GASTRIC EVACUATION RATES OF PISCIVOROUS YOUNG-OF-THE-YEAR BLUEFISH

Estimates of gastric evacuation rates (GER) are needed to calculate co nsumption rates of fish from field-collected data on stomach contents. The results of 16 GER experiments designed to determine the effects o f body size, prey type, and temperature on the GER in young-of-the-yea r (age-0) bluefish Pomatomus saltatrix are presented. The linear, squa re-root, and exponential GER models similarly fit the data. Temperatur e had a highly significant effect on age-0 bluefish GER. However, ther e was no significant difference in GER between small (5.14 g wet weigh t) and large (35.99 g wet weight) age-0 bluefish. Among the three diff erent prey types tested (age-0 striped bass Morone saxatilis, bay anch ovy Anchoa mitchilli, and age-0 Atlantic menhaden Brevoortia tyrannus) there was no significant difference in GER. The exponential relation between bluefish GER and temperature can be used in estimating age-0 b luefish consumption rates in the field.