“ablated shrimps were more likely to flick their tails and rub the area of the wound (Diarte-Plata et al., 2012)”
“when the wound was covered or anaesthetic administered, the shrimps reduced these responses”
eyestalk ablation also negatively impacts mortality, biomarkers of stress, and weight loss
Combat disease with protocols regarding disinfection, biosecurity, hygiene, and pond preparation
Slaughter via electrical stunning
“Shrimps are typically slaughtered by either asphyxiation (suffocation) or immersion in ice slurry (chilling) (Weis 2022, at 2min,15sec)”
Electric stunning seems like a more reliable way to quickly render shrimps unconscious.
Only keep 6-15 shrimps per m2
(Note that this number is tentative)
Shrimps tend to distance themselves at high density (Da Costa et al. 2016)
High stocking density is associated with:
Difficulty accessing feed
Reduced water quality (dissolved oxygen, un-ionised ammonia, water hardness)
Increased disease
Increased mortality
Physical injury
Cannibalism
Increased serotonin (stress biomarker)
More frequent movement (stress related?)
At densities below 6 shrimps/m2, “dominance hierarchies become more prominent, and feed consumption diminishes due to the absence of social cues (Bardera et al., 2020)”
Fish studies have also shown negative effects of very low density
Enrich environments
Including “feeding methods that mimic natural behaviours, hiding sites, different tank shapes and colours, plants, substrates, and sediments.”
“In the wild, decapods spend much of their time sheltering in the dark, and should therefore be given access to dark environments (Birch et al., 2021, p.70).”
For fish environmental enrichment has led to “increased social interaction, less abnormal behaviour, and reduced captivity-related stress (Arechavala-Lopez et al., 2022)”
“For L. vannamei maturation tanks, tanks with dark backgrounds and rounded shape are recommended (FAO, 2003, p.22). ”
Improve handling practices
Reduce injury from trawling (fishing by pulling net behind a boat)
Imposing maximum packing weight to prevent shrimps from being crushed and not suffocating (hypoxia)
Improve nutrition
Inadequete nutrition leads to soft shell syndrome, aggression, cannibalism
“Overfeeding, on the other hand, may lead to the build-up of toxic ammonia (Alune, 2020) and increased turbidity”
Improve water quality
Dissolved oxygen between 5 and 8 mg/L.
Un-ionised ammonia <0.05 mg/L
pH of 7.8 to 8.2
temperatures of 28-30°C
salinities between 0.5‰ and 45‰
The report focused on whiteleg shrimp “due to the scale and intensity of farming (~171-405 billion globally per annum) (Mood and Brooke, 2019)”
I tried to extract out the key data because I was wondering how anyone can know what shrimp like. They’re simple alien creatures.
It seems like the presence of these factors are used to indicate “this is bad for shrimps”:
Mortality
Disease
Stress biomarkers (eg serotonin)
Recoil reflex (ie, eyestalk ablation)
An injury-rubbing behaviour that diminishes with covering the wound or anaesthetic
Cannibalism
Deviation from natural behaviour
Physical injury
More movement (?)
Going through this was a useful exercise. At first I thought the report was making the silly claim of knowing the preferences of shrimps. Actually it’s mostly a much more commonsense “how do we prevent shrimps from dying or getting disease or being physically mutilated.”
Summary
How to improve shrimp welfare:
Don’t cut their eyes off
Aka, “eyestalk ablation”, this is routinely done to female shrimp to increase fertility
“shrimps have a recoil reaction to ablation (Taylor et al., 2004)”
“ablated shrimps were more likely to flick their tails and rub the area of the wound (Diarte-Plata et al., 2012)”
“when the wound was covered or anaesthetic administered, the shrimps reduced these responses”
eyestalk ablation also negatively impacts mortality, biomarkers of stress, and weight loss
Combat disease with protocols regarding disinfection, biosecurity, hygiene, and pond preparation
Slaughter via electrical stunning
“Shrimps are typically slaughtered by either asphyxiation (suffocation) or immersion in ice slurry (chilling) (Weis 2022, at 2min,15sec)”
Electric stunning seems like a more reliable way to quickly render shrimps unconscious.
Only keep 6-15 shrimps per m2
(Note that this number is tentative)
Shrimps tend to distance themselves at high density (Da Costa et al. 2016)
High stocking density is associated with:
Difficulty accessing feed
Reduced water quality (dissolved oxygen, un-ionised ammonia, water hardness)
Increased disease
Increased mortality
Physical injury
Cannibalism
Increased serotonin (stress biomarker)
More frequent movement (stress related?)
At densities below 6 shrimps/m2, “dominance hierarchies become more prominent, and feed consumption diminishes due to the absence of social cues (Bardera et al., 2020)”
Fish studies have also shown negative effects of very low density
Enrich environments
Including “feeding methods that mimic natural behaviours, hiding sites, different tank shapes and colours, plants, substrates, and sediments.”
“In the wild, decapods spend much of their time sheltering in the dark, and should therefore be given access to dark environments (Birch et al., 2021, p.70).”
For fish environmental enrichment has led to “increased social interaction, less abnormal behaviour, and reduced captivity-related stress (Arechavala-Lopez et al., 2022)”
“For L. vannamei maturation tanks, tanks with dark backgrounds and rounded shape are recommended (FAO, 2003, p.22). ”
Improve handling practices
Reduce injury from trawling (fishing by pulling net behind a boat)
Imposing maximum packing weight to prevent shrimps from being crushed and not suffocating (hypoxia)
Improve nutrition
Inadequete nutrition leads to soft shell syndrome, aggression, cannibalism
“Overfeeding, on the other hand, may lead to the build-up of toxic ammonia (Alune, 2020) and increased turbidity”
Improve water quality
Dissolved oxygen between 5 and 8 mg/L.
Un-ionised ammonia <0.05 mg/L
pH of 7.8 to 8.2
temperatures of 28-30°C
salinities between 0.5‰ and 45‰
The report focused on whiteleg shrimp “due to the scale and intensity of farming (~171-405 billion globally per annum) (Mood and Brooke, 2019)”
I tried to extract out the key data because I was wondering how anyone can know what shrimp like. They’re simple alien creatures.
It seems like the presence of these factors are used to indicate “this is bad for shrimps”:
Mortality
Disease
Stress biomarkers (eg serotonin)
Recoil reflex (ie, eyestalk ablation)
An injury-rubbing behaviour that diminishes with covering the wound or anaesthetic
Cannibalism
Deviation from natural behaviour
Physical injury
More movement (?)
Going through this was a useful exercise. At first I thought the report was making the silly claim of knowing the preferences of shrimps. Actually it’s mostly a much more commonsense “how do we prevent shrimps from dying or getting disease or being physically mutilated.”