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Against the Current – Quantifying Threats Facing Threatened and Endangered Fish Taxa

by Delaney Costante


The aim of this study was to analyze threats facing fish taxa protected under the U.S. Endangered Species Act. Utilizing species’ federal listing documents, we developed a database of identified threats to threatened and endangered (T&E) fish species based on six general groups: Habitat Destruction/Modification, Overutilization, Pollution, Species-Species Interactions, Environmental Stochasticity, and Demographic Stochasticity. For our analysis, fish were divided into freshwater and diadromous/marine groups. Threats to fish were also compared with threats impacting other vertebrate taxa (e.g., amphibians, birds, mammals, and reptiles). We found that pollution impacted freshwater fish (57.8%) and amphibians (45.8%) more than other groups of taxa (10.5-31.4%), and overutilization impacted diadromous/marine fish (91.1%) and reptiles (51.4%) more than other groups of taxa (6.0-29.2%). Other threats were similar among all vertebrate taxa. Fish taxa were susceptible to threats resulting from human consumption, be it overharvest of diadromous/marine fishes or the majority of pollutants harming freshwater T&E fishes coming from agriculture (fertilizers, pesticides, herbicides, etc.). A growing human population size with an increased appetite appears to be causing fish species to require federal protection to prevent extinction.

About the Author

Delaney is currently a junior majoring in Biology with concentrations in Marine and Environmental biology. For as long as she can remember, Delaney has been passionate about marine life (especially sharks) and has wanted a career studying and conserving these fascinating creatures. When she began her Endangered Species Act (ESA) research, of which this presentation is a subproject, it was an exciting opportunity as an undergraduate to begin work which would have significant implications for conservation. The project as a whole seeks to identify which threats were facing U.S. Threatened and Endangered species protected by the ESA at the time of their listing. This is determined by reviewing Final Listing Documents of all species, from 1973 through today. This data is used to compare how threats have changed over time, whether different threats are more detrimental to different taxa, and to identify hotspots of where human activity is having the largest impact on wildlife. In the near future, Delaney hopes to attend graduate school and go on to a career in bioacoustics research with Chondrichthyes. The opportunity to participate in this research has been a great learning experience as well as a great way for her to begin to make a positive environmental impact.

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