Version: B | 1.1 (2022-06-23)
Please note: This part of the profile is currently being revised.
Condensed assessment of the species' likelihood and potential for good fish welfare in aquaculture, based on ethological findings for 10 crucial criteria.
Li = Likelihood that the individuals of the species experience good welfare under minimal farming conditions
Po = Potential of the individuals of the species to experience good welfare under high-standard farming conditions
Ce = Certainty of our findings in Likelihood and Potential
FishEthoScore = Sum of criteria scoring "High" (max. 10)
Oreochromis niloticus is a very resilient and well-known species to the aquaculture industry. However, it requires a series of features to ensure its welfare in farming conditions. Intensive farming may disrupt natural reproductive cycles and fails to ensure that proper substrate and shelter are provided. Semi-intensive culture respect some spatial and habitat needs, but most industrial farming, especially in floating cages, does not. Although a remarkable amount of research has been conducted, another issue that needs to be tackled is wild-caught fish for feed. This should be replaced by fish slaughterhouse waste and other sources or avoided by extensive farming fully based on sustainable sources.
1 Home range
Many species traverse in a limited horizontal space (even if just for a certain period of time per year); the home range may be described as a species' understanding of its environment (i.e., its cognitive map) for the most important resources it needs access to. What is the probability of providing the species' whole home range in captivity?There are unclear findings for minimal farming conditions. It is high for high-standard farming conditions. Our conclusion is based on a medium amount of evidence.
LARVAE: WILD: maternally mouthbred 1 2 3 4 5, young remain close to the mother 6. FARM: <4 m3 7.
JUVENILES: WILD: move considerably between feeding and breeding grounds 6. FARM: grow-out ponds: 690 8, 2000 m2 7; hapas: 120 m2 7; cages 6-600 m3 8.
ADULTS: ➝ JUVENILES:
SPAWNERS: WILD: males: 2-10 m 9; mouthbreeding females move away from spawning grounds, unknown distance 6. FARM: spawning ponds: < 2000 m2 7; hapas: 120 m2 7; raceways: 12 m2 8.
2 Depth range
Given the availability of resources (food, shelter) or the need to avoid predators, species spend their time within a certain depth range. What is the probability of providing the species' whole depth range in captivity?It is low for minimal farming conditions. It is high for high-standard farming conditions. Our conclusion is based on a high amount of evidence.
Eggs: WILD: maternally mouthbred 1 2 3 4 5. FARM: incubation jars 7.
LARVAE: WILD: maternally mouthbred 1 2 3 4 5, usually in shallow habitats 10 6. FARM: nursery concrete tanks: 0.5-2 m 8; earthen ponds: ca 1 m 8; intensive artificial larval rearing systems: ca 20 cm 8.
JUVENILES: WILD: usually 0-6.7 m 11 3, occasionally below 30 m 12. Move deeper with decreasing water temperatures and shallower with increasing water temperatures 13. FARM: grow-out concrete tanks: 1-2 m 13 8; ponds: 0.5-3 m 13 8; cages: 2-4 m 8.
ADULTS: ➝ JUVENILES
SPAWNERS: WILD: build nests in shallow waters 12, usually at 0.6-2 m 14. FARM: spawning concrete tanks: 0.5-2 m; earthen ponds: ca 1 m 8.
Some species undergo seasonal changes of environments for different purposes (feeding, spawning, etc.) and with them, environmental parameters (photoperiod, temperature, salinity) may change, too. What is the probability of providing farming conditions that are compatible with the migrating or habitat-changing behaviour of the species?It is high for minimal and high-standard farming conditions. Our conclusion is based on a high amount of evidence.
Typically resident in fresh water 15 6. Able to adapt to brackish water 2.
LARVAE: WILD: maternally mouthbred in fresh or brackish water 1 2 3 4 5. FARM: nursery freshwater ponds 7. For details of holding systems ➝ crit 1 and 2.
JUVENILES: WILD: fresh water, perform temperature-related depth displacements 13. FARM: reared in fresh water 8 7. White light increased ventilatory frequency after confinement 16. For details of holding systems ➝ crit 1 and 2.
ADULTS: ➝ JUVENILES.
A species reproduces at a certain age, season, and sex ratio and possibly involving courtship rituals. What is the probability of the species reproducing naturally in captivity without manipulation of theses circumstances?It is high for minimal and high-standard farming conditions. Our conclusion is based on a high amount of evidence.
WILD: breed in a lek system: many males gather in an arena to display to females around it. Each male digs and defends a pit in sandy substrate where he performs elaborate behaviours, changes colour and sometimes chases females into the pit. One female then lays the eggs in the pit, the male fertilizes the clutch and the female grabs the fertilized eggs with her mouth, swimming away 6 17 18 19. FARM: spawns easily and spontaneously in hapas, earthen ponds and concrete tanks 8 (although these lack substrate) but not in floating cages - which therefore are not used for spawning 7.
Species differ in the way they co-exist with conspecifics or other species from being solitary to aggregating unstructured, casually roaming in shoals or closely coordinating in schools of varying densities. What is the probability of providing farming conditions that are compatible with the aggregation behaviour of the species?There are unclear findings for minimal farming conditions. It is high for high-standard farming conditions. Our conclusion is based on a medium amount of evidence.
LARVAE: WILD: maternally mouthbred 1 2 3 4 5, spend early life stages in same-age group of siblings 5. Fry form large schools 20. FARM: extensive and semi-intensive systems: eggs hatch and larvae develop with mothers in spawning tanks or ponds 8; artificial hatching systems in intensive rearing: 2-10 fry/L 21.
JUVENILES: WILD: live in groups of unknown, variable sizes in the wild 6 10 5. FARM: form groups in captivity 22 23. Semi-intensive ponds: 1-3 juveniles/m2; raceways and floating cages: 200-300 juveniles/m3 7. LAB: increased stress in groups of 10 IND than in singly-held IND or pairs, lower growth in groups of 5 or 10 IND, probably indicating crowding stress 24.
ADULTS: ➝ JUVENILES.
SPAWNERS: WILD: gather in leks (i.e. spawning arenas) 6 8. FARM: 2-28 adults/m2 in 1 male : 3 females sex ratio 8.
There is a range of adverse reactions in species, spanning from being relatively indifferent towards others to defending valuable resources (e.g., food, territory, mates) to actively attacking opponents. What is the probability of the species being non-aggressive and non-territorial in captivity?It is low for minimal farming conditions. It is medium for high-standard farming conditions. Our conclusion is based on a medium amount of evidence.
LARVAE: WILD: maternally mouthbred 1 2 3 4 5, spend early life stages in same-age group of siblings 5. FARM: fry form large schools 20. No reports of aggression.
JUVENILES: WILD: territorial, aggressive in the wild 15 25 26 27 28 29. FARM: aggression decreases severely when density increases 30 31.
ADULTS: ➝ JUVENILES.
SPAWNERS: WILD and FARM: territorial, aggressive within the spawning season 15 25 26 27 29.
Depending on where in the water column the species lives, it differs in interacting with or relying on various substrates for feeding or covering purposes (e.g., plants, rocks and stones, sand and mud). What is the probability of providing the species' substrate and shelter needs in captivity?It is low for minimal farming conditions. It is high for high-standard farming conditions. Our conclusion is based on a high amount of evidence.
Eggs and LARVAE: WILD: maternally mouthbred 1 2 3 4 5, usually in shallow sandy vegetated habitats 10. FARM: substrate present in earthen ponds 8 32.
JUVENILES: WILD: BENTHIC, use substrate for feeding 33 11 34 35. FARM: grow better with substrate 32, which is present in earthen ponds 8 32.
ADULTS: ➝ JUVENILES.
SPAWNERS: WILD: BENTHIC, use substrate for feeding 33 11 34 35 and spawning 18 19 6 21 10 5 36. FARM: substrate present in earthen ponds 8 32, but are able to spawn without substrate 8.
Farming involves subjecting the species to diverse procedures (e.g., handling, air exposure, short-term confinement, short-term crowding, transport), sudden parameter changes or repeated disturbances (e.g., husbandry, size-grading). What is the probability of the species not being stressed?It is low for minimal farming conditions. It is medium for high-standard farming conditions. Our conclusion is based on a medium amount of evidence.
Deformities that – in contrast to diseases – are commonly irreversible may indicate sub-optimal rearing conditions (e.g., mechanical stress during hatching and rearing, environmental factors unless mentioned in crit. 3, aquatic pollutants, nutritional deficiencies) or a general incompatibility of the species with being farmed. What is the probability of the species being malformed rarely?It is high for minimal and high-standard farming conditions. Our conclusion is based on a high amount of evidence.
LARVAE: no influence of intense inbreeding on fry malformation rates: 3-8% 40.
JUVENILES: low rate (1.5-2.7%) of skeletal deformities (lateral projections of the mandible, 'parrot-like head', scoliosis, kyphosis, lordosis, fusion of dorsal and anal fins) 41 when compared to other farmed species such as sea bass (30%) 42, sea bream (>10%) 43 or catfish (5%) 41.
ADULTS: ➝ JUVENILES.
The cornerstone for a humane treatment is that slaughter a) immediately follows stunning (i.e., while the individual is unconscious), b) happens according to a clear and reproducible set of instructions verified under farming conditions, and c) avoids pain, suffering, and distress. What is the probability of the species being slaughtered according to a humane slaughter protocol?It is low for minimal farming conditions. It is high for high-standard farming conditions. Our conclusion is based on a high amount of evidence.
Side note: Domestication
Teletchea and Fontaine introduced 5 domestication levels illustrating how far species are from having their life cycle closed in captivity without wild input, how long they have been reared in captivity, and whether breeding programmes are in place. What is the species’ domestication level?
DOMESTICATION LEVEL 5 49, fully domesticated.
Side note: Forage fish in the feed
450-1,000 milliard wild-caught fishes end up being processed into fish meal and fish oil each year which contributes to overfishing and represents enormous suffering. There is a broad range of feeding types within species reared in captivity. To what degree may fish meal and fish oil based on forage fish be replaced by non-forage fishery components (e.g., poultry blood meal) or sustainable sources (e.g., soybean cake)?
WILD: Omnivorous 11 12 33 50. FARM: fish feed and fish oil may be mostly* 51 or completely* replaced by non-forage fishery products 52 53 54 , especially in integrated farming 8 or non-industrial practices (urban aquaponic) 55.
*partly = <51% – mostly = 51-99% – completely = 100%
BENTHIC = living at the bottom of a body of water, able to rest on the floor
DOMESTICATION LEVEL 5 = selective breeding programmes are used focusing on specific goals 49
FARM = setting in farming environment or under conditions simulating farming environment in terms of size of facility or number of individuals
IND = individuals
JUVENILES = fully developed but immature individuals, for details ➝ Findings 10.1 Ontogenetic development
LAB = setting in laboratory environment
LARVAE = hatching to mouth opening, for details ➝ Findings 10.1 Ontogenetic development
SPAWNERS = adults during the spawning season; in farms: adults that are kept as broodstock
WILD = setting in the wild
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