the consumer from

adverse e�ects residues. The MRL, e�cacy, user safety, andenvironmental e�ects are considered within an MA. As anMRL is a prerequisite for the use of veterinary medicines their

MRL status are provided in Table 1. Under the cascadesystem (Article 4, Council Regulation 81/851/EEC), a veter-inarian may prescribe a medicine that already has an MA (and

174 M. J. Costello et al.

Table

1Medicines

usedin

marineaquaculture

inEurope.

Theactiveingredient,tradename,

anddisease

orparasitestreated,are

shown.Sea

lice

refers

toboth

ofthespeciesofcopepodparasites,Lepeophtheirus

salm

onisandCaliguselongatus

Application

Activeingredient

Tradenames

MRLstatus

MA

foruse

on®sh

in

Anaesthetic

Phenoxyethanol

Iceland

Anaesthetic

Quinaldine

Anaesthetic

Ketamine

Annex

IIallspecies

Notusedfor®sh

Anaesthetic

Procaine

Annex

IIallspecies

Notusedfor®sh

Anaesthetic

Benzocaine

Annex

IIbutnotfor®sh

as

Norw

ay

only

topicaluse

approved

Anaesthetic

Tricainemethanesulphonate

MS222,Metacain

Annex

II1

Norw

ay,Iceland

Antihelminthic

Levamisola

Spain

prov.

Antihelminthic

Mebandazole

Denmark

Antihelminthic

Fenbendazole

Panacur

Bacterialinfections

Ampicilin

Spain

Bacterialinfections

Apramycinsulphate

Apramycin

Bacterialinfections

Chlortetracycline(a

tetracycline)

aSpain

Bacterialinfections

Erythromycina

Notlicensedin

Europebutusedelsewherea

Bacterialinfections

Flumequin

(aquinolonecompound)a

Norw

ay,Spain,Italy

Bacterialinfections

Amoxicillintrihydrate

aVetremox,Aquacil800,Micromox,

Annex

IItaly,Iceland,UK

(Scotland)

Clamoxylsoluble

powder

Bacterialinfections

Oxolinic

acid(a

quinolonecompound)a

Aqualinic

powder,Aquinox

Annex

INorw

ay,Spain

prov.,Iceland,Greece,

Finland

Bacterialinfections

Oxytetracycline(a

tetracycline)

aTetraplex,Aquatet

Annex

ISpain,Italy,Greece,

Finland,UK

Bacterialinfections

Sara¯oxacin(a

quinolone)

Sara®n

Annex

ISpain

Bacterialinfections

Sulphonamides

(e.g.Sulphadiazine

Sulfatrim

,Tribrissen

40%

powder

Annex

ISpain,UK,Norw

ay,Spain,Italy,Iceland,

potentiatedwithTrimethoprin,

sulfamids)a

Greece,

Finland,Denmark

Bacterialinfections

Florfenicol

Annex

III

Norw

ay,Spain,Denmark

Disinfectant,fungicide,

parasiticide

Form

alina

aqueoussolutionofform

aldehyde

Annex

IIforallspecies

Widespreaduse

Disinfectants,usedonsalm

onid

Iodophors

aWescodyne

Annex

IIforallspecies

Widespreaduse

eggsandequipment

Injectable

horm

one

Buserelinacetate

Receptal

Notforfood®sh,butmay

beforbroodstock

Sea

lice

Deltamethrin

AlphamaxVet

Norw

ayprov.

Sea

lice

Dichlorvosa

Aquagard,Nuvan

(nolonger

MA

inUK)

Sea

lice

Di¯ubenzuron

Lepsidon

Norw

ayprov.

Sea

lice

Pyrethrum

Py-Sal

Sea

lice

Emamectin

SLIC

EAnnex

IUK

Sea

lice

Ivermectina

Ivomec

Pre-m

ixforpigs

Annex

Ibutnotfor®sh

Sea

lice

Hydrogen

peroxide

Salartect350&

500,Paramove

35&

50

Annex

IINorw

ay

Sea

lice

Azamethiphos

Salm

osan

Annex

III

Norw

ay,UK

Sea

lice

Cypermethrin

Excis

Annex

III

Norw

ayprov.,UK

Sea

lice

Te¯ubenzuron

Calicide,

Ektobann

Annex

III

Norw

ayprov.,UK

Annex

I=

hasanMRL;II

=noneedforanMRLasresidueissafe;III=

provisionalandtemporary

MRLonly;IV

=banned

foruse.Whether

substanceshaveamarketingauthorization(M

A)in

Norw

ay(M

aroni2000),Spain

(Sanchez-M

ata

andMora

2000),Italy

(Sarogliaet

al.2000),Iceland(Jonsson2000),Greece(Papoutsoglou2000),Finland(V

atjopuro

etal.2000),andDenmark

(Pedersen

2000)isindicated.Prov.=

provisionalortemporary

MA.

aDetailsonthesesubstancesin

Aldermanet

al.(1994).

Control of chemicals used in aquaculture in Europe 175

so also an MRL2 ) for a non-®sh animal where no suitablyauthorized medicine with an MRL exists for ®sh. A minimum

withdrawal period of 500 degree±days applies in theseinstances. However, this èxtra-label' use should only beused by veterinarians èxceptionally' and ùnder their direct

personal responsibility' (EMEA, personal comm.) ìn ananimal or small number of animals on a particular holding'(Article 4, Council Directive 81/851/EEC). Thus, where anMRL exists, although not for ®sh, this is noted in Table 1

where it is possible that these substances may be used onfarmed ®sh. In the absence of approved medicines for ®sh,extra-label prescription by veterinarians for ®sh farms at one

time became common. However, medicines with an MRL arenow available for ®sh pathogens and it would be exceptionalfor a veterinarian to be able to justify prescribing a medicine

without an MRL for ®sh.Salmonids are a `major food-producing species' and thus the

above rules with regard to extra-label use would normallyapply (CVMP 1997a).

Since 1 January 2000 any substance not listed in Annex I, II,or III of Council Regulation 2377/90 is e�ectively banned fromuse. Individual member states are responsible for removing

these substances from the market and monitoring illegal use(EMEA, personal comm.). To summarize the decision-makingprocess for a veterinarian, they must use medicines in the

following order:· a veterinary medicine authorized for use in another species,or for a di�erent use in the same species. The latter might be

preferred for a food-producing species as the withdrawalperiod for the same species3 could be used, provided the dosewas lower or the same as for the authorized use;

· a medicine authorized in the Member State concerned for

human use;· a medicine to be made up at the time on a one-o� basis(extra-contemporaneous) by a veterinary surgeon or a

properly authorized person.With each step the veterinarian takes greater responsibility

for risks to the animals being treated and the environment, and

must be able to weigh the bene®ts over these risks, and justifythese actions.Fish farms may use a range of antifoulants and disinfect-

ants that discharge toxic chemicals to the environment.

These are subject to a di�erent regulatory procedure toveterinary medicines, and now come within the scope of theBiocides Directive. An MRL is not applicable to these

substances but the appropriate national authority mustlicense their release to the environment. As they are notannexed in the MRL Directive, their residues should not be

present in food ®sh.The ®rst conclusion one can draw from the information

available (Table 1) is that the MA status varies signi®cantly

between countries and is not concurrent with the MRL system.In addition, the distribution and supply of medicines is notharmonized within Europe and prices can vary greatly betweencountries, leading to opportunities for illegal sales. There

would appear to be considerable potential for increasedco-ordination of the approval of ®sh medicines within theEU and its trading countries. This should increase the

availability of approved medicines through the (`mutual')recognition of MA between countries making it less costly forsuppliers to extend their market. This would bene®t manufac-

turers in increased sales, reduce extra-label use, and clarify inthe minds of industry and local authorities what should andshould not be used in aquaculture.

Environmental risk assessment

Environmental risk is considered in the evaluation of applica-tions for an MA; a process that may be conducted through

individual member states, or exceptionally by the EMEACommittee for Veterinary Medicinal Products (CVMP). Onceapproved in one member state, other member states have

90 days to mutually recognize this approval if the applicantwishes. This process is facilitated by the Veterinary MutualRecognition Facilitation Group, which has produced a `bestpractice guide' on the subject (VMRFG 1999). However, even

with an MA, the release of a medicine to the environmentnormally requires a licence from the national authority. Thisre¯ects the need for national authorities to consider local

environmental conditions (e.g. other uses of the water, dilutionand degradation rates) in permitting discharges of wastes towater. Such discharges in the marine environment are also

subject to national regulations, and trans-national Europeanagreements governing the north-east Atlantic (notablyOSPARCOM) and Mediterranean (notably the Barcelona

Convention).The CVMP released European guidelines for environmental

risk assessment of veterinary medicinal products in 1997(EMEA/CVMP/055/96-Final; CVMP 1997b)4 . These guidelines

include requirements for ®sh medicines. There is a tieredapproach to environmental risk assessment (Fig. 1):· Tier 1

· chemical/physical properties, abiotic degradation inwater;

· acute toxicity to aquatic species.

· Tier 2· further laboratory data on fate and e�ects;· data needed dependent on product and ®ndings at Tier 1.

· Tier 3

· modelling of dispersion in marine environment;· ®eld data to validate models;· ®eld data on e�ects, e.g. ± sentinel species studies, single

site biological monitoring.A new international initiative is the International

Co-operation on Harmonization of Technical Requirements

for Registration of Veterinary Medicinal Products (VICH).VICH is a trilateral programme aimed at harmonizingtechnical requirements for veterinary product registration.

The parties to VICH are the EU, USA and Japan. In addition,Australia and New Zealand participate as observers. The nine-step process involves both regulators and the veterinarypharmaceutical industry as equal partners. Once adopted,

the VICH recommendations should replace correspondingregional requirements. One of the bene®ts of harmonization isthat a common data package can be used for authorization

throughout the world. One of the current topics is ecotoxicity/environmental impact assessment (EIA). Phase I guidance forenvironmental risk assessments has already been agreed and

released. This is ènvironmental impact assessment (EIAs) forveterinary medicinal products (VMPs) ± Phase I': recommen-ded for implementation at Step 7 of the VICH Process on 15June 2000 by the VICH Steering Committee.

Work is currently in progress on the Phase II guidance,which will detail the environmental fate and e�ects studiesneeded as part of the authorization process for veterinary

medicinal products. Only pre-consultation drafts of the guid-ance documents are available at present. There will be furtherrevisions to this draft before the public consultation stage,

possibly during 2001.


Public con®dence in the safe use of chemicals

Intensive aquaculture is a new and very rapidly growing,intensive, technically complex industry in Europe. It has grownfaster than the rate of development of regulations, and the rateof publication of data about its environmental impacts. There

has been and is great public concern about the use of chemicalson ®sh farms, from the point of view of tissue residues and

environmental impacts. The public has limited faith inindustry, scientists and government authorities to protectthem, because of past and recent incidents regarding foodquality. When it comes to food quality, the public has a very

low tolerance that is not related to the actual quantitative risk.The growth in the òrganic' food market, and widespreadpublic unease about genetically modi®ed foods, are examples

Fig. 1. The ecotoxicity guidelines in the CVMP tiered approach to environmental risk assessment (from EMEA/CVMP/055/96)


of the increased interest and power of the consumer. It takesonly one deliberate or accidental contamination of food, or

signi®cant environmental impact, to damage the reputation ofan entire industry.Typically, medicines used in aquaculture are adopted from

other areas of chemical use, notably agriculture. For new ®shmedicines, tests are required as to the e�cacy and toxicity ofthe chemical to ®sh, tissue residues, degradation in the marineenvironment, and ecotoxicity to marine life in order to obtain

an MA. However, some farms have used some compoundsbefore this range of studies is complete, for example as part ofan experimental testing programme. This use is either under

special veterinary prescription (the `cascade' system where theveterinarian considers it the only suitable treatment), or on atrial or research basis. There is usually a further period of time

(1±3 years) before the results of this research are published, ifthey ever are. This release is at the discretion of the applicantcompany (i.e. the medicine manufacturer or supplier).It is not possible for authorities to provide transparency in

authorization of medicines due to the con®dentiality require-ments of the legislation. This results in some chemicals beingused in aquaculture before information is available to the

public and environmental and consumer groups becomeconcerned and protest. These concerns receive a lot moremedia attention than the conclusions of risk assessments, with

the consequent impression to the wider public that the use ofmedicines in aquaculture is a risk to their diet and theenvironment.

Faced with a public distrust of industry, sceptical ofscientists, and with limited faith in governments; how canthe system be improved to increase public con®dence thatfarmed ®sh are safe to eat and that the use of chemothera-

peutants is not harmful to the environment? There is a need forthe industries involved, regulatory authorities, and scienti®ccommunity to pro-actively build con®dence in their activities

and advice by demonstrating that they are addressing publicconcerns. Each of these sectors has di�erent main concernswith respect to the use of chemicals in aquaculture (Table 2).

One approach to increasing public con®dence in aquaculturewould be a public information campaign to increase awarenessof the regulatory system in place, and demonstrate enforce-ment of regulations (e.g. release of monitoring data). There

should be a more rapid release of information on chemicals,notably on tissue residues, risk to consumer, and environmen-tal impacts. Results of residue surveillance by EU member

states are generally available from the national authorities asrequired under EU Directive 96/23/EC. This applies not onlyto food ®sh produced in Europe, but those imported into

Europe. The existing regulations for the control of chemicals inaquaculture are adequate, but the licensing system for chem-icals is complex and unclear to ®sh farmers and the public. It

would be most appropriate that government authorities lead

this campaign because it would lack credibility if led byindustry.

The aquaculture industry should develop working relation-ships with consumer groups at European and national levels.This interaction should serve to make aquaculture and a

consumer organization aware of each other's concerns, andexchange information and opinions. This knowledge wouldallow the aquaculture industry to prioritize its attention toissues of greatest public concern with consequent marketing

applications.Manufacturers and/or suppliers of medicines and chemicals

used in aquaculture need to make information required for risk

assessment publicly available as soon as possible. Theirscientists, and the wider community of scientists, shouldcommunicate this risk to the public and consumers as clearly

as possible. This should allow the public and consumerorganizations to place this risk in the context of other risksto the health of the public and environment.

Despite the absence of published information on particular

aspects of aquaculture±environment interactions, there arethousands of scienti®c publications on the subject. As part ofthe MARAQUA project, a bibliography of environment-

related aquaculture literature was compiled by the combina-tion of databases held by the Institute of Marine Biology atCrete (IMBC) (HTTP://www.imbc.gr) and Ecological

Consultancy Services Ltd (HTTP://www.ecoserve.ie) in Dub-lin. This includes hundreds of references to publicationsconcerning the use of medicines and other chemicals in

aquaculture in Europe and elsewhere and is accessible at<HTTP://idd-25.imbc.gr/biblio_serv/bimaque.html>.

Recommendations for best practice

This study reviewed three previous recommendations for bestpractice in aquaculture:

· in 1994, the Paris Commission for the Protection of theNorth Sea and north-east Atlantic passed a recommenda-tion on best environmental practice in relation to marine

aquaculture;· at a global level GESAMP (1997) published guidelines forthe use of chemicals in coastal (freshwater, brackish andmarine) aquaculture;

· the main use of ectoparasticides in marine aquaculture is tocontrol sea lice. Best Practice for the control of sea lice onsalmon farms was published in the newsletter Caligus No. 5

(1998, pages 18±19, available at HTTP://www.ecoserve.i.e./projects/sealice).Similar principles are common to all three documents,

namely prevention, use of alternative treatments, and prudentnon-prophylactic use of chemicals. Medicines are one part ofan integrated package in dealing with animal health. This

includes environmental conditions, nutrition and hygiene. Onthe basis of these guidelines and the authors' personalexperience a set of guidelines for best environmental practicewas discussed and approved over two European workshops

as part of the MARAQUA project. These guidelines orrecommendations (Table 3) are self-explanatory. For ®shfarms, they cover avoiding and minimizing the need to use

medicines and other chemicals, to recording and monitoringtheir use and e�ectiveness (in case of resistance development),exchange of experiences within the industry, and sta�

training. Recommendations are also included for manufac-turers of medicines and other chemicals, and for regulatoryauthorities.

Table 2Areas of concern to the di�erent sectors a�ected by the use ofchemicals on ®sh farms

Sector Area of main concern

Manufacturer Future sales of productIndustry E�cacy of productAuthorities Of safety for consumer, environment and farm sta�Consumer Tissue residues in foodPublic Environmental impactNews media E�ective control system in operation (enforcement)


Minimizing the need to use medicines and other chemicalsrequires attention to a healthy source of ®sh stock. Sta� mustbe appropriately trained in ®sh husbandry (to minimize stress),hygiene and disease recognition and treatment, including

management of the farm site to keep it disease free. The lattermay require single generations of ®sh per site to allow a fallowperiod during which a disease or parasite cycle is broken.

These recommendations and guidelines are in accordance withthe current codes of practice being developed by di�erentsectors of the aquaculture industry in di�erent countries. They

do not necessarily involve signi®cantly higher production costsand indeed are more likely to save costs as medicines anddisease impacts are very costly to industry.

Acknowledgements

This paper is a contribution to the MARAQUA Concerted

Action project funded by the European Commission FAIRaquaculture research programme (project number FAIRPL98±4300). We thank the participants to the project

Table 3Towards `best environmental practice' in the use of medicines on marine ®sh farms

Prevention (avoidance)Maintain farm production levels in balance with local environment and ecologyUse sites with consistently good water qualityOnly stock with ®sh of known disease statusMinimize stocking densities with due consideration of ®sh behavioural needsFallow sites for several weeks between stocking when using cage systems.Use cleaner-®sh (wrasse) for sea-lice control where compatible with availability of wild stocksApply strict hygiene procedures (cleaning, disinfection, etc.) in land-based systemsKeep di�erent generations separate in land based systems and use single generation sites in cage systemsTrain sta� in strict hygiene practices, including disinfection proceduresAvoid sta� and equipment movements between di�erent areas of the farm and between farmsChange cage nets so as to use a wide as mesh as possible to minimize fouling problemsMinimize changes of nets so the use of antifouling paints is minimizedUse physical methods to clean nets (e.g. underwater net cleaners, drying, spraying with power-hoses)Use good quality feedUse vaccination in order to prevent diseases at the optimal time (right size, good health condition, good environmental conditions, etc.)Regularly remove dead ®sh from cultivation system in order to prevent spread of diseases

Monitoring or surveillanceMaintain records of ®sh movements, growth, feeding, environmental conditions (especially temperature, salinity and oxygen or otherimportant parameters according to di�erent rearing systems)

Maintain records of ®sh health and details (doses, duration, frequency) of health treatments, including vaccines, antibiotics, and parasitecontrol

Use professional veterinarians to regularly monitor ®sh healthMonitor therapeutic treatments and their successMonitor for development of resistance to a chemotherapeutantSubject records to analysis by appropriately quali®ed sta� to detect factors that may be in¯uencing ®sh healthExchange information with neighbouring farms because problems and solutions are likely to be common

Sta� trainingTrain farm sta� to minimize stress to ®shTrain farm sta� in early detection of poor health in ®shTrain sta� in keeping clear and accurate records and data managementTrain sta� in application of treatments to ensure accurate dosages or concentrations

TreatmentOnly treat ®sh following veterinary examination of the ®sh, con®rmation of the problem, and assessment of the appropriate treatment(e.g. accounting for resistance of bacteria or lice)Follow veterinarians and manufacturers instructions for a treatmentDo not use antimicrobials prophylactically except as part of a carefully planned treatment strategyCollect unused chemicals for safe disposal or reuse (e.g. under-cage feed collectors, tarpaulin baths) where it is possiblePlan for, and alternate, treatments to prevent development of resistant populations (especially important for widespread problems suchas sealice, Aeromonas, Vibrio and Pasteurella)

Develop regional scale co-ordinated approaches for sea-lice control, including winter treatmentsUse freshly prepared medicated feed prepared by authorized feed manufacturersObserve any withdrawal period after chemical treatment to ensure that residual levels observe MRL values

Manufacturers and suppliersMake information on the toxicology and ecotoxicology of chemotherapeutants publically available as soon as possiblePublish studies assessing the risk of the chemotherapeutant to the consumer (tissue residues) and environmentHighlight problems requiring chemical use to producer organizations and research funding organizations (e.g. European Commission,national agencies) so as to in¯uence the prioritization of research funding

Regulation by authoritiesMonitor, audit, and report to the public on the use of chemicals on farms and their prescription by veterinariansVerify that farm management and sta� are appropriately trained to monitor and manage ®sh health, including the use of chemicalsCollate, analyse and report on quantitative data concerning the chemicals used on each farm, and the industry as a whole. This informationis a good indicator of trends in disease management

Establish an approval system for drugs and chemicals to be used in aquaculture that is co-ordinated between government agenciesand European Union member states

Control and regulate the amounts of chemical residues found in aquaculture productsSupport the development of appropriate management agreements between neighbouring ®sh farms on the use of high quality stock anddisease prevention


workshops that contributed to the discussions resulting in thispaper, Carol Long (VMD), Anne Henderson (SEPA), Kornelia

Grein (EMEA) and Karen Miller (Napier University) forhelpful comments, and the Veterinary Medicines DirectorateFish Group in the UK.

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Authors' addresses: M. J. Costello (present address), HuntsmanMarine Science Centre, 1 Lower Campus Road,St Andrews NB, Canada. ES'B 2L7; EcologicalConsultancy Services Ltd (EcoServe), 17 Rath-farnham Road, Terenure, Dublin 14, [email protected]; A. Grant, Spean Bridge,PH34 4YD, Scotland; I. M. Davies, MarineLaboratory, Victoria Road, Aberdeen, Scotland;S. Cecchini, M. Saroglia, Department of Sciencesand Animal Production, Aquacultural Section,University of Basilicata, Via N. Sauro, 85100Potenza, Italy; S. Papoutsoglou, Laboratory ofApplied Hydrobiology, Agricultural University ofAthens, 75 Iera Odos, Votanikos, 118 55 Athens,Greece; D. Quigley, Hibernor Atlantic SalmonLtd, Derryclare, Recess, County Galway, Ireland


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The control of chemicals used in aquaculture in Europe