124. As with salmon there is the potential for poor welfare during the stripping and milking processes with trout but broodstock management is economically important and care is usually taken with fish handling. Other reproductive techniques such as induced triploidy and all-female production may have an effect on welfare but this is not known at present.
125. Most broodstock are two to five years old. They are valuable and are housed in conditions better than those for fish destined for slaughter. Spawning is seasonal with some stocks maturing in autumn, others in spring. Fish are examined for maturity by handling with or without anaesthesia. On ovulation, eggs drop into the abdominal cavity. They are hand stripped from the hen fish by gentle stroking of the abdomen from head to vent once the fish are fully anaesthetised. When stripping is complete, the hens are returned to a pool where they slowly recover from anaesthesia.
126. Males may be stripped of milt in a similar way but sex-control practices, now commonly used, require that the fish are humanely killed (see paragraphs 250-253) prior to surgical removal of the gonads. A range of anaesthetics is used to calm the fish before handling. Most operators use rough guidelines for concentrations modified by the way fish respond on the day and dependent on environmental factors.