RMS FOR farmed fish

1.1

​Fish must be stocked at densities that support good fish welfare, determined by species and life stage, and by the need to achieve good water quality and good health status, and to meet behavioral and physiological requirements. Maximum stocking densities for some species are set out in Table 1. Note that reduced stocking densities may be required when water parameters are sub-optimal in parts of the cage/tank.

Species, life stage

Maximum stocking density: kg/m3

Atlantic salmon, seawater phase

10

Pangasius

10

Gilthead sea bream, seawater phase

15

European seabass, seawater phase

15

Rainbow trout, on-growers

15

Tilapia

​See Resource 3 and 3b in the BII ESG Tilapia Toolkit. BII is a UK development finance institution.

2.1

​Water quality must be kept at optimal levels. Water quality parameters include temperature, conductivity, pH, oxygen concentration, turbidity, total dissolved solids, salinity, carbon dioxide and nitrogenous compounds (such as ammonia, nitrite and nitrate) concentration. Minimum or maximum levels for certain water quality parameters are set out in Table 2.

2.2

Water quality parameters must be monitored daily at various depths and maintained in an optimal range for the species. Avoid rapid changes in water quality parameters. Extreme temperatures and pH values (pH is a measure of the acidity of water) must be prevented.

2.3

​The flow rate of the water must be sufficient for removal of waste products and uneaten food and for fresh supply of oxygen.

2.4

Aquaculture sites should be carefully chosen or designed so as to ensure the adequate flow of clean water of suitable quality according to species’ requirements.

Species/life stage/size

Water quality parameter

Maximum or minimum level

Atlantic salmon

Temperature

​10-18°C but preferably 16°C-18°C

Atlantic salmon

Oxygen concentration

70-85%

Atlantic salmon

pH

​7-8.5

Rainbow trout

Temperature

Maximum 16°C

Minimum 1°C

Rainbow trout

Oxygen concentration

>7mg/litre

Rainbow trout

pH

6.8-8.0

Sea bass

Temperature

Maximum 28°C

Minimum 8°C

Sea bream

Temperature

Maximum 30°C

Minimum 8°C

Pangasius

Temperature

27°C-30°C

Pangasius

Oxygen concentration

2.5-7.5mg/litre

Pangasius

pH

​6.5-9.5

3.1

​Fish must be kept in systems which meet their species-specific physical, behavioral and mental needs, including their requirements for shelter, substrate, appropriate water currents, light/dark periods, social grouping.

3.2

​Where effective environmental enrichments (specific to the species) are available, they must be provided. Enrichments should be backed by research showing suitability in meeting the needs of the species according to its behavior in the wild but adapted for captivity and appropriate to life stage.

4.1

​Fish must be fed on a diet that meets their nutritional needs according to the species and life stage.

4.2

Fishmeal and fish oil in feed must be minimized as much as possible but, where used, should be sourced from trimmings, i.e. parts of the fish discarded for human consumption.

4.3

The feeding method must minimize competition and aggression and ensure that all fish, including subordinates, have good access to feed. Insufficient amounts of feed, or feed in an unavailable form (e.g. excessively large pellets or feeding in a location where smaller fishes are outcompeted) can result in poor health and welfare. Fish should not be overfed as this can decrease welfare and uneaten feed can lead to poor water quality.

4.4

​Fasting periods should only be used if necessary and when advised by a veterinarian. Fasting periods should be minimized and for no longer than is required for fish welfare benefits (e.g. to reduce oxygen requirements and waste accumulation in the water) and should not exceed 72 hours for each fish. Feed must not be withdrawn to adapt production levels to the market situation. Records need to be kept about why, when, and for how long feed was withheld from fish.

5.1

​Handling should be kept to a minimum, but when absolutely necessary, should be performed in such a way as to minimize stress.

5.2

​Fish must not be exposed to air or be out of the water unless absolutely necessary. If fish are removed from water they must be kept moist, must not be exposed to abrasive surfaces, and must be properly supported (i.e. never held by the tail only). Time out of water must never exceed 15 seconds, unless fish are anaesthetized.

5.3

​Fish should be moved in water where possible; e.g. using lined braille nets (that hold water), or by pumping fish in water. Pumping should minimize the risk of injury. Pumping height, pressure and speed, and the height from which fish fall when they emerge from the pump, should be adjusted to minimize injuries. Pumps should be free of sharp protrusions, kinks and bends. Fish should be monitored as they leave the pumping system for presence of fresh injuries and excessive exhaustion.

5.4

​Grading should be kept to a minimum and carried out in water.

5.5

​When crowding is necessary, it should be closely monitored for signs of stress and oxygenation should be provided prior to starting. Oxygen levels should be monitored continuously. If fish show signs of undue stress during crowding, immediate action must be taken, e.g. by increasing the volume of water available to them or by addition of supplementary oxygen. Any signs such as red water, free scales in the water, signs of skin/snout damage, hemorrhages on individual fish, vigorous escape attempts, ‘boiling’ appearance as fish struggle, and increase in swimming speeds after group swimming behavior breaks down should lead to immediate intervention. Crowding should only be carried out for a maximum of two hours with time for fish to recover between successive crowds. Fish should not be crowded more than twice in any week or 3 times in any month.

5.6

​Only anesthetics scientifically shown to be effective and non-aversive to the fish species should be used. Anesthetics are often needed for handling in order to minimize stress and physical damage.

6.1

​Effective steps must be taken to minimize injuries such as fin erosion, eye cataracts, skin injuries, loss of scales, skeletal deformities, and soft tissue anomalies. High mortality rates must be avoided.

6.2

Steps include:

• avoiding high stocking densities as these can result in injuries due to aggression or fish colliding with each other or abrasion from contact with cage netting or tank walls;

• ensuring that cage netting is smooth and non-abrasive to prevent injuries to the snout, fins and scales. Freshwater enclosures should be constructed of materials that minimize the potential for injuries;

• keeping crowding, handling and grading to a minimum and using best practice in these procedures;

• minimizing transport and ensuring good conditions during transport as poor conditions during transport, such as overcrowding and inadequate water quality, may result in irreparable damage to the fish, suffering and mortality;

• using feeding procedures that avoid competition and aggression.

6.3

​The factors involved in causing skeletal deformities must be addressed; these include inadequate nutrition, poor water quality and the use of excessive temperatures during incubation and early rearing in order to accelerate the development of the fish.

7.1

​Disease risk should be lowered as far as possible through good management and husbandry to reduce stress, e.g. low stocking densities, minimal handling, enriched environments.

7.2

​Parallel to good terrestrial farming practices, all aquaculture facilities should be registered with a suitably experienced veterinarian and have a veterinary health plan that includes health management procedures. This plan must be described in a manual, reviewed and approved by a fish health professional, and must include Better Management Practices, measures to prevent introduction of diseases, vaccinations, protocols for water quality management and health monitoring.

7.3

​Vaccinations should be used where the level of disease threat outweighs the negative effect on fish welfare of the vaccination procedure.

7.4

​Preventative measures against parasites such as sea lice should be foremost, but where antiparasitic treatments are required, they should be welfare-friendly, not causing pain or suffering, and minimizing handling stress. The following measures should not be used to tackle sea lice: hydrogen peroxide, in-feed or bath chemicals, the thermolicer and the hydrolicer.

7.5

​Cleaner fish – which are added to sea cages to eat lice off farmed salmon and trout - must not be used.

8.1

​Fish must not be selectively bred for fast growth or other production traits that result in health and/or welfare impairments.

8.2

​Genetic modification must not be used to breed farmed fish (e.g. transgenic, gene-edited or triploid fish).

8.3

​Hormones should not be used to make females develop as male (e.g. the use of methyltestosterone in tilapia) or to produce all female stocks.

8.4

​Broodstock must be anesthetized or humanely euthanized before stripping (i.e. extraction of sperm or eggs).

9.1

​Wild animals or birds should not be killed or otherwise harmed as part of anti-predator measures.

10.1

​Transport of live fish should be avoided where possible, but where absolutely necessary, transport time should be minimized.

10.2

​Fish should be inspected for fitness for transport prior to loading and should not be loaded if showing signs of disease, physical damage, or unusual behavior.

10.3

​Handling during loading and unloading should be minimized and be as gentle as possible. Fish should be maintained in water where possible and the time out of water otherwise reduced to an absolute minimum.

10.4

​Water quality (e.g. oxygen, carbon dioxide and ammonia levels, pH, temperature, salinity) should be appropriate for the species being transported and the method of transportation. Water quality and temperature parameters must be closely controlled and monitored, and stocking densities must be sufficiently low to avoid deterioration of water quality, especially accumulation of carbon dioxide and ammonia and depletion of oxygen. Additional oxygen (e.g. bottled oxygen) should be available in case of delays or a lapse in quality.

10.5

​The documentation accompanying the consignment (transport log) should include:

a) description of the consignment (e.g. date, time, and place of loading, species, biomass load);

b) description of the transport plan (e.g. route, water exchanges, expected time, date and place of arrival and unloading, receiver contact information).

10.6

​Transport vehicles must be well-designed to provide a safe environment to transfer fish and allow for appropriate welfare monitoring and inspection during transport.

11.1

​Fish must be stunned before slaughter using a non-aversive method that causes instantaneous unconsciousness lasting until death, or if unconsciousness is induced gradually, the process must be non-aversive.

11.2

In order to minimize the risk of consciousness being recovered, time elapsed between stunning and slaughter must be minimized. Concurrent methods of stunning and slaughter (e.g. electronarcosis leading congruently into electrocution) are preferred, but processes where death supervenes without significant risk of recovery of consciousness are acceptable.

11.3

All stunning and slaughter equipment must be calibrated appropriately for the specific fish to be processed (in terms of species, body size, and life stage), in order to achieve immediate and consistent loss of consciousness.

11.4

​Stunning and killing methods used must be effective for the species and age/size of fish being slaughtered.

11.5

Inhumane slaughter methods must not be used and must be rapidly phased out of the supply chain. Inhumane methods include exposing conscious fish to: ice slurry, carbon dioxide in water, asphyxiation in air, bleeding without prior stunning, gutting, bathing in salt or ammonia.

11.6

​Slaughter facilities and protocols must be designed, constructed and maintained to minimize stress and risk of injury to fish.