Striped Bass eggs and larvae in the Miramichi River estuary: a resource pulse detectable only with molecular tools?

Spawning events can provide resource pulses that can fuel food webs when other resources are limited, yet their utilization by fish communities is poorly understood. We combined traditional visual examinations and qPCR analysis of stomach content DNA (scDNA) to evaluate consumption of Striped Bass ( Morone saxatilis) eggs and larvae by 21 fish species collected before and during the Striped Bass spawning period in the Northwest Miramichi River estuary. Striped Bass was present throughout the study, with higher catches coinciding with peak eggs and larvae densities, which was a better predictor of scDNA compared to catches of Striped Bass. Visual inspection revealed eggs in only one American Eel ( Anguilla rostrata), whereas scDNA showed widespread increases in detections during spawning compared to the pre-spawning period, suggesting that Striped Bass reproduction generated a detectable community-level resource pulse. This study reveals hidden pathways of energy flow not detectable through traditional methods, emphasizing the value of molecular tools for resolving cryptic trophic interactions. These findings advance understanding of the ecological role of Striped Bass spawning for the fish community of the lower Northwest Miramichi River and provide novel insights into the detection and understanding of resource pulses associated with spawning events in aquatic ecosystems.