|Please note: COABC's Aquaculture is currently not within the scope of the Canada Organic Standards, but members of the aquaculture industry, the Department of Fisheries and Oceans and Agriculture and Agri-Foods Canada are developing organic aquaculture standards. If you have comments (pro or con) with regards to the development of Organic Aquaculture Standards, please submit these to the forum . .|
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Wild salmon depend on natural photoperiod changes for maturation cues. In farmed fish, maturation may be similarly influenced. Photoperiod manipulation is necessary for fry in hatcheries where there would otherwise be no light. Existing organic aquaculture standards are inconsistent in permitting photoperiod manipulation to promote early smolting or maturation.
- Artificial light must not be used to manipulate smolting or maturation in production fish. Artificial light may only be used with fry and only to prolong the day length up to a maximum of 16 hours per day (Soil, UK/IFOAM)
- An artificial day length may not be longer than the year's longest natural day length for the species' range (Debio, Norway/KRAV, Sweden)
Indigenous and Exotic Species
There is an important distinction to be made between exotic and invasive species. "Exotic" species may be safely cultivated because they require continuous human intervention to persist. "Invasive" species are exotic species which have become established in a foreign environment, and independently persist and propagate to the detriment of that environment.
Organic production standards generally do not make a distinction between indigenous and exotic species. The vast majority of crops under organic management are, in fact, exotic species (only four U.S. crops are indigenous).
The question of whether Atlantic salmon is an invasive species in British Columbia is one that has received considerable attention by government, academia, and media. Over the past century there have been many intentional efforts to establish Atlantic salmon populations in various places throughout the world. This includes approximately 200 attempts involving the introduction of millions of Atlantic eggs and alevin to BC streams in the early 1900s. Cases of successful spawning of escaped Atlantics in rivers on Vancouver Island have been documented (Volpe et al., 2000). However, despite past efforts at introduction, no sea run population of Atlantic salmon has ever been established outside its natural home range. The Environmental Assessment Office's Salmon Aquaculture Review, which included an analysis of the ability of Atlantic salmon to colonize BC waters, concluded that the risk of Atlantic salmon colonization in BC is extremely low and that farmed escapees are not in any way compromising wild Pacific salmon stocks. Similar studies from other jurisdictions support this conclusion (The Net-pen Salmon Farming Industry in the Pacific Northwest and Review of potential impacts of Atlantic salmon culture on Puget Sound chinook salmon and Hood Canal summer-run chum salmon evolutionarily significant units.
It has been argued, however, that depressed levels of native species and subsequent niche availability may facilitate the establishment of Atlantic salmon in B.C. waters (Volpe et al., 2001).
The merits of cultivating local versus exotic species must be carefully considered. International standards invariably favour indigenous, locally adapted species:
- As stock for organic production, native species shall be preferred. The risk of escape or introduction of non-indigenous species in open waters shall be protected from (Naturland, Germany).
- Breeds should be chosen for their adaptation to the local environment (Soil, UK).
- Breeds that are adjusted to local conditions should preferably be used (Debio, Norway/KRAV, Sweden/BIO-GRO, New Zealand/ BIO SUISSE, Switzerland/IFOAM).
The academic community is divided over the risks of farming indigenous species. Many maintain that farming indigenous species presents greater risks to wild stocks because of the potential for escaped fish to interbreed with wild stocks, and the subsequent genetic dilution (Gausen and Moen, 1990; Fleming and Einum, 1997; Younston and Verspoor, 1998; Fleming et al., 2000; Fairgreave and Rust, 2003; Heath et al., 2003) - a factor that need only be considered for farmed Pacific salmon in British Columbia. This claim must be weighed against the fact that "salmon-enhancement programs", which annually release approximately five hundred million hatchery raised Pacific salmon into the wild, contribute incomparably more to this risk than do the low numbers of escaped farmed fish.
Genetically Modified Organisms
Genetically modified organisms are consistently disallowed in all organic production systems. IFOAM cites the following rationale:
IFOAM is opposed to genetic engineering in agriculture, in view of the unprecedented danger it represents for the entire biosphere and the particular economic and environmental risks it poses for organic producers. IFOAM believes that genetic engineering in agriculture causes, or may cause:
- Negative and irreversible environmental impacts
- Release of organisms which have never before existed in nature and which cannot be recalled
- Pollution of the gene-pool of cultivated crops, micro-organisms and animals
- Pollution of off-farm organisms
- Denial of free choice, both for farmers and consumers
- Violation of farmers' fundamental property rights and endangerment of their economic independence
- Practices which are incompatible with the principles of sustainable agriculture
- Unacceptable threats to human health
Triploid and Monosex Stocks
Most animals are naturally diploid, possessing two sets of chromosomes. Polyploid organisms are those that possess more than the usual chromosomal complement. Salmon are typically diploid, although triploidy does occur naturally at low levels of incidence as a result of temperature and pressure gradients in spawning beds. Triploid induction involves applying carefully timed heat or pressure shock to fertilized eggs, which results in the retention of the second polar body (a set of chromosomes normally lost during sexual reproduction).
There has been much interest expressed in the aquaculture industry in producing triploid farmed salmon because this technique greatly increases the level of biological (reproductive) containment. ) Other ecological effects of escaped triploid fish are under investigation (Sutterlin and Collier, 1991). Farmed indigenous salmon can and do escape and may breed with wild stocks. Triploid females, however, are sterile. Triploidization of mixed-sex populations of eggs is not recommended as male triploid salmonids do sexually mature and could possibly contribute to spawning activities resulting in lethal aneuploid offspring. It is thus desirable to have all-female, triploid stock.
Monosex, all-female stocks are produced over two generations by hormone treatment of first generation juveniles. The milt of the resultant sex-reversed males contains only X chromosomes and is used to produce all-female production stocks. To produce sex-reversed male brood stock hormone treatment is administered at the alevin stage just after hatching. A two hour treatment is given when 50% of the selected eggs intended to receive treatment have hatched, and a second treatment seven to ten days later when the remaining eggs have hatched. No further treatments are necessary. All treatments are prescribed by the attending veterinarian and the hormone is currently dispensed by MAFF. This hormone treatment is used only on brood stock, never on production fish, and constitutes less than 10% of the total developmental period (Cho., pers. comm.) Presently available and potential future methods of sex reversing and sterilizing salmonid fish have been described and/or reviewed by Devlin and Donaldson (1992), Hunter and Donaldson (1983) and Pepper (1991
Both artificially triploid and monosex stocks are consistently prohibited in international organic aquaculture standards. The polyploidy prohibition seems curious given that this condition does exist naturally. International organizations concerned with the development of aquaculture such as the United Nations Food and Agriculture Organization (FAO), the International Council for the Exploration of the Seas (ICES), and others concerned with the preservation of endangered species (NASCO) are encouraging the use of triploid salmon, which, according to European Union Directive 90/220/CEE of April 23, 1990 are not considered to be genetically modified (Komen et al.). United States Department of Agriculture (USDA) standards also state that natural processes found in the wild are acceptable in organic production.
Few consumer problems are anticipated with chromosome set manipulated fish as polyploidy has been long employed in plant agriculture (including in organic production). Triploid trout, which are considered identical to diploid fish in nutritional quality and consumer safety, have been marketed in Europe and North America. Moreover, the triploid condition does not seem to present any disadvantages to the trout farmer. In Atlantic salmon, however, the triploid condition affects both general performance and fitness. Research has identified a number of problems with triploid Atlantic salmon, including increased incidences of lower jaw abnormalities (Sutterlin et al, 1987; Jungalwalla, 1991; Hughes, 1992; King and Lee, 1993; and Lee and King, 1994), reduced survival during egg incubation and during marine grow-out (McGeachy et al, 1996), greater susceptibility to cataract formation (Wall and Richards, 1992) and diminished tolerance of chronic stress (Benfey, 1996). Triploid Chinook salmon reared at Yellow Island Aquaculture Limited on Vancouver Island have not shown developmental problems to date (Cho., pers. comm.). Fisheries and Oceans Canada is currently conducting research to determine rearing protocol that will resolve these problems.
Prohibition of monosex stocks follows a more clearly defined rationale since hormone treatment is regularly disallowed in organic production. The standard setting committee must decide if this restriction applies to brood stock, production fish, or both.
There appears to be no easy answer as to the permissibility of triploid, monosex stocks. Certainly, acceptance and wide-spread application of these techniques would mitigate a number of potential ecological risks associated with escaped, indigenous fish. On the other hand, such an allowance might restrict access of BC certified organic salmon to international markets where competing standards disallow these techniques.
Organic standards for terrestrial production systems require that producers feed livestock using certified organically produced feed. How to apply this principle to the diversity of herbivorous, piscivorous, and omnivorous diets of aquatic organisms is, without doubt, a major challenge in developing organic aquaculture standards. This is particularly true of piscivorous fish, which require a minimum percentage of fish meal and fish oil to satisfy their dietary needs. Fish meal and oil used in livestock feed are derived primarily from wild-capture systems, which generally cannot be organically certified. The fundamental requirement of organic livestock feed management is to provide a complete, balanced ration that closely conforms to the organisms natural dietary preference while remaining exclusively composed of allowable materials. Since there is currently no permissible alternative to including appropriate amounts of fish meal and fish oil in the diets of piscivorous fish, organic standards-setting committees have proposed a number of options to address this issue.
- allow a set percentage of fish meal and fish oil from wild-capture fisheries as a feed supplement in organic production. The amount allowable would dictate which fish species could feasibly be produced in an organic system.
- require that at least 50% of the fish meal and fish oil originate from trimmings or by-products of fish caught for human consumption and the remainder come from independently-certified sustainable fisheries that target stocks not used for human consumption. This is the option most widely used in existing standards. Some standards require the fisheries operate according to the 1995 FAO Code of Conduct for Responsible Fisheries. Others require third-party certification by the Marine Stewardship Council or a similar organization.
- Prohibit fish meal and fish oil from dedicated harvesting and manufacturing operations that are not independently certified as sustainable (Soil, UK).
Local sources of fisheries by-products should be investigated to determine the volume that could be diverted to an organic aquaculture sector. In the recognition that the availability of fish meal and oil will be a limiting factor for expansion of the aquaculture industry as a whole, research is under way to identify acceptable alternatives. In British Columbia, a government funded initiative is exploring the potential use of vegetable protein and oil as a fish meal replacement. Early results indicate that at least fifty percent of fish meal and fish oil can be replaced by vegetable-based products without compromising fish health or quality. The availability of alternative feeds may pose a number of benefits. Feed costs account for a considerable portion of overhead expenses in salmon aquaculture production. While new feeds containing a greater proportion of vegetable materials are currently similar in price to conventional feeds, higher demand and availability will result in lower feed costs. Concerns related to biomagnification (see below) would also be mitigated by a decrease in the content of fish meal and fish oil in feeds. The standards committee may consider encouraging the use of such feeds as they become commercially available.
There has been increasing awareness of the dangers to human health posed by dioxins, furans and polychlorinated biphenyls (PCBs) in the food chain. These environmental contaminants are the by-product of thermal processes occurring in the presence of chlorine. As persistent organic pollutants they are ubiquitous in nature and accumulate in the fat of animal species or in plant tissue. They become increasingly concentrated in animal species higher in the food chain through a process know as biomagnification. Approximately 90% of human exposure to these compounds results from the consumption of contaminated food.
As carnivores high in the food chain, farmed and wild salmon may consume and concentrate toxins that have accumulated in the fatty tissues of prey species. For farmed salmon, the main source of such toxins is fish feed that contains fish oil sourced from wild fish stocks.
In response to concerns that farmed salmon may contain unsafe levels of accumulated toxins, the Canadian Food Inspection Agency (CFIA) undertook a study in 1998/99 to determine the dioxin, furan and PCB levels in fish meal, fish feed and fish oils in the Canadian feed system. Based on the results of this study, CFIA scientists determined that dioxin-furan and PCB levels in fish feed and fish meal would not be expected to result in fish containing dioxin-furan or PCB levels above the Canadian Guidelines for Chemical Contaminants and Toxins in Fish and Fish Products (). In response to news reports in which the World Health Organization (WHO) was incorrectly cited as having lowered its recommended daily intake of salmon, the WHO issued a statement in 2001 clarifying that no such recommendation was ever made.
A small pilot study funded by the David Suzuki Foundation found higher levels of contaminants in farmed fish than in wild fish. The study claimed that contaminant levels were below the maximum intake levels recommended by the Canadian Food Inspection Agency, but higher than levels recommended by the World Health Organization based on consumption of one to three servings of farmed salmon per week (Easton et al., 2002). This study has been criticized by experts in the academic community as making unfounded claims based on inadequate data. A Swiss study subsequently reported lower levels of contaminants in farmed trout versus wild trout and whitefish (Zennegg et al., 2003). Additionally, local commercial organic compost producer, Helen Waugh, as quoted in the June, 2003 edition of Northern Aquaculture, claims to use only farmed fish carcasses in her compost in order to remain listed with the Organic Materials Review Institute (OMRI).
The health care management principles of organic agriculture are readily applicable to aquaculture systems. A preventive approach is preferred in health care management and should be exemplified through emphasis on providing suitable living conditions, feed ration, breed selection, and sanitation practices - all of which should contribute to pest and disease resistance. Designating allowable therapeutic agents is at the discretion of the standards-setting committee. Routine prophylactic treatment with synthetic drugs is prohibited in all organic standards, as are drugs and additives designed to artificially promote growth. Vaccines not containing GMOs are permitted.
ANTIBIOTICS IN SALMON AQUACULTURE
Salmon aquaculture development has been challenged with addressing a range of bacterial and viral fish diseases that have resulted in both production and animal welfare problems. These diseases have been known to pass both ways between farmed and wild stocks (Johnsen and Jensen, 1988; Brackett, 1991; McDaniel et al., 1994). In the early years of industry expansion, disease control focused mainly on the use of antimicrobial agents. As the industry matured, however, an effective range of vaccines was developed and the use of antibiotics has subsequently declined. Currently, in conventional salmon farm operations, the use of therapeutants averages 0.00131 mg/kg of product. Among the world's large protein-producing sectors, salmon farming uses the least antibiotics per kilogram of product (Waknitz, et al., 2003).
Antibiotics used in aquaculture are administered to fish in feed to treat disease - not, as in some other agricultural sectors, to promote growth. All antibiotics used in salmon aquaculture in British Columbia are administered by veterinary prescription. This is unique among BC's food-producing industries.
Health Canada (Bureau of Veterinary Drugs) licenses all veterinary drugs through the Food and Drugs Act. Provincially, the Ministry of Agriculture, Food and Fisheries (MAFF) monitors sales of veterinary drugs under the Pharmacists, Pharmacy Operation and Drug Scheduling Act and Medicated Feeds regulations. As all antibiotics used in salmon aquaculture (except in brood stock, which are not used for food) are administered through feed, monitoring the sale of medicated feeds provides the Ministry with information on 100% of the antibiotics administered to farmed food fish. MAFF maintains a database of this information for aquaculture.
There are currently four antibiotics licensed by Health Canada for use in salmon aquaculture, although other antibiotics may be prescribed by a veterinarian where deemed appropriate. On average, approximately 2.5% of all milled feeds are medicated each year.
All therapeutants have a prescribed withdrawal time - the period of time following treatment after which the fish are considered drug free and fit for consumption. Under the Aquaculture Regulation of the Fisheries Act, processed fish must have completed the withdrawal period as prescribed by a veterinarian and otherwise be in compliance with the standards of the Food and Drugs Act.
The Canadian Food Inspection Agency (CFIA) is responsible for monitoring food safety and audits all agricultural meat products for the presence of drug residues. This includes spot audits of processed farmed fish for the presence of such residues.
Given the comprehensive regulatory structure in place to monitor and control the use of antibiotics in salmon aquaculture, it appears that human health risks are negligible.
A comprehensive discussion of the issues that arise from antibiotic use in salmon aquaculture must also address any potential ecosystem-level effects of introducing medicated feed into the aquatic environment.
When fish are treated with medicated feed, a portion inevitably falls through the bottom of the cage and is deposited on the benthos. A further portion of the antibiotics consumed will also be excreted as faeces by the treated fish. The fate of antimicrobial agents in the marine environment will depend, in large part, on the characteristics of the site and, in particular, on currents and tidal flows. In sites with poor water turnover, antibiotic residues may accumulate in the sediments surrounding the farm, impact the composition of local microbial populations, or be ingested by fish and invertebrates in the vicinity of the farm.
Accumulation in sediments: Antibiotics such as oxytetracycline often adhere to particulate matter and, as a result, many studies have focused on the fate of these agents in sediments surrounding fish farms. Antimicrobial concentrations detected in sediments have ranged from 0.1-10.0 ppm (Coyne et al., 1994) to 189-285 ppm (Samuelsen et. al., 1992). Research regarding the longevity of antimicrobials in sediments beneath fish farms has indicated that the nature of the sediments play a major role in antimicrobial persistence (Alderman and Hastings, 1998). The half-life of oxytetracycline in marine sediments has been reported to vary from 9 to 419 days, with longer persistence directly related to anoxic conditions (Coyne et al., 1994; Bjorklund et al., 1990; Lai et al., 1995). Antimicrobials are generally only detectable in sediments below and directly downstream of the treated cage (Kerry et al., 1996). Overall, the literature suggests that antibiotic residues do accumulate in sediments beneath fish farms during and following treatment, and that these residues are degraded over time at rates dependent on sediment chemistry.
Bacterial resistance: The use of antibiotics in fish farms has been shown to coincide with an increased frequency of resistant microflora and fish pathogens in the sediments beneath the farms (Samuelsen et al., 1992; Bjorklund et al., 1991; Capone et al., 1996; Kerry et al., 1996; Herwig et al., 1997). The highest numbers of resistant bacteria are found nearest the net cages, with densities declining in orders of magnitude with increasing distance from the cage (Herwig et al., 1997). An Irish study on the use of oxytetracycline in salmon farms showed no significant increase or a transitory increase in resistance beneath the farms sampled (Kerry et al., 1994). In Norway, oxytetracycline resistance was reported in bacteria beneath an abandoned farm site in frequencies remarkably similar to those found in samples of Irish sites free of fish farm effluent, suggesting that the operation of fish farms had had a negligible long-term impact on sediment microfloral assemblages (Husewag and Lunestad, 1995; Smith et al., 1995). It should also be considered that none of the published studies have properly identified the "resistant organisms" that have been isolated. Alderman and Hastings (1998) suggest that the large proportion of "resistance" identified may actually represent the temporary expansion of organisms that are naturally resistant to the antibiotics concerned into the ecological niches left by those organisms susceptible to the antibiotic used. Also important to account for are the impacts of certain physicochemical factors on the bioactivity of antimicrobials in the aquatic environment. Activity may be significantly reduced at lower water temperatures and in the presence of sea water cations (Barnes et al., 1995; Burka et al., 1997) or marine sediments (Smith et al., 1996). For example, oxytetracycline complexes with magnesium in sea water, resulting in only 5% of the antibiotic existing in free, bioactive form (Lunestad and Goksoyr, 1990). As a result, antibiotic residues in sediments may be biologically inactive. In summary, antibiotic use in fish farms inevitably alters microbial populations in sediments beneath and directly downstream of the treated net-pens, but these shifts in population structure are transient as is the presence and activity of the residues.
Bacterial resistance and human health: Concern has been voiced that antibiotic resistance occurring near fish farms may potentially pose a risk to human health. This is considered an unlikely scenario, however, because the various bacteria responsible for fish diseases in the northern environment are adapted to cold-blooded hosts and low water temperature and, as such, are rarely human pathogens (Alderman and Hastings, 1998).
Ingestion by non-target animals: A number of studies have also documented the presence of antibiotic residues in fish, shellfish, and crustaceans in the vicinity of fish farms. Researchers in Norway found that wild fish caught near farms contained drug residues in their muscle tissues (Ervik et al., 1994). A similar study found antibiotic residues in exploitable wild fish, shellfish, and crustaceans (Samuelsen et al., 1992). Capone et al., (1996) found no more than trace oxytetracycline residues (about 0.1 g g-1) in oysters (Crassostrea gigas) or Dungeness crab (Cancer magister) collected under a farm, but about half the red rock crab (Cancer productus) collected under the cages during and within 12 days of oxytetracycline treatment contained oxytetracycline in meat at concentrations of 0.8 to 3.8 g g-1. An Irish study found oxytetracycline residues in mussels directly beneath a salmon cage, but not in mussels collected at a distance of 20 m from the cage (Coyne et al., 1997). In summary, the available literature suggests that some animals in close proximity to net-pens treated with antibiotics will take up antibiotic residues. These residues will disappear over time following cessation of treatment.
Overall, the scientific literature suggests that antibiotic use in fish farms has local impacts on sediment flora, fish and invertebrates. However, beyond the farms periphery the tremendous dilution factors involved would suggest that broader ecosystem effects and human health concerns are minimal (Alderman and Hastings, 1998).
Antibiotics in Organic Production Systems
In many terrestrial livestock production systems, organic standards now ban the use of antibiotics (the COABC allows antibiotic use in bees with a withdrawal period of one season and in poultry with a minimum withdrawal period of three months, but disallows their use in all other slaughter stock). While livestock producers originally believed this would not be feasible, the development of alternative farming practices has made it possible to successfully preclude the use of antibiotics - thus "raising the bar" and enabling producers to clearly differentiate their product from conventional products and to obtain a price premium.
It must be said, however, that aquaculture presents a number of unique challenges in treating sick animals. Aquatic organisms must typically be treated as a group, whereas terrestrial animals are easily isolated and treated individually. Treatment options are also limited for aquatic animals - usually to medicated baths or feed. The implications for an aquaculture producer are that, even if only a small percentage of the stock becomes diseased, the entire stock must be treated. A zero tolerance standard for antibiotic use would perhaps present potential organic salmon producers with an unacceptably high level of risk since a single disease incident in the production cycle would preclude organic certification for the entire stock.
As in any organic production system, antibiotics must not be withheld in order to maintain organic status when their use becomes necessary. Whether organisms treated with antibiotics can retain their organic status is ultimately at the discretion of the standards review committee. Many standards (IFOAM, Naturland, Soil Assoc., Debio/Krav, ERNTE, Bio-Suisse, NOFA) require that a doubling of the withdrawal period be observed before the animals can be harvested and sold as certified organic product. SGS requires a tripling of the withdrawal period. Others (Bio-Gro, NASAA, BFI) require that any animals treated with antibiotics be removed from the organic production stream and be sold as conventional product. YIAL has proposed a similar standard.
Sea lice are crustacean ectoparasites that feed on the mucous and skin of host fish. They affect salmon in a variety of ways, mainly by reducing fish growth, causing loss of scales (which leaves the fish open to secondary infections) and damage to the flesh (which reduces marketability). High parasites loads may also result in fish mortality. Sea lice commonly infect both wild stocks and farmed fish.
Concern has been raised that salmon farms act as reservoirs for sea lice, which may infect wild stocks as they migrate past the farms. Several studies in Ireland, Norway, and Scotland support this contention (Tully et al. 1993; Birkeland, 1996; Pike and Wadsworth, 1999; Tully et al, 1999; Bjorn et al, 2001; Bjorn and Finstad, 2002). To date, there are no empirical data linking the 2002 decline in Broughton Archipelago pink salmon with the salmon farms in that area. Preliminary investigations by Alexandra Morton suggest elevated levels of sea-lice infection of wild pink salmon near farms in this area. The provincial government and DFO are currently monitoring sea lice on wild salmon and monitoring/managing sea lice on farmed salmon.
Globally, a variety of treatments for sea lice exist. These include bath or in-feed treatments using pyrethroid/pyrethrins, organophosphates, avermectins, benzonphenyl ureas, or hydrogen peroxide. Research suggests that at least some of these chemicals pose varying degrees of environmental risk, including toxicity to non-target aquatic organisms (McLeese et al., 1980; Mian and Mulla, 1992; Siegfried, 1993; Davies et al., 1998; Ernst et al, 2001).
The B.C. Ministry of Agriculture, Food and Fisheries monitors the use of antibiotics and other treatments prescribed by veterinarians in the control of diseases and pests such as sea lice. Ivermectin and emamectin benzoate (SLICE) are currently the only treatments prescribed for sea lice in B.C. and are administered in feed. Ivermectin use has declined since the advent of SLICE. Studies suggest ivermectin may present ecological risks in marine ecosystems (Black, et al., 1997; Davies et al., 1998; Collier and Pinn, 1998). American lobster force-fed high doses of emamectin benzoate displayed premature molting (Waddy et al., 2002). However, crustaceans are not known to eat fish feed pellets (whether containing low levels of emamectin or not) and, in the case that they did, would need to consume enormous quantities to match the concentrations used in the laboratory study. Fish treated for sea lice with these chemicals can not be harvested for food within a specified withdrawal time.
Most farmed salmon-producing jurisdictions (including B.C.) now recognize the value of an integrated approach to lice management that includes:
- regular monitoring of lice numbers
- coordinated treatments between farms in the same area
- single generation sites
- fallowing of management areas to break lice cycles
- treatment of lice in spring when lice numbers are low
According to organic principles, an organic salmon standard must simultaneously prohibit the release of detrimental materials into the environment, ensure the health of farmed fish, and minimize the risk of disease transmission between farmed and wild fish. Low stocking densities, stock selection, and optimal site location may effectively mitigate problems of sea lice infestation (MacKinnon, 1997). Low stock densities are desirable because, as with many other disease or parasitic infections, infestation levels are host-density dependent. Parasite loading is also reduced in areas of high water flow. MacKinnon (unpublished data) also found that sites with higher water temperatures and stocking densities had greater levels of sea lice. Yellow Island Aquaculture Limited attributes their 18-year success in avoiding lice infestations in their chinook salmon to a combination of low stocking density and site characteristics such as high water flow (Cho, pers. comm.).
L. salmonis is a species of sea lice specific to salmonids and affects Atlantic salmon most severely. In the Pacific northwest, Caligus clemensi is wide-spread but causes less damage. Eighty or more Caligus spp. Can be found on relatively healthy fish, but higher numbers can cause surface abrasion and stress to the fish (MacKinnon, 1997). Limited research suggests that salmon species may be differentially susceptible to sea lice infestation. Following experimental infection with sea lice, Atlantic salmon were more susceptible than chinook, and coho (Johnson and Albright, 1992; Fast et al., 2002). MacKinnon (1991) reported that Atlantic salmon have no immunoprotection against sea lice. Various fish farmers have also reported that they generally do not have lice problems in their chinook salmon stocks.
Soil Association standards for organic salmon production require farmed salmon be treated with hydrogen peroxide when lice levels exceed one ovigerous louse per 10 salmon - a very low level of infestation which ensures lice from farmed fish will not negatively impact wild stocks. It has been suggested that such a low threshold level is not appropriate for BC farmed fish given that wild populations have a much higher level of infection (Constantine, pers. comm.). Salt flushes are also permitted. However, studies of the efficacy of hydrogen peroxide in lice removal from salmon suggest that this compound is less successful in removing attached larvae than adult and pre-adult lice, and that the lice may potentially recover and re-infect the fish (Thomasses, 1993; Johnson et al., 1993). Also, hydrogen peroxide is increasingly toxic to salmon at higher temperature, concentration, and exposure time (Davies et al., 1998). Some argue against this mode of treatment on animal welfare grounds. Use of "cleaner-fish" such as wrasse, which feed on lice, is also being encouraged on European fish farms, although issues of animal welfare and protection of wrasse stocks have been raised. Research into potential indigenous species that might similarly act as lice cleaners should be encouraged.
Basic Living Conditions
The techniques for maintenance of proper living conditions must be governed by the physiological and ethological needs of the organisms in question while simultaneously maintaining the health of the aquatic ecosystem. A primary concern is the stocking densities of farmed fish. Stock densities should be as close as possible to natural conditions. Some species of fish become aggressive if densities are too low. Others (such as salmon) require sufficient space to allow for natural schooling to occur. Conventional net-pen salmon farms typically stock fish at 10-12 kg/m3 for Chinook and 16 kg/m3 for Atlantic salmon. The majority of organic aquaculture standards cap density at 10 kg/m3- for Atlantic salmon. It has been suggested by sonar surveys that Pacific salmon naturally school at densities of 5 kg/m3 or less (Cho, pers. comm.).
Concerns have been voiced regarding whether raising farmed fish in net pens is acceptable in an organic system, particularly if the species is migratory. Again, comparisons can be drawn with terrestrial livestock production. Arguably, keeping fish in large net pens is no different than raising sheep and cattle in fenced enclosures. Net cages are generally large (10x10x10 m) and subject to high water flow. Furthermore, farmed salmon are harvested before reaching maturity - which is the only time when the migratory instinct is significant.
Separation of organically and conventionally managed animals must also be ensured if both are raised or handled at the same facility.
Maintenance of the integrity of the soil is central to organic agriculture. For aquaculture, it is the quality of the water that must be ensured - both in terms of its purity as an input and its freedom from pollution as an output. A key consideration for the maintenance of water quality in aquaculture production is the introduction of excess feed and faeces into the aquatic ecosystem. While organic standards favour production systems that contain and recycle the nutrients they produce, a truly closed system is rarely possible - even in terrestrial production systems. The critical question becomes whether the aquatic ecosystem has the capacity to naturally cycle these nutrients. As such, the potential for environmental impacts is site-specific.
The question as to whether nutrient inputs from salmon farms into marine ecosystems may contribute to harmful algal blooms (HABs) has been well addressed in the scientific literature (Brooks and Mahnken, 2003). In most marine environments, nitrogen is the limiting nutrient. In the Pacific Northwest, however, primary production is generally light limited. HABS may occur in shallow, poorly flushed bays, where salinity and temperature-induced stratification sometimes results in a stable water column. These conditions occasionally occur in spring or summer, leading to significant plankton blooms. Salmon farm effluent in such areas could potentially contribute to these blooms. However, shallow, poorly flushed locations are generally considered unsuitable as farm sites. Most farms are situated in areas where currents generally average 4-12 cm/s (Brooks, 2001). Algal cells divide every 1-2 days at water temperatures of 10-15°C under optimal conditions (Brooks, 2000). Algal populations require eight or nine cell generations to reach "bloom" numbers. Even at a current speed of 2 cm/s, phytoplankton would move 14 km from the location at which the farm nutrients were added in the 8-16 days required for this number of cell generations. Given that nitrogen contributions from salmon farms are generally undetectable at 30m downstream of the site, it is difficult to imagine that this nutrient input could cause HABs, even if the water body was nutrient limited (Brooks and Mahnken, 2003). Various others have also examined phytoplankton production and blooms in the Pacific Northwest and found that salmon farms had little or no effect on ambient levels of either nutrients or phytoplankton density (Parsons et al., 1990; Pridmore and Rutherford, 1992; Taylor, 1993; Taylor and Horner, 1994).
Research has shown that in some cases fish faeces may accumulate on the sea floor beneath net-pens. Excessive waste can result in the development of anoxic conditions and a decline in biodiversity in the benthos. These conditions have been found to have measurable effects up to five years following the cessation of farm operations, before the sea bed returns to baseline conditions (Findlay and Watling, 1997; Janowicz and Ross, 2001; Pohle et. al. 2001). Accumulation of organic material under farms can extend to distances of 145-205 m. The magnitude of effects is correlated with water depth and current speed at the farm site. Decreases in both the abundance and diversity of macrofauna are sometimes seen in under farms located in areas with slow currents and fine-grained sediments. Conversely, macrobenthic production can be considerably enhanced where currents are fast and rock, cobble, gravel, or shell hash sediments prevail (Brooks and Mahnken, 2003).
New waste management regulations and criteria to assess environmental impacts for finfish aquaculture have recently been created in British Columbia. These performance based standards use 1300 umol sulphide concentrations in sediments beneath salmon farms as a threshold level for remediation. Many taxa can be excluded from sediment with sulphide concentrations less than 200-300 umol. The number of macro benthic taxa has been shown to be halved at approximately 1000 umol, but macrobenthic biomass appears stable at 4750 umol (Brooks and Mahnken, 2003).
In all cases studied, benthic impacts from salmon farms are ephemeral, and remediation occurs naturally without intervention during fallowing periods or following cessation of the operation (Brooks and Mahnken, 2003).
The standards-setting committee must determine whether the B.C. regulations satisfy waste management concerns or if further measures are desirable. It must also be noted that establishing lower stocking density standards will concurrently reduce effluent production and the associated benthic impacts. The standards-setting committee might require that excess faeces be collected, where appropriate, and used in agriculture.
In the past, accumulation of feed pellets in the benthos was also a concern for the aquaculture industry. However, improvements in technology and feed management practices have subsequently greatly reduced feed wastage. Feed wastage is currently estimated at less then five percent (Findlay and Watling, 1994).
Research is currently being conducted to assess the feasibility of producing shellfish and seaweed in the vicinity of net pen farms to uptake excess nutrients (Chopin et al., 2001; Chopin and Bastarache, 2002). Termed "polyculture" this concept offers some interesting possibilities in terms of increasing nutrient cycling within an aquaculture operation. Other researchers are investigating the possibility of using rotifers to digest fish faeces and subsequently using the rotifers as food for cultured shrimp. Polyculture should be encouraged in organic aquaculture standards to close nutrient cycles and enhance productivity.
Above all else, site selection can be a critical factor in determining an operations impact on local ecosystem processes. Favouring areas of high current flow may prevent sediment build-up, parasite loading, and enhance ambient water quality (Merceron et al., 2000). The Soil Association standards require a minimum tidal flush rate of 5-10 cm/sec at organic production sites and that the current speed should exceed one body length/sec at some stage of the tidal cycle. Additionally, their standards require that each farm develop an environmental management plan that defines
- the environmental loading of the site and its impact on the surrounding area, with appropriate controls or reductions.
- measures to prevent fish escapes.
The reddish-pink colour of wild salmon flesh is due to the presence of a carotenoid pigment called astaxanthin. This naturally occurring pigment is derived from marine algae. The algae are consumed by crustaceans which, in turn, form an important part of a wild salmon's diet. Research suggests that astaxanthin fulfils a number of essential biological functions for salmon, influencing reproduction, vision, immune response, and protection against oxidation of essential polyunsaturated fatty acids (Christiansen et al., 1995; Bell et al., 2000). As such, it is necessary to ensure that farmed salmon receive appropriate amounts of this carotenoid in their diet.
Conventional salmon farming operations include astaxanthin as a dietary supplement in the feed, both to promote optimal fish health and to ensure that the flesh colour is palatable to consumers. It is added to feed at a level of approximately 2.5 ounces per ton. Astaxanthin can be manufactured by chemical synthesis in much the same way vitamins are produced for human consumption. This synthetic form is commonly used on B.C. fish farms.
Because organic production standards usually preclude the use of synthesized materials as supplements, natural sources of astaxanthin have been required in the existing organic finfish aquaculture standards. Astaxanthin, found naturally in the yeast Phaffia rhodozyma and the microalgae Haematococcus pluvalis, is commercially available. Alternately, the use of shrimp shell as a by-product from wild-caught or certified farmed shellfish processing may be used for natural pigmentation, although it is suggested that this adds to the ash content (and subsequent waste) of the feed (Cho., pers. comm.).
Fish farms often attract predators such as river otters, seals, sea lions, and birds. Early attempts at predator exclusion via surrounding the net-pens with predator nets were largely ineffectual. The walkways surrounding the pens from which the nets were hung were fairly narrow, and the predator nets were not sufficiently weighted to prevent predators from simply pushing the predator nets in against the net-pens. Farmers subsequently suffered high stock losses. Some resorted to the use of acoustic deterrents but this practice was abandoned due to ecological concerns. Others have resorted to shooting predators. None of the above practices conform to the requirements of an organic production system. New net-pen technology, which employs wide external walkways and heavily weighted predator nets, appears to successfully exclude predators. Organic standards should encourage the use of such systems and set guidelines for acceptable predator control practices.
In marine ecosystems, surface area is often a limiting factor for invertebrate recruitment. Net-pen structures provide ideal settling conditions for a diversity of marine invertebrates. Often, the sheer mass of organisms is sufficient to sink the affected structure. This so-called "bio-fouling" can also decrease water flow through the nets and necessitates that such organisms be periodically removed. Fish farms typically use nets and structures treated with anti-fouling agents (usually copper-based paints) to deter settlement. However, many of these agents contain environmental toxins, and concerns that heavy metals may enter and accumulate in the marine environment have been raised in the scientific literature. Organic aquaculture standards consistently disallow the use of copper-based and other toxic anti-fouling agents. Mechanical anti-fouling measures such as pressure-spray and drum removal of fouling organisms are preferred. It must be ensured that debris from net cleaning does not adversely affect the benthos.
According to organic principles, stress and suffering of the organism must be minimized during the slaughtering process. Several practices are currently employed for slaughter but existing organic aquaculture standards are not consistent in identifying preferred methods. Typically, slaughter involves rendering the fish unconscious followed by exsanguination via severing the gill arches. Fish may be rendered insensate by mechanical stunning, electrocution, carbon dioxide bath, ice slurry, suffocation, or clove oil. Mechanical stunning (by a blow to the head) appears to be favoured in all existing standards, while the use of ice slurry or carbon dioxide is inconsistently disallowed. Concern exists that the use of carbon dioxide or ice may cause undue stress and is inhumane. Suffocation (leaving fish on ice to die) is prohibited.
The standards-setting committee may consider requiring containment of blood-water from processing operations to minimize risks of disease transfer.
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- To produce food of high quality in sufficient quantity.
- To interact in a constructive and life-enhancing way with natural systems and cycles.
- To consider the wider social and ecological impact of the organic production and processing system.
- To encourage and enhance biological cycles with the farming systems, involving microorganisms, soil flora and fauna, plants and animals.
- To develop a valuable and sustainable aquatic ecosystem.
- To maintain and increase long term fertility of soils.
- To maintain the genetic diversity of the production system and its surroundings, including the protection of plant and wildlife habitats.
- To promote the healthy use and proper care of water, water resources, and all life therein.
- To use, as far as possible, renewable resources in locally organized production systems.
- To create a harmonious balance between crop production and animal husbandry.
- To give all livestock conditions of life with due consideration for the basic aspects of their innate behaviour.
- To minimize all forms of pollution.
- To process organic products using renewable resources.
- To produce fully biodegradable organic products.
- To produce textiles which are long lasting and of good quality.
- To allow everyone involved in organic production and processing a quality of life which meets their basic needs and allows an adequate return and satisfaction from their work, including a safe working environment.
- To progress toward an entire production, processing, and distribution chain which is both socially just and ecologically responsible.
- International Federation of Organic Agriculture Movement
- Naturland (Germany)
- Soil Association (UK)
- Debio (Norway)
- KRAV (Sweden)
- NASAA (Austria)
- ERNTE (Austria)
- ISEES (Workshop at U of Minnesota - based on IFOAM)
- BioSuisse (Switzerland)
- SGS (Netherlands)
- Marine Stewardship Council (London-based - environmental standard for sustainable and well-managed fisheries)
Appendix C. Articles referring to organic fish farming
- Organic salmon in the UK - Eating Wild & Organic Salmon
- UK producer of organic salmon - What is Organic Salmon?
- Wild at Heart - Organic farmed salmon in the UK
- Breaking into new markets with organic salmon - The Emergence of Balta Island Seafare onto the UK market
- Green Grow the Fishes - a Gloucestershire trout farm goes organic
- Trout farm granted organic status - First French organic trout farm
- Kerry trout farm nets top award - Irish trout farm gets Naturland certification
- The Welfare of Intensively Farmed Fish - A report for Compassion in World Farming Trust
Appendix D. Producers of organic fish
Clearwater Crayfish, New Zealand
Fiordo Blanco, Chile
Ummera Irish Smoked Organic Salmon, UK
Balta Island Seafare, Scotland
Kinvara Smoked Salmon, Ireland
Graig Farm Organics, Wales
Graig Farm Organics, Wales
Purely Organic, England
Hawkshead Trout Farm, England
Trafalgar Fisheries, England
List of Farrms without Web Sites, UK (Hawkshead, above, has one)
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