Wednesday, June 29, 2011

Sexing Crayfish / Crawfish

During mating the male red claw will attach a spermatophore (sack containing sperm) to the underside of the female between the third and fifth pair of legs. The spermatophore is white and about 1/3 inch in diameter.
Within 24 hours the female usually releases eggs from the pore on the base of the third pair of walking legs. These eggs are fertilized by the spermatophore as they are released. Female red claw, like native crayfish, attach the eggs to the swimmerets under their tail or abdomen. The eggs remain attached through the incubation period. The incubation period may last 4 to 6 weeks depending on water temperature. At 82oF the incubation period averages 30 days. Individual eggs are oval and about  1/10 of an inch in diameter. Females carrying eggs are called “berried” females. Berried females are easily recognized because they tightly curl their abdomen under the body for the first 10 to 14 days after spawning. They are also less active during this period. Berried females should be moved to separate spawning tanks so that the young hatchlings do not have to be captured from the broodstock tanks. Broodstock tanks should be checked for berried females at three to four week intervals.
Berried females must be carefully netted and transferred to hatching tanks (to prevent egg loss).  Keep
the berried females with their abdomen curled around the eggs during transfer to prevent eggs
from being dislodged by tail movements.

Source : Southern Regional Aquaculture Center / SRAC Publication No. 244 April 1997

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