Another use of genetic data is to check culture populations for the effects of
inbreeding, which may ultimately lower production levels. High levels of inbreeding
can cause increased mortality, abnormal development or other unwanted characteristics
such as lowered resistance to disease. One study surveyed allozyme variation in
Procambarus clarkii and found lower levels of genetic variation in individuals raised in
aquaculture ponds compared to those from wild populations, suggesting potentially
higher levels of inbreeding in an aquaculture setting (Busack, 1988). Genetic data may
also be useful in the selection of brood stocks (Fetzner et al., 1997). Many areas starting
up aquaculture activities are importing crayfish from around the world, but many find
that these exotic crayfish do not fare well in new areas. Presumably, this is due to
environmental differences between the native and introduced habitats. The genetic data
can be used to choose among different potential stocks which possess traits or markers
that are compatible with environmental situations in the area of