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Geology topics

David H. Secor

Publications and source records attributed to David H. Secor.

3 recordsLinked to original sources

Stock composition of the historical New York Bight Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) intercept fishery revealed through microsatellite analysis of archived spines

A targeted commercial fishery for Atlantic Sturgeon Acipenser oxyrinchus oxyrinchus once operated in the New York Bight, where it was assumed that most harvested Atlantic Sturgeon were natal to the Hudson River population. However, more recent evidence suggests that the fishery may have been targeting a mixed-stock aggregation, in which case harvested Atlantic Sturgeon could have been comprised of individuals from multiple populations throughout the species’ range. Although there is now a moratorium on Atlantic Sturgeon harvest in the New York Bight, modern molecular approaches provide an opportunity to use archived tissues to perform a retrospective mixed-stock analysis on the fishery. Genomic DNA extracted from archived fin spines from 80 Atlantic Sturgeon collected nearly 30 years ago suggests that the fishery primarily harvested individuals from the Hudson River population. However, based on individual-based assignment tests, our results indicate that the fishery also harvested individuals from at least eight other populations located throughout the species’ range. This study highlights how archival hard parts that were previously used for age and growth analyses can be employed for retrospective genetic analyses. Further, because the New York Bight harbors relatively high concentrations of Atlantic Sturgeon, the study shows how localized management decisions can influence Atlantic Sturgeon conservation at rangewide scales. When integrated with more recent knowledge of species ecology, these analyses can be used to evaluate the efficacy of previous management strategies and understand the effects of historical processes on contemporary demography.

New York

Population connectivity of pelagic megafauna in the Cuba-Mexico-United States triangle

The timing and extent of international crossings by billfishes, tunas, and sharks in the Cuba-Mexico-United States (U.S.) triangle was investigated using electronic tagging data from eight species that resulted in >22,000 tracking days. Transnational movements of these highly mobile marine predators were pronounced with varying levels of bi- or tri-national population connectivity displayed by each species. Billfishes and tunas moved throughout the Gulf of Mexico and all species investigated (blue marlin, white marlin, Atlantic bluefin tuna, yellowfin tuna) frequently crossed international boundaries and entered the territorial waters of Cuba and/or Mexico. Certain sharks (tiger shark, scalloped hammerhead) displayed prolonged periods of residency in U.S. waters with more limited displacements, while whale sharks and to a lesser degree shortfin mako moved through multiple jurisdictions. The spatial extent of associated movements was generally associated with their differential use of coastal and open ocean pelagic ecosystems. Species with the majority of daily positions in oceanic waters off the continental shelf showed the greatest tendency for transnational movements and typically traveled farther from initial tagging locations. Several species converged on a common seasonal movement pattern between territorial waters of the U.S. (summer) and Mexico (winter).

Scientific Reports

Assessing dorsal scute microchemistry for reconstruction of shortnose sturgeon life histories

The imperiled status of sturgeons worldwide places priority on the identification and protection of critical habitats. We assessed the micro-structural and micro-chemical scope for a novel calcified structure, dorsal scutes, to be used for reconstruction of past habitat use and group separation in shortnose sturgeon ( Acipenser brevirostrum ). Dorsal scutes contained a dual-layered structure composed of a thin multi-layered translucent zone lying dorsally above a thicker multi-layered zone. Banding in the thick multi-layered zone correlated strongly with pectoral fin spine annuli supporting the presence of chronological structuring that could contain a chemical record of past environmental exposure. Trace element profiles (Sr:Ca), collected using both wavelength dispersive electron microprobe analysis and laser ablation inductively coupled mass spectrometry, suggest scutes record elemental information useful for tracing transitions between freshwater and marine environments. Moreover, mirror-image like Sr:Ca profiles were observed across the dual-zone structuring of the scute that may indicate duplication of the microchemical profile in a single structure. Additional element:calcium ratios measured in natal regions of dorsal scutes (Ba:Ca, Mg:Ca) suggest the potential for further refinement of techniques for identification of river systems of natal origin. In combination, our results provide proof of concept that dorsal scutes possess the necessary properties to be used as structures for reconstructions of past habitat use in sturgeons. Importantly, scutes may be collected non-lethally and with less injury than current structures, like otoliths and fin spines, affording an opportunity for broader application of microchemical techniques.

Environmental Biology of Fishes