What does this temperature stratification mean for yabbies?
The temperature of the deeper water in dams is not very favourable for yabbies. The water under the thermocline is usually about 14oC at the start of hotter spring weather and warms to only 19oC by the end of summer. Above the thermocline, the water heats and cools daily in the range 20oC to over 30oC (they can tolerate temperatures up to 36oC). Yabbies grow most rapidly in the range 24oC to, a maximum at, 28oC and below 20oC growth slows down to a halt below 15-16oC. These facts mean that there is only a relatively small area of the bed of a dam, under shallow water around its edges, which is likely to have the most favourable temperatures for growth of yabbies during summer.
