Naupliae as well as sub-adults or adults can be inoculated. Inoculated naupliae will first have to grow to the adult size before population growth can start. Sub-adults inoculation will result in faster effect and is safer in cases where especially temperature conditions are on the tolerance limit (36 – 37°C). However adult inoculation requires first high density culturing in separate tanks.
Inoculation with cysts will not work since cysts can not hatch in salinities of 100–110 ppt.
After determination of the number of naupliae needed, the corresponding amount of cysts to hatch can be calculated from the hatching efficiency of the used strain. (see practical work sheets). The hatching efficiency is the weight of cysts (gram product) needed to produce one million naupliae.
Naupliae inoculation densities are usually in the range of 30–100 naupliae per liter pond water. This allows some mortality of the naupliae after inoculation.
Hatching of the naupliae is done according to the instructions in the practical work sheets.
If inoculation can be performed at the inoculation site itself (electricity available or battery-operated aerators), no special transportation methods have to be used. Naupliae can be carried to the pond in densities half the hatching density.
After hatching transfer the naupliae to containers with the same salinity as the pond water. They survive the shock. For adults salinity change should be done more gradually.
If hatching can not be done at the inoculation site, naupliae will have to be transported in the following manner:
Collect and sieve naupliae, and transfer them to the appropriate salinity of the pond.
Rinse with 0–4°C salt water and transport them in cold brine at a density of 10 million/20 liter (equivalent to 50 g cysts/20 liter). Motoric activity will stop and they will tend to sink to the bottom. Therefore provide slow aeration from the bottom of the container to keep the animals in suspension. Use styrofoam and ice to keep temperature low, during transportation. Instead of containers, also plastic bags inflated with oxygen can be used.
Adults and sub-adults can be transported in the same way at densities of 20,000 animals per liter.
The best time of the day to inoculate a pond is during late evening since at this time water temperature is low and will continue to drop till early morning. If this is impossible, inoculate in early morning.
Although naupliae as well as adults can be transferred directly from their low temperature transportation containers into the inoculation ponds, it is safer to first let temperature in the containers rise a little so that the animals can resume motoric activity.
The first days after inoculation it might be very difficult to find or see any of the inoculated naupliae. They lost their distinctive orange color (no more yolk) and they tend to gather in corners of the pond. When inoculation is successful, the first sub-adults should be seen swimming after a week or less.
