Relationships between sagittal otolith length and fish size for 14 mojarra species (Gerreidae: Perciformes) in Mexico

The relationships between fish length and weight and sagittal otolith length have not been studied in many families of fish that inhabit the coastal waters of Mexico, such as the Gerreidae family. Fish in this family are a valuable local fishery resource in Mexico and important prey for higher trophic level piscivores. The relationships between fish length and weight and otolith length were investigated for 14 species of Gerreidae. The relationship between fish length and otolith length was linear (r² ≥ 0.83 for 12 of 14 species; 0.87 mean), while the relationship between fish weight and otolith length was exponential (r² ≥ 0.85 for 11 of 14 species; 0.88 mean). Mean percent prediction errors (mPPE), which indicate the strength of individual bivariate relationships, were 5.6% for otolith length against fish length and 12.9% for otolith length against fish weight. Hence, predictive regression equations developed herein can be used to back-calculate the size and weight of prey from recovered otoliths. Several factors can limit the back-calculation of parameters based on otolith length; however, the present results indicate that accurate predictions are possible. Nevertheless, regression equations should not be applied to fish and otoliths beyond the size range examined.