Version: B | 1.1 (2022-03-25)
WelfareScore | farm
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
WelfareScore = Sum of criteria scoring "High" (max. 10)
Octopus vulgaris has recently aroused much interest in aquaculture, considered suitable for large-scale production given its commercial value, its fecundity, rapid growth, high protein content, and high feed efficiency rate. The main problem, however, is the high mortality rate observed during paralarval rearing, making successful juvenile settlement still very difficult to achieve. Unfortunately, despite the high knowledge on the biology and ethology of this species, there are many other aspects to be solved from a welfare perspective. For instance, the current farming systems result in high stress in O. vulgaris due to spatial constraint, high densities, and sociability, which consequently increase aggression (cannibalism and autophagy) at different life stages. In addition, octopus skin is particularly sensitive and can be easily damaged during handling, transportation or stressful confinement conditions. A humane slaughtering protocol is not yet established, since the nature and degree of any suffering during current practices are unknown. O. vulgaris appears capable of experiencing pain and suffering, exhibits cognitive complexity and sophisticated behavioural patterns which can be interpreted and serve as indicator of the welfare status.
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?It is low for minimal and high-standard farming conditions. Our conclusion is based on a high amount of evidence.
LARVAE: WILD: no data found yet. FARM/LAB: 500-1,000 L cylindro-conical tanks: ~0.5-1.5 m Ø 1.
JUVENILES: WILD: 2.8-7.3 ha, median home range radius: 121.8 m 2. High site fidelity (<1 km distance); movement depends on food and shelter availability 3 4. FARM/LAB: inland tanks: ~1-2 m Ø, floating cages in the sea: ~2-4 m3, submerged sea-bottom cages: ~2-4 m3 1.
ADULTS: ➝ JUVENILES.
SPAWNERS: WILD: mature females are immovable; move inside dens to spawn and care for the eggs until hatching without feeding 5. Males: ➝ JUVENILES. FARM: no data found yet.
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 medium for high-standard farming conditions. Our conclusion is based on a high amount of evidence.
ADULTS: ➝ JUVENILES.
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 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: PELAGIC paralarvae inhabiting water column with nictemeral migrations, 9-15 h PHOTOPERIOD, saltwater 5 6. FARM/LAB: 12 h PHOTOPERIOD, 16-26 °C temperature, 32-36 psu salinity 11 12. Stressed by unsuitable water conditions (temperature and salinity levels, etc.) 1. For details of holding systems ➝ crit. 1 and 2.
JUVENILES: WILD: sedentary, limited seasonal migrations 5 9. Maximum distance recorded: <5 km 13. Plausibly, if the habitat offers food, shelter, and mating opportunities, octopuses are not forced to undertake long-distance movements 2. FARM/LAB: stressed by unsuitable water conditions (temperature and salinity levels, etc.) 1. Smaller individuals are more sensitive to water temperature 14 and increases in water temperature 15. High mortalities (47-88%) when water temperature was >28 °C or <10 °C 16. For details of holding systems ➝ crit. 1 and 2.
ADULTS: ➝ JUVENILES.
SPAWNERS: ➝ 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 low for minimal farming conditions. It is medium for high-standard farming conditions. Our conclusion is based on a medium amount of evidence.
WILD: maturation at about 300-350 g in males and about 400-500 g in females 5 17. Strong spawning peaks in spring and a second lower spawning peak in autumn is plausible 18 5. Incubation period (embryonic development): 20 days-4 months, depending on water temperature 19 5. During spawning, mature females remain inside dens to care for the eggs until hatching without feeding, usually dying after hatch 5. High natural mortality rates on paralarvae life stage 5. FARM: when keeping wild adult males and females together under suitable environmental conditions (filtered seawater, minimal renewal rate: 400-800%/d, dissolved oxygen levels around 100%, water salinity and temperature mimicking natural conditions, not <14 °C nor >25 °C) and providing them with shelters, nearly 100% of females can mature and lay fertile egg strings 11. Semi-dark conditions are commonly used, but natural PHOTOPERIOD with shaded natural light is also utilised 20. Extremely high mortality rates of paralarvae 1.
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?It is low for minimal and high-standard farming conditions. Our conclusion is based on a high amount of evidence.
JUVENILES: WILD: usually solitary, asocial 7 21. FARM/LAB: 8-24.5 kg/m3 22 23. Higher survival rates with lower densities 23. Optimal density range: 5-15 kg/m3 1. It is highly recommended to separate individuals by sex 24.
ADULTS: ➝ JUVENILES.
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 and high-standard farming conditions. Our conclusion is based on a medium amount of evidence.
LARVAE: WILD: no data found yet. FARM/LAB: aggression and cannibalism 25.
JUVENILES: WILD: despite their solitary habit, no signs of territoriality or dominance relationships 26 27 28. FARM: little but evidenced cannibalism of large individuals towards smaller newly introduced specimens in suspended cages with segregation of sexes, high number of dens, and sufficient food supply 24. Cannibalism and autophagy reported with hierarchical size classes 1.
ADULTS: WILD: cannibalism on large individuals 29. FARM: ➝ JUVENILES.
SPAWNERS: WILD: potential cannibalism during mating: aggressive female against male 29. FARM: ➝ JUVENILES.
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 medium amount of evidence.
LARVAE: WILD: PELAGIC. FARM/LAB: black 11 or opaque grey tanks without mirrored surfaces 12 30, layer of sand 12, and den for each individual recommended 12. For details of holding systems ➝ crit. 1 and 2.
JUVENILES: WILD: prefer soft-bottom substrates 8 18 10. Overall, occur mostly on rocky, sandy, and muddy bottom or in seagrass, but also utilise solid material available (rocks, stones, shells, anthropogenic litter, etc.) for den construction 8 18 10 31. FARM/LAB: opaque grey tanks without mirrored surfaces 12 30, layer of sand 12, and den for each individual recommended 12. During settlement, benefit from shelters and pebbles on the bottom 32 22. Individual shelters can reduce mortality and aggression 24 22 33 34 35 1 36.
ADULTS: WILD: prefer hard-bottom substrates 37. Overall, occur mostly on rocky, sandy, and muddy bottom or in seagrass, but also utilise solid material available (rocks, stones, shells, anthropogenic litter, etc.) for den construction 8 18 10 31. FARM/LAB: ➝ JUVENILES.
SPAWNERS: WILD: ➝ ADULTS. FARM: individual shelters facilitate egg laying 1.
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.
LARVAE: for stress and a) unsuitable water conditions ➝ crit. 3, b) stocking density ➝ crit. 5.
JUVENILES: stressed by handling and transportation 12. Skin damaged by handling and confinement makes the animal susceptible to secondary infections (bacterial, parasites) which can be fatal if untreated 38. Stressed by the use of analgesics and anaesthetics 12. For stress and a) unsuitable water conditions ➝ crit. 3, b) stocking density ➝ crit. 5.
ADULTS: ➝ JUVENILES.
SPAWNERS: ➝ JUVENILES.
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?There are no findings for minimal and high-standard farming conditions.
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?There are unclear findings for minimal farming conditions. It is low for high-standard farming conditions. Our conclusion is based on a medium amount of evidence.
Common slaughter method: no data found yet. High-standard slaughter method: indications that stunning by immersion in MgCl2, followed by spiking of the brain is most effective 39. Further research needed to confirm for farming conditions.
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 3 40, level 5 being 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)?
All age classes: WILD: carnivorous 42 43 44 45 6 46. FARM: fish oil may be completely* omitted 47. Fish meal may be mostly* replaced by non-forage fishery components 48. In Octopus maya, fish meal may be completely* replaced by non-forage fishery components 49. Further research to determine whether this applies to O. vulgaris as well.
*partly = <51% – mostly = 51-99% – completely = 100%
DOMESTICATION LEVEL 3 = entire life cycle closed in captivity with wild inputs 41
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
PELAGIC = living independent of bottom and shore of a body of water
PHOTOPERIOD = duration of daylight
PLANKTONIC = horizontal movement limited to hydrodynamic displacement
SPAWNERS = adults during the spawning season; in farms: adults that are kept as broodstock
WILD = setting in the wild
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