Short profile


FishEthoScore of the species

Abbreviated assessment of the species' likelihood and potential for fish welfare in aquaculture, based on ethological findings for 10 crucial criteria.

Criteria Li Po Ce
1 Home range
2 Depth range
3 Migration
4 Reproduction
5 Aggregation
6 Aggression
7 Substrate
8 Stress
9 Malformation / / /
10 Slaughter ?
FishEthoScore 0 1 3
Li = Likelihood that the individuals of the species experience welfare under minimal farming conditions
Po = Potential overall potential of the individuals of the species to experience welfare under improved farming conditions
Ce = Certainty of our findings in Likelihood and Potential
 
                    ?     /  
  High    Medium     Low     Unclear  No findings
 
FishEthoScore = Sum of criteria scoring "High" (max. 10)



General remarks

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 conversion 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. Are minimal farming conditions likely to provide the home range of the species? Is there potential for improvement? How certain are these findings?

L
Likelihood
L
Potential
H
Certainty

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: ➝ JUVENILESFARM: no data found yet.


2. Are minimal farming conditions likely to provide the depth range of the species? Is there potential for improvement? How certain are these findings?

L
Likelihood
M
Potential
H
Certainty

LARVAE: WILD: near the sea bottom during the day and near the surface during the night (nictemeral feeding migrations) [5] [6]. FARM: 500-1,000 L cylindro-conical tanks: ~0.5-1 m [1].

JUVENILES: WILD: 0-200 m, mostly <50 m [7] [8] [9] [10]. FARM/LAB: inland tanks: ~0.5-1 m, floating cages in the sea: 0.5-2 m depth, submerged sea-bottom cages: ~0.5-2 m high, at a maximum of 25 m depth [1].

ADULTS: ➝ JUVENILES.

SPAWNERS:➝ JUVENILES.


3. Are minimal farming conditions compatible with the migrating or habitat-changing behaviour of the species? Is there potential for improvement? How certain are these findings?

L
Likelihood
M
Potential
M
Certainty

LARVAE: WILD: PELAGIC paralarvae inhabiting water column with nictemeral migrations, photoperiod 9-15 h, temperature 11-28 °C, saltwater [5] [6]. FARM/LAB: photoperiod 12 h, temperature 21 °C, salinity 36.8±0.1 ups [11]. For details of holding systems ➝ crit. 1 and 2. 

JUVENILES: sedentary, limited seasonal migrations [5] [9]. Maximum distance recorded: <5 km [12]. Plausibly, if the habitat offers food, shelter, and mating opportunities, octopuses are not forced to undertake long-distance movements [2]. FARM/LAB: optimum water temperature for growth: 16-19 ºC [13] [14] [15]. For details of holding systems ➝ crit. 1 and 2. 

ADULTS: ➝ JUVENILES.

SPAWNERS: ➝ JUVENILES.


4. Is the species likely to reproduce in captivity without manipulation? Is there potential to allow for it under farming conditions? How certain are these findings?

L
Likelihood
M
Potential
M
Certainty

WILD: maturation at about 300-350 g in males and about 400-500 g in females [5] [16]. Strong spawning peaks in spring and a second lower spawning peak in autumn is plausible [17] [5]. Incubation period (embryonic development): 20 days-4 months, depending on water temperature [18] [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 [19]. Extremely high mortality rates of paralarvae on rearing conditions [1].


5. Is the aggregation imposed by minimal farming conditions likely to be compatible with the natural behaviour of the species? Is there potential to allow for it under farming conditions? How certain are these findings?

L
Likelihood
L
Potential
H
Certainty

LARVAE: WILD: PLANKTONIC, natural aggregations due to coastal water currents or upwellings [5]. FARM: 3-48 ind/L [1].

JUVENILESWILD: usually solitary, asocial [7] [20]. FARM/LAB: 8-24.5 kg/m3 [21] [22]. Higher survival rates with lower densities [22]. Optimal density range: 5-15 kg/m3 [1]. It is highly recommended to separate individuals by sex [14].

ADULTS: ➝ JUVENILES.

SPAWNERS: WILD: spawning aggregations [7] [20]. FARM: density should not exceed 5 kg/m3 [11].


6. Is the species likely to be non-aggressive and non-territorial? Is there potential for improvement? How certain are these findings?

L
Likelihood
L
Potential
M
Certainty

LARVAE: WILD: no data found yet. FARM/LAB: aggression and cannibalism [23].

JUVENILES: WILD: despite their solitary habit, no signs of territoriality or dominance relationships [24] [25] [26]. 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 [14]. Cannibalism and autophagy reported with hierarchical size classes [1].

ADULTS: WILD: cannibalism on large individuals [27]. FARM: ➝ JUVENILES.

SPAWNERS: WILD: potential cannibalism during mating: aggressive female against male [27]. FARM: ➝ JUVENILES.


7. Are minimal farming conditions likely to match the natural substrate and shelter needs of the species? Is there potential for improvement? How certain are these findings?

L
Likelihood
H
Potential
M
Certainty

LARVAE: WILD: PELAGIC. FARM: black tanks recommended [11] [28]. For details of holding systems crit. 1 and 2.

JUVENILES: WILD: prefer soft-bottom substrates [8] [17] [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] [17] [10] [29]. FARM/LAB: during settlement, benefit from shelters and pebbles on the bottom [30] [21]. Individual shelters can reduce mortality and aggression [14] [21] [15] [31] [32] [1] [33].

ADULTS: WILD: prefer hard-bottom substrates [34]. 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] [17] [10] [29]. FARM/LAB: ➝ JUVENILES.

SPAWNERS: WILD: prefer hard-bottom substrates [34]. 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] [17] [10] [29]. FARM: individual shelters facilitate egg laying [1].


8. Are minimal farming conditions (handling, confinement etc.) likely not to stress the individuals of the species? Is there potential for improvement? How certain are these findings?

L
Likelihood
M
Potential
M
Certainty

LARVAE: stressed by unsuitable water conditions (temperature and salinity levels, etc.), confinement characteristics, and high rearing densities [1].

JUVENILES: stressed by food deprivation, hierarchy (different sizes), high densities, unsuitable artificial light and water conditions (temperature and salinity levels, etc.), confinement characteristics, and by handling and transportation [1] [35]. Smaller individuals are more sensitive to water temperature [36] and increases in water temperature [37]. High mortalities (47-88%) when water temperature was >28 °C or <10 °C [38]. Skin damaged by handling and confinement makes the animal susceptible to secondary infections (bacterial, parasites) which can be fatal if untreated [39]. Stressed by the use of analgesics and anaesthetics [35].

ADULTS: ➝ JUVENILES.

SPAWNERS: ➝ JUVENILES.


9. Are malformations of this species likely to be rare under farming conditions? Is there potential for improvement? How certain are these findings?

/
Likelihood
/
Potential
/
Certainty

No data found yet.


10. Is a humane slaughter protocol likely to be applied under minimal farming conditions? Is there potential for improvement? How certain are these findings?

?
Likelihood
L
Potential
M
Certainty

Common slaughter method: no data found yet. Indications that stunning by immersion in MgCl2, followed by spiking of the brain is most effective [40]. Further research needed to confirm for farming conditions.


Side note: Domestication

Domestication level 3 [41], level 5 being fully domesticated.


Side note: Feeding without components of forage fishery

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%


Glossary

ADULTS = mature individuals, for details Findings 10.1 Ontogenetic development
FARM = setting in farm environment
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
PLANKTONIC = horizontal movement limited to hydrodynamic displacement
SPAWNERS = adults that are kept as broodstock
WILD = setting in the wild


Bibliography

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