Get to know the Koura. Biological information.
The freshwater crayfish genus “Paranephrops” is native to New Zealand only. They're similar to other small crayfish species found world-wide. Cute little crayfish with souls (self-aware minds) created by the eternal God of Israel.
There are zero koura recorded in the Whakatane (Tamahine-a-Hine-Mataroa River) and the Waioeka-Gorge Rivers, But there are koura recorded in the Motu and Rangitaiki River systems.
A crayfish's size is most commonly measured as Total Carapace Length (TCL). The TCL is the distance from the tip of its nose (rostrum) to the "top" end of the carapace. (The "carapace" is the cylindrical shell that goes around the crayfish's back and stomach.)
Measure from the top of the Crayfish's back 'carapace' shell, exactly from the line between the back-shell and the start of the first tail segment's shell.
In insular communities, Males and females grow at the same rates. Though males are bigger
Food availability (the amount of food eaten daily) proportionally correlates to Body size of maturity.
Water temperature affects time of maturity. So this means that if there is lots of crayfish in tank then what affects them is the availability of food.
Water temperature for Paranephrops planiforns needs to be below 24* C .
Water needs 10mg/L of oxygen (oxygenated water).
Food availability per capita regulates both body-size and fecundity (brood size). Thus brood size(egg/baby population) is indicator of body-size(length.)
In natural environments, when Crayfish population is high, and human-overfishing happens reducing population then there is an increase in food for the Crayfish, and fecundity increase to compensate.
While the natural heterogeneity causes natural populations to have fast-maturing and slow-maturing creatures, selective breeding inadvertently changes the genotypes of the population.
First fries. (humans select the very first babies of the earliest parents, to reproduce. )
Pristine populations would have had relatively fewer ‘larger’ females.
The nineteenth-century saw reduction in biodiversity due to brown-trout introduction.
Long-finned eels and brown trout are predators of koura. Crayfish in the wild can detect the skin-mucous of predators like brown-trout and eels. (So don’t keep both predator and prey in the same tank.)
Wild Koura hide under ‘see through’ cover in presence of predators (smell and physically).
• Koura swim when scared of physical native eels (not mucous nor Chem-Cues All-Cues trout).
• Koura don’t eat when scared & aware of predators, but will eat if eel-mucous is present. (incentive to eat.)
• Koura stand in upright (up on hind legs with front “chelae” upward and forward (fists up).
• Crayfish walk freely (often) when no trace of predators.
• Crayfish maybe learn from experience or evolutionarily innate responses. This is how evolution destroys common sense, by masking the intelligence of an animal with a soul, into millions of years of ‘honed’ chemical reactions. (the crayfish reacts to eel slime) rather than (the crayfish learnt from it’s time in the wild what is an eel).
1. Talk to local kaumatua about their memories and matauranga(knowledge) of koura.
2. Learn about ecology and “environmental whakapapa of system”
a. Pick best areas with clean water, low fine sediment
b. Assess adjacent land use (need for fences), and local wildlife (i.e: eels, whitebait, flies, snails, smelt).
| Page Contents: | |||
| Locality | Food | Body size | Water qualities |
| Breeding | Anti-predator behaviour | Cultural considerations | Shops & Economics |
Locality within New Zealand
Koura are “not threatened” (being found in %20 of sites). Species_surveys taken in Lake Okoru produced 0 sample size, and lake Rewawhakaaitu caught koura for survey of 70 sample size.There are zero koura recorded in the Whakatane (Tamahine-a-Hine-Mataroa River) and the Waioeka-Gorge Rivers, But there are koura recorded in the Motu and Rangitaiki River systems.
“It is envisaged that kōura in the inflowing tributary will provide a source of recruitment for the lakes when water quality conditions improve.” Better not interfere with their scientific research into water quality."
It is important to check with NIWA before releasing animals into the wild. You must check The NIWA wildlife surveys for if your neighbourhood river has historically had Koura before life-releasing your excess koura babies into the wild.
Body length, and muturity
Measuring a Crayfish's size.
A crayfish's size is most commonly measured as Total Carapace Length (TCL). The TCL is the distance from the tip of its nose (rostrum) to the "top" end of the carapace. (The "carapace" is the cylindrical shell that goes around the crayfish's back and stomach.)
Measure from the top of the Crayfish's back 'carapace' shell, exactly from the line between the back-shell and the start of the first tail segment's shell.
How exactly crayfish grow.
Crayfish increase in size (length) incrementally (from moult event to moult event) with each shell moult. When they moult, they store calcium in little pearls before moulting, and re-absorb the pearls to form the shell.In insular communities, Males and females grow at the same rates. Though males are bigger
Food availability (the amount of food eaten daily) proportionally correlates to Body size of maturity.
Water Quality
Water temperature
Water temperature affects time of maturity. So this means that if there is lots of crayfish in tank then what affects them is the availability of food.
Water Temperature
Water temperature for Paranephrops planiforns needs to be below 24* C .
Water needs 10mg/L of oxygen (oxygenated water).
Breeding
Size-related fecundity.
Annual egg production and egg-size depend on the crayfish's body-size.Food availability per capita regulates both body-size and fecundity (brood size). Thus brood size(egg/baby population) is indicator of body-size(length.)
In natural environments, when Crayfish population is high, and human-overfishing happens reducing population then there is an increase in food for the Crayfish, and fecundity increase to compensate.
Effect of human-selective breeding
While the natural heterogeneity causes natural populations to have fast-maturing and slow-maturing creatures, selective breeding inadvertently changes the genotypes of the population.
First fries. (humans select the very first babies of the earliest parents, to reproduce. )
Pristine populations would have had relatively fewer ‘larger’ females.
Anti-Predator behaviour.
The nineteenth-century saw reduction in biodiversity due to brown-trout introduction.
Long-finned eels and brown trout are predators of koura. Crayfish in the wild can detect the skin-mucous of predators like brown-trout and eels. (So don’t keep both predator and prey in the same tank.)
Wild Koura hide under ‘see through’ cover in presence of predators (smell and physically).
• Koura swim when scared of physical native eels (not mucous nor Chem-Cues All-Cues trout).
• Koura don’t eat when scared & aware of predators, but will eat if eel-mucous is present. (incentive to eat.)
• Koura stand in upright (up on hind legs with front “chelae” upward and forward (fists up).
• Crayfish walk freely (often) when no trace of predators.
• Crayfish maybe learn from experience or evolutionarily innate responses. This is how evolution destroys common sense, by masking the intelligence of an animal with a soul, into millions of years of ‘honed’ chemical reactions. (the crayfish reacts to eel slime) rather than (the crayfish learnt from it’s time in the wild what is an eel).
community guidelines to help Maori society replenish the environment.
what we can do to increase Koura.1. Talk to local kaumatua about their memories and matauranga(knowledge) of koura.
2. Learn about ecology and “environmental whakapapa of system”
a. Pick best areas with clean water, low fine sediment
b. Assess adjacent land use (need for fences), and local wildlife (i.e: eels, whitebait, flies, snails, smelt).
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