Acoustic Telemetry Validation of Atlantic Sturgeon Dorsal Scute Microchemistry: Complementary Tools to Reconstruct Life-History of an Endangered Species.

Ingram, Evan*¹, Matthew Altenritter², Kylee Wilson², Michael Frisk¹, Kellie McCartin³, ¹Stony Brook University, Stony Brook, NY, ²The College at Brockport, State University of New York, Brockport, NY, ³Suffolk County Community College, Riverhead, NY

Sampling and microchemistry analysis of dorsal scute apical spines (DSAS) represents an innovative methodology to reconstruct past life-history events of endangered Atlantic Sturgeon (Acipenser oxyrinchus oxyrinchus). Dorsal scutes are calcified structures that may exhibit chronological layering and contain a chemical record of past environmental exposure. These structures hold the potential to elucidate the timing of past life-history events such as recruitment into marine environments or subsequent migrations between marine and riverine waters for feeding or spawning purposes. Here, we establish the broad potential of DSAS sampling for wild-caught Atlantic Sturgeon and demonstrate the congruence of age-estimates and trace-element ratio patterns obtained from these structures and pectoral fin spines (PFS). We also evaluate microchemistry signatures from both structures to infer past habitat use and age at initial entry into marine waters. Importantly, we use known locations derived from acoustic telemetry detections to validate our interpretations of habitat use. Major ontogenetic shifts in habitat use detected in the microchemistry signatures from both DSAS and PFS suggest our methodology appropriately identified the timing of initial juvenile migration into marine habitat. Transects from the DSAS were approximately three-times shorter than those of the PFS, while providing similar estimates of age and the timing of critical life-history transitions. This suggests DSAS collection is more practical for large-scale or batch microchemistry analysis and may be preferred over PFS, depending on desired research outcomes. Our results provide crucial information regarding the ontogenetic timing of transitions between freshwater and marine habitats that are essential to the management and conservation of this endangered species. Collection of DSAS samples is suggested to complement ongoing research efforts and provide additional data points beyond those available from conventional tag-recapture methods alone, allowing researchers and managers to resolve broad-scale details on movements and habitat use that occur prior to primary sampling encounters or outside of monitored areas.