FishEthoBase is not designed for making recommendations that encourage to continue on old paths. Improvements of fish welfare would be very limited by the options already pre-set by the industry. FishEthoBase instead is mainly designed for recommending what should be considered before establishing or renovating a system. The range of recommendations for already constructed systems is limited by themselves, unfortunately.
The following recommendations do not intend to be a step-by-step manual to hatchery and farming. They are rather a collection of conclusions drawn from scientific findings challenging current farming standards and often taking the form of recommendations what not to do.
All recommendations are based on the studies we read (see «Findings» section). There is still a list of to-be-reviewed papers that potentially will improve the recommendations, let alone new studies to come.
When recommendations are based on a single paper, we added „More research needed“ in red to signal caution.
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Note of dissent:
The second author found no evidence to include the Whiteleg shrimp in a group of animals which have the capacity to suffer. Nevertheless there is a growing body of literature addressing this issue in crabs which show that crabs may feel pain, have a capacity to learn and have memory [F1]. The second author who is not a strict follower of the precautionary approach agreed to write these recommendations as if Whiteleg shrimp were indeed eligible for welfare protection, even though this is an approach that is not supported by the scientific literature currently available [F1].
The editor and the first author do not agree with the insular argument to consider animal welfare only in species for which the capacity to suffer has been proven. They insist upon a wider concept of animal welfare according to the Swiss law for animal protection which respects the dignity of living beings and their integrity independent of suffering.
It is obvious that the welfare of Whiteleg shrimp has not been a serious focus of research yet. And even if one sticks to the suffering paradigm it is probable enough that in Whiteleg shrimp, too, the capability to suffer will be proven some day [F1]. Thus the best recommendation to be made to shrimp farmers is to prepare for it ➝ FishEthoBase's understanding of fish welfare.
- Escapes: rear only in environments where it naturally occurs [F2] and prevent escapes. Else, escapees from shrimp farms have negative or at most unpredictable influences on the local ecosystem [F3]. Take care not to release individuals into the wild during pond cleaning (disease infections, water exchange, harvest) or floods. Prepare for sexual maturity (and thus spawning) from 6.5 months or 18-22 g on for males and 8.5 months or 21-28 g on for females [F4] and take measures against spawning into the wild.
3 Designing the (artificial) habitat
3.1 Substrate and/or shelter
- Substrate: in the wild, lives over sand and mud [F5]. For the most natural solution, provide sand and mud; alternatively, provide artificial sand preferably in yellow or red [F6], as these colours might also benefit growth – although this could also be an effect of better contrast to dark food pellets [F7]. Sediment layer on artificial substrate (aquamats, geotextile fabric, mosquito nets, polyethylene screens) increases growth by increasing periphyton and/or decreasing stocking density [F8].
- For substrate and occupation ➝ [R1].
- Shelter or cover:
- Cover: avoid complete cover of the tank or pond of a) post-larvae because of lower ingestion rate [F9] and b) juveniles because of lower growth and possibly lower survival [F10]. Further research needed.
- Vegetation: no ethology-based recommendation definable so far.
- Shelters: juveniles like to burrow during the day [F11]. Provide sand to allow for burrowing (➝ Substrate); alternatively, provide artificial shelters inside the system or outside.
- Photoperiod: given the distribution [F2] [F12], natural photoperiod is 10-14 hours, depending on the season. Provide access to natural (or at least simulated) photoperiod and daylight. Keeping Whiteleg shrimp under 24 hours scotoperiod decreases growth and might increase mortality [F10]. Further research needed.
- Light intensity: although lighting regimes like "1,500 lux light intensity on six consecutive days and abrupt change to 60 lux for two days; repeat the cycle" or "24 hours 10,000 lux" [F10] yield growth in juveniles, refrain from it, as we have not found studies reporting possible long-term effects on welfare ➝ FishEthoBase's understanding of fish welfare. Also, long photoperiod could contribute to growth rather because of chlorophyll-a serving as additional food source; light alone does not seem sufficient to influence growth [F10]. Further research needed.
In juveniles, under laboratory conditions, tendency of best growth under metal halide lamp emitting 2,500 lux shining only day [F10]. This regime resulted in the highest free astaxanthin concentration responsible for body colour, though, indicating that astaxanthin protects against damage from intense light [F13]. An incandescent light emitting 450 lux at most yielded low astaxanthin concentrations [F13], thereby seemingly most protective while preventing complete darkness. Further research needed.
- Light colour: no ethology-based recommendation definable so far.
- Resting period: allow Whiteleg shrimp a resting period at night or in the dark [F11].
3.3 Water parameters
- Temperature: no clear temperature preference, probably best kept at 26-30 °C [F14] [F15]. Above and below may mean lower survial [F16] and growth [F15]. Adjust temperature when you notice avoidance behaviour [F17] [F18]. Implemented in aquaculture, temperatures >22 °C demand excellent oxygen levels [F19] and a fine-tuned flow-through system to prevent bacterial load.
- Water velocity: no ethology-based recommendation definable so far.
- Oxygen: in the wild, oxygen level is at 0.7-13.3 mg/L [F19]. Further research needed. Maintain oxygen level that ensures welfare depending on temperature (➝ Temperature) and stocking density (➝ [R2]).
- Salinity: given the amphidromous migration type, natural salinity is at seawater level at hatching and again from juvenile stage on, brackish water level from post-larvae to sub-adult stage [F20] [F21]. Tolerance towards salinity has a bell-shaped curve, so do not expose newly-hatched or adult individuals to very low or very high salinities and to large salinity changes [F22]. Generally, prefer gradual (instead of abrupt) salinity change [F22] and avoid large salinity fluctuations of ±15‰ [F23]. The best salinity level for optimal growth depends on the acclimation salinity, water temperature, and water hardness [F23].
- pH: in the wild, ph is at 6.0-8.0 [F24]. For the most natural solution, maintain this range. Further research needed.
- Turbidity: no ethology-based recommendation definable so far.
3.4 Swimming space (distance, depth)
- Distance: no ethology-based recommendation definable so far. Provide enough space, bearing in mind the planned stocking density [R2].
- Depth range: in the wild, juveniles are found at <1 m, adults at 10-20 m [F25]. Provide at least 1 m for juveniles, ideally up to 20 m for adults, bearing in mind the planned stocking density [R2].
- Flight: no ethology-based recommendation definable so far.
- Temperature layers: in habitats with water layers with different temperatures, prepare for individuals migrating to layers with preferred temperatures [F14], and avoid crowding in these layers by providing enough space.
- Alternative species: omnivorous [F26], trophic level 2.0-3.0 [F27]. If you have not yet established a Whiteleg shrimp farm, you might consider to opt for a species that can be fed without or with even less fish meal and fish oil in order not to contribute to overfishing by your business [F28].
- Protein substitution: if you run a Whitleg shrimp farm already, try to substitute protein feed components that have so far been derived from wild fish catch, while taking care to provide your shrimps with a species-appropriate feed [F26]:
- Invite a feed mill and other shrimp farmers in your country to jointly establish a recycling syndicate that converts the remainders and the offcuts of fish processing into fish meal and fish oil, separating the production line corresponding to the species of origin in order to avoid cannibalism ➝ fair-fish farm directives (point 6).
- Inform yourself about commercially tested substitutes for fish meal and fish oil, like insect or worm meal or soy, with an appropriate amino and fatty acid spectrum.
Note of dissent:
The second author disagrees with this recommendation which to her opinion has to do with overfishing and ethics but not with animal welfare.
The editor and the first author adhere to the recommendation above because overfishing impairs the marine food chain and consequently the living of marine animals, thus animal welfare, not to speak of about 450,000,000,000-1,000,000,000,000 fishes caught for feed annually.
- Feed delivery:
- Feeding frequency and time, feed delivery, self-feeders: in the wild, probably bottom grazer or active fighter [F29]. Some evidence of nocturnal feeding pattern [F11]. If only diurnal feeding times are possible, make sure nocturnal individuals do not starve by closely monitoring individual weights. Alternatively, install a self-feeder and make sure all Whiteleg shrimp adapt to it. No ethology-based recommendation definable so far on feeding frequency as well as speed and pattern of feed delivery. Note decreased feeding in juveniles during days 1.5-3 and 14-21 of the moulting cycle and at temperatures of 20 °C [F17] and reduce the amount of food offered accordingly (if not using a self-feeder).
- Food competition: make sure to provide sufficient feed from ca 38 hours after hatching on [F30]. Large individuals and especially males do feed more often and longer, but females are still heavier [F31], so size-grading might not be beneficial.
- Particle size: for juveniles, provide particle sizes of ca 2.2-2.6 mm; larger particle size results in food competition and probably death of smaller individuals [F26].
- Feed enrichment: to improve metabolic parameters, provide natural food (bacteria, microalgae) in seawater by using 15 μm (instead of smaller) filters [F32]. For lower mortality and better stress resistance, enrich feed with highly unsaturated fatty acids [F32].
- Maturity: in farms, males mature from ca 6.5 months, females from ca 8.5 months on [F4]. Even if manipulating time of maturity were possible, refrain from it, as we have not found studies reporting possible long-term effects on welfare ➝ FishEthoBase's understanding of fish welfare.
- Manipulating sex: even if manipulating sex were possible, refrain from it, as we have not found studies reporting possible long-term effects on welfare ➝ FishEthoBase's understanding of fish welfare.
- Sex ratio: no ethology-based recommendation definable so far. Although females grow bigger and heavier than males [F33], refrain from monosex (female-only) groups, as we have not found studies reporting possible long-term effects on welfare ➝ FishEthoBase's understanding of fish welfare.
- Size-grading: for size-grading and food competition ➝ [R3].
- Other effects on growth:
- Lunar cycle: possibly best growth at full and new moon [F34]. Further research needed.
- Deformities and malformations: no ethology-based recommendation definable so far.
- For growth and...
...substrate ➝ [R4],
...substrate colour ➝ [R4],
...photoperiod ➝ [R5],
...light intensity ➝ [R5],
...water temperature ➝ [R6],
...salinity ➝ [R6],
...particle size ➝ [R3]
...stocking density ➝ [R2].
- Nest building: sea spawner [F35].
- Courtship, mating: respect courtship and mating behaviour in which male chases, turns, and grasps the female [F36]. Allow for touch or mechanical communication respectively [F36] as well as pair bond if individuals display monogamy [F36].
- Spawning conditions: respect natural spawning condition in seawater [F21] and spawning sequence in which male spawns at mating, female 2-5 hours later [F37]. No ethology-based recommendation definable on spawning season, water temperature, salinity, water velocity, and depth. Successful spawning has been achieved in male:female ratios of 1:1 to 6:1 [F38]. Further research needed for wild ratios. Note that wild-caught females mate more frequently than captive ones, but because using wild-caught individuals is not ecologically sustainable, there is no recommendable rearing method at the moment [F39].
- Fecundity: intact/non-ablated females spawn about 30,000-80,000 eggs per mating [F40]. Further research needed for fecundity in the wild. Note the difference in fecundity and consider non- or low-spawning females when estimating productivity of broodstock and refrain from discarding broodstocks altogether. Note that wild-caught females have higher fecundity and more viable spawn than captive ones, but because using wild-caught individuals is not ecologically sustainable, there is no recommendable rearing method at the moment [F41]. Serotonine injection and temperature manipulation for prolonging the spawning period of females to off-season does not yield fecundity, fertilisation, and hatching rates different from – at times even lower than – the control condition [F41]. Further research needed. Although unilateral eyestalk ablation increases fecundity [F40], refrain from it, as it decreases hatching rate [F42], is painful [F43], a profound invasion into the integrity and dignity of the individual, and because we have not found studies reporting possible long-term effects on welfare ➝ FishEthoBase's understanding of fish welfare.
In the wild, males spawn 50,000-29,310,000 sperms per spermatophore [F44]. Note the difference in fecundity and consider non- or low-spawning males when estimating productivity of broodstock and refrain from discarding broodstocks altogether. Although unilateral eyestalk ablation increases fecundity [F44] and spermatophore weight [F41], refrain from it, as it is painful [F43], a profound invasion into the integrity and dignity of the individual, and we have not found studies reporting possible long-term effects on welfare ➝ FishEthoBase's understanding of fish welfare. Refrain from bilateral ablation in males, as it is painful [F43], stressful [F45], a profound invasion into the integrity and dignity of the individual, and increases mortality [F41].
7 Stocking density
- Maximum: the businessplan should be calculated on the basis of a maximum stocking density that will never exceed the tolerable maximum with regard to shrimp welfare.
- Stocking larvae: no ethology-based recommendation definable so far.
- Stocking juveniles and adults: in the wild, densities of 0.001-0.3 individuals/m2, up to 4-5 individuals/m2 in the rainy season [F46]. For better survival and growth, keep at <50 individuals/m2 [F47] [F48]. To determine stocking density in tanks, do not consider bottom plus walls (m3), because Whiteleg shrimp cannot stick to smooth walls. Consider useful surface area (m2) instead – bottom plus substrate [F8].
For artificial substrate to decrease stocking density and stress ➝ [R4].
- Habitat structuring: consider loss of space due to structures inside and outside the system [R4] and calculate density accordingly.
- Environmental conditions: in the wild, displays a large variability in preferences for water temperature [F14] and depth [F25]. Consider increased density at places with preferential conditions [R6] [R7] and calculate density accordingly.
- Aggregation: in farms, individuals build schools [F49]. Consider increased density at places due to formation of schools and calculate density accordingly.
- Aggression: no ethology-based recommendation definable so far.
- Territoriality: no ethology-based recommendation definable so far.
- Interaction: as show the above influence factors, stocking density is only one part of a complex interaction of factors to affect welfare. It should never be considered isolatedly.
- Food search: provide sand and mud and/or artificial substrate (➝ [R4]) so that individuals may search for food [F5] [F29].
- Challenges: if after decreasing stress [R8] and providing everything welfare assuring, you still notice stereotypical behaviour, vacuum activities, sadness, then provide mental challenges, diversion, variety, and check reactions.
9 Handling, slaughter
- Stress coping styles: individuals differ in their ability to cope with stress [F45], so assume the smallest common denominator during stressful situations and handle with care and high efficiency.
- Stress measurement:
- Physiological stress indicators: hemolymph glucose exceeding 5.8-16.7 mg/mL [F50] [F51] [F52] [F45], hemolymph lactate exceeding 3-5.7 mg/dL [F50] [F51], proteins in hemolymph <75.0-90.5 mg/dL [F51], haemocyanin <82.9-96.2 mg/mL [F50] [F52] indicates stress. For acute stress measurement, prefer glucose, for chronic stress measurement, prefer lactate and proteins (among others) in hemolymph [F52].
- Abnormal behaviour: after, e.g., changing parameters, check for behaviour deviating from the norm [F29] [F11] [F53] [F25] [F54] [F33] [F36] [F40] [F44] [F35] [F49] [F55]. Recoiling indicates pain [F43].
- Stress reduction:
- Noise: no ethology-based recommendation definable so far.
- Directing individuals: to direct individuals in the habitat (e.g., for cleaning purposes or to separate moulting from non-moulting individuals), make use of stark light contrasts to reduce stress [F56].
- Cage submergence: does not apply.
- Pain treatment: applying an anaesthetic beforehand and a coagulating agent after a treatment decreases the reactions shown otherwise [F57].
- Handling: handle as carefully as possible and avoid repeated handling (e.g., every day), as it causes stress [F50] [F52]. Especially in newly moulted juveniles, stress will increase mortality [F52]. Avoid bilateral ablation in males, as it causes disorientation and increases mortality [F45].
- Confinement: avoid confinement, as it causes stress [F51]. If unavoidable, after confinement and chasing of one minute, let recuperate for at least two hours [F51].
- Crowding: no ethology-based recommendation definable so far.
- Transport: no ethology-based recommendation definable so far.
- Disturbance: no ethology-based recommendation definable so far.
- For stress reduction and...
...cover ➝ [R4],
...water temperature ➝ [R6],
...salinity ➝ [R6],
...particle size ➝ [R3],
...ablation ➝ [R9],
...stocking density ➝ [R2],
...stunning ➝ [R10].
- Stunning rules: render individuals unconscious as fast as possible and make sure stunning worked and they cannot recover [F58].
- Stunning methods: prefer electrical stunning, because it renders individuals unconscious fast if administered correctly and with appropriate current [F59]. "Crustastun", in particular, effectively stuns and potentially kills decapods like crabs and lobsters with minimal handling and stress involved [F59]. Possibility of epileptic phase, though [F59]. Further research needed to determine whether crustastunning may be applied to Whiteleg shrimp as well and for a specific protocol.
- Slaughter methods: behead individuals immediately after stunning, i.e. while unconscious.
- Certification: fair-fish international association warmly advises to follow one of the established certification schemes in aquaculture in order to improve the sustainability of aquafarming. Adhering to the principles of one of these schemes, however, does not result in animal welfare by itself, because all these schemes do not treat animal welfare as a core issue or as an issue at all. Therefore the FishEthoBase has been designed as a complement to any of the established certification schemes. May it help practitioners to improve the living of the animals they farm based on best scientific evidence at hand.
- To give you a short overview of the most established schemes, we present them below in descending order of their attention for animal welfare (which is not necessarily the order of their sustainability performance):
- The fair-fish farm directives are not present on the market, we cite them here as a benchmark. The directives address fish welfare directly by being committed to FishEthoBase: for each species, specific guidelines are to be developed mirroring the recommendations of FishEthoBase; species not yet described by FishEthoBase cannot be certified. In addition, the directives address a solution path for the problem of species-appropriate feeding without contributing to overfishing.
- The Naturland Standards for Organic Aquaculture (Version 06/2018) generally address animal welfare with words similar to the fair-fish approach: "The husbandry conditions must take the specific needs of each species into account as far as possible (…) and enable the animal to behave in a way natural to the species; this refers, in particular, to behavioural needs regarding movement, resting and feeding as well as social and reproduction habits. The husbandry systems shall be designed in this respect, e.g. with regard to stocking density, soil, shelter, shade and flow conditions".
In the details, however, the standards scarcely indicate tangible directives the only ones for shrimps in general kept in ponds being: provide substrate enlarging the surface and being suitable for growth of benthic algae or diatoms, stocking density limited to 15 post-larvae/m2 max and 1,600 kg/ha in ponds.
- The GAA-BAP Finfish and Crustacean Farms Standard (Issue 2, September 2014) directly addresses animal welfare: "Producers shall demonstrate that all operations on farms are designed and operated with animal welfare in mind." Farms shall "provide well-designed facilities", "minimize stressful situations" and train staff "to provide appropriate levels of husbandry". Yet the standard does not provide tangible and detailed instructions for the practitioner, let alone species-specific directives.
In September 2017, GAA-BAP received a grant from the Open Philanthropy Project to develop best practices and proposed animal welfare standards for salmonids, tilapia, and channel catfish. Thus, fish welfare on GAA-BAP certified farms might become more tangible in the future, eventually also for Pacific whitelg shrimp at a later date.
- The GlobalG.A.P. Aquaculture Standard (Version 4.0, March 2013) "sets criteria for legal compliance, for food safety, worker occupational health and safety, animal welfare, and environmental and ecological care". The inspection form includes criteria like "Is the farm management able to explain how they fulfil their legal obligations with respect to animal welfare?", "If brood fish are stripped, this should be done with the consideration of the animal's welfare." or "Is a risk assessment for animal welfare undertaken?". The scheme claims that 45 out of a total of 249 control points cover animal protection, yet it does not provide any tangible directives, let alone species-specific directives.
- The ASC Aquaculture Stewardship Council. The ASC standards address fish welfare only indirectly, as a function of a “minimum average growth rate" per day, a "maximum fish density at any time", and a "maximum average real percentage mortality". fair-fish sees animal welfare as an intrinsic value, not just as a result of optimising neighbouring values like health care and management procedures.
The ASC standard for Shrimps (version 1.1, March 2019) specifies threshold values for survival rates, but not for stocking density and growth rate.
In November 2017, ASC received a grant from the Open Philanthropy Project to develop an evidence-based fish welfare standard that is applicable to all ASC-certified species. ASC intends to share its approach to fish welfare with all farms engaged with the ASC program and encourage adoption of it, which means that the fish welfare standard will function as a non-mandatory add-on to the ASC certification.
- The Friend of the Sea (FOS) Standards for farmed crustaceans (revised May 2016) do not even address animal health or animal welfare issues.
In May 2017 however, FOS signed a Memory of Understanding with fair-fish international on developing fish welfare criteria for the FOS standard. In November 2017 fair-fish international association received a grant from the Open Philanthropy Project to assess the welfare of fish on FOS certified farms, develop farm-specific recommendations, and to develop animal welfare criteria for the FOS standard. Thus, fish welfare on FOS certified farms might become tangible in the future.