For the purpose of this document, “ecology” is defined as the study of the interrelations of aquatic plants or animals with their environment. The “environment” is everything that may influence an organism's chance to survive and multiply (i.e., physical/chemical characteristics of water, food, other organisms, habitat etc.)
Throughout the section, no distinction is made between an aquatic organism proposed for introduction to a natural ecosystem (release to the wild) or one proposed for other purposes, such as enclosures. It is assumed that escape is an inevitable consequence of most applications, thus presenting the same potential problems as a release to the wild.
An aquatic introduction or transfer brings with it the possibility of effecting a variety of ecological changes (good or bad), directly or indirectly, on indigenous species in the target area. No group of biologists, ecologists or geneticists is able to predict with certainly the results of an introduction of a foreign organism. It may be that the behaviour of an organism, although well known in its native habitat, will be considerably different in a new habitat. Once introduced, a new species may be difficult if not impossible to eradicate, if it is later found in the short or long term to be undesirable.
Because of the ecological complexity related to introducing or transferring a marine or freshwater organism and because it is unlikely that adequate information will be available from the literature on which to base an assessment of likely interrelations with indigenous species, it is important that a thorough examination of any proposal be conducted. This would include:
3.1.1 Examination of the physical and chemical characteristics of the native environment of the introduced species, as well as the new environment to which the species will be introduced.
3.1.2 A full biological analysis of the aquatic organism proposed for introduction, both within its natural range and where previous transplants have taken place (if applicable). This review should cover, but is not restricted to, the following aspects:
disease history
3.1.3 Assessment of the new location for the species with respect to indigenous species likely to interact with introduced species, and with respect to the likelihood of the species establishing wild reproducing stocks.
3.1.4 Examination of potential implications of any new fishery which may develop for the introduced species in relation to harvesting of indigenous species (fishing pressure).
3.1.5 Examination of control methods to prevent overpopulation by the introduced species or even for its total eradication if necessary.
3.1.6 Discussion of possibilities for phasing in introduction through an initial controlled planting to study trophic interaction with indigenous fauna, followed by a full-scale introduction should no problems be encountered.
3.1.7 Long-term monitoring of the dynamics of a species in its new environment to ensure indigenous fauna is not affected detrimentally. This monitoring should utilize baseline data collected in the pre-release period as a reference point on which comparisons can be made.
The genetic implications of introducing or transferring aquatic organisms to a new environment are complex and poorly understood, both with respect to their effects on the organisms imported and on the resident species. It has been shown from animal and crop breeding work that manipulation to adapt species to new environments and to produce certain desirable characteristics results in the “narrowing in the genetic base of the species” (FAO Technical Paper #217, 1982). In the process of this manipulation, genetic determinants controlling disease resistance and fitness in marginal environments may be lost at an early stage.
Warnings from biologists, geneticists, and ecologists state that genetic diversity is essential for the preservation of a species and that importation of new species or strains of aquatic organisms could alter this diversity. The natural gene pool of a stock or species may be directly altered by the new genes, if interbreeding occurs, or indirectly through modification of the physical or biological environment of resident species by the import.
Utter 1981, in discussing distinct salmonid populations states, “In addition, transplantations interfere with heritable patterns of homing precision (Ricker 1972) and further complicate innate differences among species in the formation of discrete population groupings”.
A conservative attitude towards introductions and transfers has been advocated by the ICES Working Group on Genetics at their 1985 meeting (C.M. 1985/F:59/Sess. T) including the suggestion that only non-breeding or sterile individuals be deliberately released. This approach would avoid potential reduced fitness and introgression of genes from such stocks on indigenous species.
The following recommendations are aimed at decreasing the risks of genetic disruption resulting from the introduction or transfer of exotic species or strains:
3.2.1 Carry out a thorough risk analysis (genetic, ecological etc.) prior to any introduction. This should include the accumulation of background data related to the history of the species to be introduced in its “home” waters and in any areas where it may already have been introduced. Biological life-history data and, where possible, genetic data in the form of protein electrophoretic analysis, DNA fingerprinting etc., should be collected.
3.2.2 When the time comes to stock out in the wild or in cages, after quarantine, utilize only non-breeding or sterile individuals if possible.
3.2.3 Protect and preserve, at the earliest possible stage, the broad genetic diversity present within the indigenous aquatic organisms most threatened by an importation, by establishing “reserves” (areas where introductions or transfers are forbidden), by artificially maintaining unselected populations or by cryopreservation of gametes or embryos.
3.2.4 Ensure that stock to be introduced for stock rehabilitation purposes or sea ranching is selected from an environmentally similar area (ideally geographically adjacent) and that it is selected to occupy a niche not already filled by an indigenous species or to fill a niche no longer filled because of the extinction of a stock.
3.2.5 Introduce small numbers, under closely controlled conditions, in stages, in order to monitor genetic effects on indigenous species. In this manner, an introduction could be curtailed immediately if adverse effects appeared.
3.2.6 Evaluate thoroughly, before introduction to enclosures or to areas for sea ranching, any genetically engineered aquatic organisms, to determine their possible effects on indigenous species. New genetic methods are being exploited in aquaculture to produce fish or other aquatic organisms with modified genomes (e.g., by selection, polyploidy, gynogenesis, gene transfers etc.). Although this can confer considerable advantage in aquaculture, it could have a detrimental effect on natural populations through competition or because of introgression of the novel genes into wild genomes.
3.2.7 Ensure that national legislation to control movements (introductions or transfers) are constantly updated to cover new technical breakthroughs. For example, recent developments in methods for the storage and transport of chilled and frozen gametes and embryos can facilitate introductions and transfers and many national legislative controls do not cover movements of unfertilized gametes.
3.3.1 Each country should prepare a list of species eligible for introduction or transfer (possibly done by the national committee or working group set up to coordinate introductions). Experience obtained from previous introductions should be used to update these lists annually, and they should be made available to inspection staff involved in actual examination and certification of import.
3.3.2 A list of known parasites and diseases of eligible species should also be compiled and periodically updated. The list would be used by inspection staff when examining certification papers and actual shipments as they arrive in the country.
3.3.3 Once approval for an importation (for quarantine and testing) has been given, the agency or group making the request, must obtain from the government of the country from which the species originates, a certificate (permit) confirming the origin of the stock, stage to be exported, disease history (as far as known), parasite/predator history, and other specifics as may be required. If the exporting country cannot satisfy the health requirements of the importing country, quarantine is the minimum requirement.
3.3.4 Inspections aimed at satisfying disease or other certificate requirements of 3.3.3 must be carried out by qualified personnel duly authorized by the exporting and importing countries.
3.3.5 Inspection procedures upon arrival of the introduced species at a quarantine site or other release sites should include the destruction or sterilization of all water, packing materials, containers, or other associated shipping materials.
3.3.6 Coordination between the proponent of an introduction or transfer (could be private or government) and the national agency monitoring importation is very important throughout an initial probationary period. A contact from the agency approving the proposal should be named to liaise with the proponent.
3.3.7 Upon completion of initial examination by inspectors of the importing country, the shipment, depending on the conditions imposed, should be released to quarantine, containment or directly for culture.
3.3.8 Quarantine facilities, where required, should be approved and regularly inspected by competent government specialists to ensure effectiveness.
3.3.9 The microscopic and macroscopic examination required while specimens are in quarantine makes it essential that proponents provide sufficient numbers of individuals for introduction and testing. The numbers required and the schedule for testing would be specified by the agency which approves import and would be dependent on species and stage at introduction.
Introduced or transferred aquatic organisms which are placed in quarantine are, by definition, a potential health risk. The aim of quarantine is to establish that they are either free of prescribed pathogens and pests or if not, that their progeny may be acceptable if they are proven pathogen- and pest-free. Because aquatic organisms may covertly carry pathogens without showing overt signs of clinical disease, they must in most cases be held in quarantine for life and be subject to repeated tests to establish their pathogen-free status. If they are established as pathogen-free, the F1 generation may be released. If the F0 generation is not pathogen- and pest-free and they are not destroyed but kept for breeding, then it may be necessary to quarantine the F1 generation for life, demonstrate the F1 generation is free from pathogens and pests and then use the F2 generation for release.
3.4.1 Introductions, whether as gametes or fertilized eggs for fish (preferred) or as some other stage for molluscs or marine plants, should be disinfected upon arrival at the quarantine unit (even though an approval certificate is supplied). If young fish are being imported, they should be treated by prophylactic bath. As stated under inspection and certification procedures, all materials in contact with the import during shipment should be destroyed or sterilized and not allowed to enter the holding system area of the quarantine unit.
Acclimation of eggs, larvae, adult organisms etc., to environmental conditions, such as temperature at the quarantine station, should be done in a manner which prevents, as far as possible, any contact between transport and final holding media.
3.4.2 It is recommended that intake waters be sterilized or disinfected. Sterilization means killing all life forms in the water supply. Disinfection means using techniques which will kill all the prescribed pathogens. Spring, ground, artesian, and well waters which have no flora or fauna in them prior to entry to the quarantine unit are best and require no treatment. If surface waters are used, there is a risk that native pathogens and pests may cause disease outbreaks in the quarantine unit causing consequent difficulties in deciding whether the pathogen is native to the water supply or was imported with the introduction.
3.4.3 The quality of water used in the quarantine unit should be monitored at regular intervals to ensure that any mortality in the quarantine population is not due to environmental conditions but rather to disease agents.
3.4.4 The cause of mortality in all animals in quarantine should be investigated and a written report should be prepared. All reports must be submitted to the regulatory authority who may undertake further investigations.
3.4.5 Disposal of solid wastes (faeces, surplus food, settled solids) and dead organisms must be conducted by an approved method, e.g., sterilized such that potential pathogens and pests cannot escape the quarantine unit by this route.
3.4.6 When recirculation of water is practised, both assessment and control of water quality must be carried out.
3.4.7 Records of operating conditions and procedures must be kept and made available for inspection by the regulatory authority on request.
3.4.8 If more than one stock (or species) is kept in the quarantine unit each must be kept in a self-contained compartment and precautionary measures instituted to ensure that staff cannot cause transmission of pathogens or pests between different stocks.
3.4.9 No equipment should enter or leave the quarantine unit without disinfection. If several species or stocks are kept in quarantine in separated modules, separate equipment must be available for each group.
3.4.10 Personnel operating the quarantine unit must be supervised by staff qualified to ensure all biological and operating concerns are appropriately addressed.
3.4.11 Personnel should enter and leave a quarantine unit through a disinfection station (footbath, showers) which should be regularly serviced to guarantee continued effectiveness.
3.4.12 Personnel operating a quarantine unit should not visit other aquaculture establishments on the same day.
3.4.13 The quarantine station should have adjacent, but physically isolated, laboratory facilities for inspection and preparation of material for pathology tests. Physical separation from the quarantine unit should help prevent accidental contact with quarantined species.
3.4.14 Should outbreaks of disease or pests occur while a species is in quarantine, a range of common treatment procedures should be immediately available. However, while these procedures may be successful in killing specific pathogens or removing specific parasites, they should not be viewed as an effective means of destroying all organisms carried by introduced species.
3.4.15 Should the quarantine unit suffer a disease outbreak that cannot be controlled, the diseased stocks must be destroyed and disposed of after sterilization in an approved manner, but not before notification of the appropriate government authority. The quarantine unit or particular module (including the biological filters if recycling system is used) must be disinfected prior to its reuse. It is advisable to operate dual systems to facilitate shutdown and sterilization procedures.
3.4.16 The design of the quarantine unit should minimize any risk that:
unauthorized persons gain access and cause the release of the aquatic organisms.
For purposes of this document, pathology is defined as, “the study of disease by scientific methods” (ICES Working Group on Pathology and Diseases of Marine Organisms). The objective of identifying diseases and parasites is to minimize or eliminate the introduction and distribution of organisms pathogenic to both native aquatic species and those being introduced. Steps required to prevent or minimize introduction of pathogenic organisms or parasites include:
3.5.1 An import permit should list prescribed diseases as outlined under inspection and certification (paragraph 3.3.2). The testing regime and results must be supplied with any shipment of aquatic animal or plant into a country. The permit should also certify that the shipment was examined and found free of all parasites.
3.5.2 Where feasible, the desired species should be imported as fertilized ova, as the range of disease agents that can be carried is much less than for later life history stages. Complete surface disinfection is more likely when treatment is administered at the egg stage.
3.5.3 Wherever possible the imported species, regardless of import stage, should come from a production facility or area which has been certified free of prescribed diseases over a two-year period.
3.5.4 Where an exporting country cannot prove it has the required capability for testing of stocks, the import must be considered a risk and be placed in quarantine upon arrival in the importing country. Appropriate testing must be carried out in quarantine.
3.5.5 Sampling for disease caused by viruses and bacteria or parasites while the species is in quarantine should be carried out under the supervision of a fish health officer or inspector employed by the government.
3.5.6 Sample size should be determined by reference to published techniques (examples, Ossiander and Wedemeyer 1973; Worlund and Taylor 1983), based on achieving a 95% probability of detecting a disease agent carrier in a lot with an assumed incidence of carriers.
3.5.7 Specific examinations should also be carried out on native species maintained in quarantine in same containers with imported species.
3.5.8 In the event of a positive identification of a disease, shipment of animals must be destroyed and disposed of in an appropriate manner to avoid spreading disease (see paragraph 3.4.15)
