Version: B | 1.0 (2022-09-16)
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)
Ameiurus melas is a nocturnal, bottom-feeder catfish of the Ictaluridae family. It is native from the USA, Canada, and north of Mexico and has been introduced outside of its range in US river basins, many European countries, Puerto Rico, Mexico, and Chile, where it is considered invasive and a nuisance. A. melas is commonly cultured in the USA and Italy, traditionally in ponds. Market size can be achieved in one growing season. Therefore, most cultured A. melas might be JUVENILES. A. melas is a social species, with no migratory behaviour and no aggression reported in captivity nor the wild, which are positive characteristics in cultured FISHES. However, the current farming densities are much higher than what A. melas experiences in the wild, and there are no studies on the effects that these farming conditions might have on the individual well-being. Research showed better growth in ponds than in cages, but new alternatives have been researched in recent years, such as including floating trays in cages to offer cover to the FISHES. There is little information about how A. melas is reproduced in farms, with evidence that FINGERLINGS are obtained from the wild. Therefore, more research needs to be done in this area. A stunning and slaughter protocol needs to be studied and implemented for A. melas as well.
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 farming conditions. It is high for high-standard farming conditions. Our conclusion is based on a medium amount of evidence.
LARVAE and FRY: WILD and FARM: no data found yet.
JUVENILES: WILD: preference for small bodies of water 1 2-3, although also in reservoirs (≥202 ha) 1, lakes (4.5-202 ha 1, 69 ha 4 or ≤200 ha based on a model 5), ponds (≤4 ha) 1 all with unclear home range use. Pool in river tributary: 1,338 m2 (49 x 27 m) 6 with unclear home range use. FARM: FINGERLINGS: ponds: 0.1 ha 7 (26 x 40 m) 8; cages: 1.2 m3 (1 m ∅) in 0.1 ha (26 x 40 m) ponds 8, 4.1 m2 (2.4 x 1.7 m) or 2.9 m2 (1.7 x 1.7 m ) in 0.7 ha pond 9; fibreglass tanks in RAS: 2 m3 7 10; concrete tanks: 240 m3 11.
ADULTS: WILD: preference for small bodies of water 1 2-3, although also in reservoirs (≥202 ha) 1, lakes (4.5-202 ha 1, 69 ha 4 or ≤200 ha based on a model 5), ponds (≤4 ha) 1, bay (320 ha) 12 all with unclear home rang euse. Pool in river tributary: 1,338 m2 (49x27 m) 6 with unclear home range use. FARM: ponds: 0.1 ha 7; cages: 4.1 m2 (2.4 x 1.7 m) or 2.9 m2 (1.7 x 1.7 m ) in 0.7 ha pond 9; fibreglass tanks in RAS: 2 m3 7.
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 medium amount of evidence.
LARVAE and FRY: WILD and FARM: no data found yet.
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 high for high-standard farming conditions. Our conclusion is based on a medium amount of evidence.
JUVENILES: WILD: diurnal: active during the day with feeding behaviour at dawn (peak at 05:00 h) and dusk (20:00-22:00 h) 6 15, inactive at night (22:00-04:00 h) 6. Feeding associated to dim lights, swimming/social activity to bright light 6. Optimal temperature for growth 18-29 °C 5. Salinity tolerance based on other catfish information ≤2 ppt, lethal at 14 ppt 5. FARM: PHOTOPERIOD not manipulated 7.
ADULTS: WILD: nocturnal: inactive during the day with foraging behaviour starting at dusk and returning to pool shortly before dawn 6 15. Tolerate high temperatures (≤35 °C) 20-3, but optimal for growth 18-29 °C 5. Salinity tolerance based on other catfish information ≤2 ppt, lethal at 14 ppt 5. FARM: ➝ 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?It is low for minimal and high-standard farming conditions. Our conclusion is based on a medium amount of evidence.
WILD: spawn in May or June 15, April-June 17 21 or May-July 22-5 at 20-21 °C 17 22-5 or 21-24 °C 4 when they are 3 years old 21 or 13.3 cm (2 years old) 4. Mating ritual 17. Mating lasts >1 h over several days 17. Sex ratio during mating: 1:1 5, in the population: 0.9-1.0 male:female 4. Parental care (male and female) of the nest after spawning 23-24 13-5 15 16 17 and of LARVAE and FRY after hatching 15 16 17. Parental care after hatching only by male 17, only by female 21 or by both 23-24. For nest building ➝ crit. 7. FARM: FINGERLINGS probably obtained from the wild 25 7. LAB: successful out-of-season reproduction after hormonal injection to females 14. Mating ritual 14. Parental care of the eggs by female on the 1st day and by male on 2nd and 3rd days 14.
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: social, in high densities 24 15, although frequently isolated during winter when inactive and grouping again when active 24. Schooling behaviour 24 6 15 associated to bright light, in loose schools when swimming upstream and tight schools when swimming downstream with little lateral movements 6. Group foraging 15. Tendency to overcrowding and subsequent slow growth 26. Pond: average 184 kg/ha 26, maximum 942 kg/ha 26; lake: 355 IND/ha (mixed with ADULTS) 4; small lakes: average 21 kg/ha 1; large lakes: 50 kg/ha 1; reservoirs: insignificant population 1. FARM: FINGERLINGS: cages: 141-424 IND/m3 25, 17.5 kg/m3 9; cages in ponds: 125 IND/m3 8; fibreglass tanks in RAS: 1,570 IND/m3 (8 kg/m3) 7, 1,000 IND/m3 10; ponds: 4,500 IND/ha 8, 15 IND/m3 (0.07 kg/m3) 7; concrete tanks: 4.2 kg/m3 11.
ADULTS: WILD: social 6, occasionally in high densities 15. Tendency to overcrowding and subsequent slow growth 26. Lake: 355 IND/ha (mixed with JUVENILES, only 1% of desirable fishing size) 4; pond: average 184 kg/ha 26, maximum 942 kg/ha 26; small lakes: average 21 kg/ha 1; large lakes: 50 kg/ha 1; reservoirs: insignificant population 1. FARM: pond: 1.9 kg/m3 7; fibreglass tanks in RAS: 235.5 kg/m3 7. LAB: resting in social contact during daytime 24.
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 high for minimal and high-standard farming conditions. Our conclusion is based on a medium amount of evidence.
LARVAE and FRY: WILD and FARM: no data found yet. LAB: no aggression reported 24.
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 medium for high-standard farming conditions. Our conclusion is based on a medium amount of evidence.
LARVAE and FRY: WILD: soft bottoms made of mud, silt, and sand, sometimes mixed with gravel 17 20-3. Preference a) for turbid, silty water with little or no current and b) for silty substrate 15 17. FARM: no data found yet.
JUVENILES: WILD: soft bottoms made of mud, silt, and sand, sometimes mixed with gravel and rocks 6 17 20-3, covered with dense vegetation beds absent in some areas 6. Preference a) for turbid, silty water with little or no current and b) for silty substrate 15 17. Preference for vegetative areas vs bottom of pool for foraging purposes 6. Rest in vegetation bed overnight 6. Pools/lakes with ≥20% cover (vegetation, brush or debris) 5 27-5. FARM: fibreglass tanks in RAS: 0.5 m2 floating tray to offer cover and make use of water column by IND 7. For details of holding systems ➝ crit. 1 and 2. LAB: extensive use of brick cover, some use of plant cover 28.
ADULTS: WILD: soft bottoms made of mud, silt, and sand, sometimes mixed with gravel and rocks 6 17 20-3 covered with dense vegetation beds absent in some areas 6. Preference a) for turbid, silty water with little or no current and b) for silty substrate 15 17. Preference for vegetative cover except during feeding time 6. Rest in vegetation bed during daytime 6. Thigmotaxis: preference for contact with solid objects or resting on depressions in the ground 24. Pools/lakes with ≥20% cover (vegetation, brush or debris) 5 27-5. Good population densities at 100-350 ppm Total Dissolved Solids 29-5, but also tolerate ≤4430 ppm 30-5. FARM: fibreglass tanks in RAS: 0.5 m2 floating tray to offer cover and make use of water column by IND 7. For details of holding systems ➝ crit. 1 and 2.
SPAWNERS: WILD: females build nests in muddy substrate of >50% of fines 31-5 beneath logs or other objects 31-5 15 16 17 or in areas with matted vegetation 17 18-5 ≥20% 5. FARM: no data found yet. LAB: females built nests 14.
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?There are unclear findings for minimal and high-standard farming conditions. Our conclusion is based on a low amount of evidence.
LARVAE and FRY: no data found yet.
JUVENILES: mortality, probably caused by injuries during handling and transportation 9.
ADULTS: ➝ JUVENILES.
SPAWNERS: no data found yet.
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 unclear findings for minimal and high-standard farming conditions. Our conclusion is based on a low amount of evidence.
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 medium for high-standard farming conditions. Our conclusion is based on a low 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 3 35, 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)?
WILD: FRY and JUVENILES: omnivorous 15, mostly crustaceans 16 6 . ADULTS: omnivorous 16, insectivorous 15, mostly aquatic insects and crustaceans 16, but also other FISHES, aquatic vegetation, and detritus 4. FARM: fish meal may be partly* replaced by sustainable sources 36, but no data found yet for ADULTS and SPAWNERS.
*partly = <51% – mostly = 51-99% – completely = 100%
DOMESTICATION LEVEL 3 = entire life cycle closed in captivity with wild inputs 35
FARM = setting in farming environment or under conditions simulating farming environment in terms of size of facility or number of individuals
FINGERLINGS = early juveniles with fully developed scales and working fins, the size of a human finger; for details ➝ Findings 10.1 Ontogentic development
FISHES = Using "fishes" instead of "fish" for more than one individual - whether of the same species or not - is inspired by Jonathan Balcombe who proposed this usage in his book "What a fish knows". By referring to a group as "fishes", we acknowledge the individuals with their personalities and needs instead of an anonymous mass of "fish".
FRY = larvae from external feeding on, for details ➝ Findings 10.1 Ontogenetic development
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
PHOTOPERIOD = duration of daylight
SPAWNERS = adults during the spawning season; in farms: adults that are kept as broodstock
WILD = setting in the wild
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