COMPARISON OF SCALES, OPERCULAR BONES, AND VERTEBRAE TO DETERMINE AGE AND POPULATION STRUCTURE IN TENCH, TINCA TINCA (L. 1758) (PISCES, TELEOSTEI)

ABSTRACT

Samples of tench. Tinca tinca (L., 1758), were taken from Lake Vegoritis, northern Greece (40°45′N, 21°47′). Fish age was determined by comparing different skeletal elements (i.e., scales, opercular bones, and vertebrae). Determination of age from the scales resulted in an overestimation of 1 year in 1.9% and an underestimation of 1 year in 3.2% of the cases when compared to age as determined from opercular bones. In the opercular bones of older specimens, the first and some of the second annuli were not easily discernible. A comparison of readings derived from vertebrae and opercular bones revealed that age determined from vertebrae was both overestimated and underestimated by the same percentage (2.5%). Consequently, using scales to determine age in tench is not recommended for inexperienced researchers, unless the annual rings for ages ≥3 years, are compared with those of the opercular bones and vertebrae.