On the Use of Cyprinid Scales in the Diet Analysis of Piscivorous Species: How Much Information Is Hidden in a Fish Scale?

AbstractScales of eight common European cyprinid species were studied. Six scales were extracted from each specimen from three predetermined body areas. The main differences among the species' scales were described. Maximum and minimum lateral radius and maximum length were measured, and the number of radii noted. The relationships between standard length and scale measurements were best described by power functions, and maximum length showed the best fit in most of the analyzed cases. Scales from different body areas showed significant differences in body length estimates. The number of radii increased with age in all species, except for goldfish Carassius auratus, roach Rutilus rutilus, and rudd Scardinius erythrophthalmus. This number might be related to the general activity of the fish or to environmental conditions. Much information can be obtained from scales, but it should be interpreted with care. Detailed and precise scale studies are needed for diet analyses and piscivorous impact evaluation.