Validation of the ageing of 0+ carp (Cyprinus carpio L.)

Forty carp larvae were reared from eggs spawned in the Torrens River, Adelaide, South Australia, and their otoliths were examined at the time of hatching or at 6, 10, 15 or 20 days after hatching (post-hatch). Using light- and scanning electron microscopy (SEM), otolith increments were counted and compared with known post-hatch ages. Typically, the counts were one day (range 0–2 days) more than the known post-hatch age, but increment formation was daily to at least age 20 days. Thus, age estimates derived from otolith increment counts of wild-caught 0+ carp should be reduced by one day. Comparison with SEM data showed that light microscopy alone offers sufficient resolution for ageing 0+ carp.Benjamin B. Smith and Keith F. Walke