Effect of Brooder Age and Size on Fry Size Variation in Channel Catfish

Abstract

AbstractVariation in harvest size of ictalurid catfishes can be problematic for both catfish producers and processors, ultimately reducing profitability for both. Although harvesting and grading techniques can reduce this variation, the biological underpinnings of these size discrepancies remain unknown. Fry from Channel Catfish Ictalurus punctatus brooders that were 2–5 years old were measured to determine the amount of naturally occurring variation in body mass among sac fry and swim‐up fry. Over two spawning seasons, older brooders consistently produced larger sac fry (38–54% larger) and swim‐up fry (42–51% larger) than their younger counterparts. However, within‐spawn fry size variation was similar among all brooder ages measured. Regression modeling indicated that broodstock body mass did not influence fry body mass, whereas broodstock age was a significant predictor. These data reveal that brooder age is an important determinant of fry size and that initial fry body mass variation could be relevant to understanding fingerling size variation and may play a role in improving the production of ictalurid catfishes.