Fish Ecology in Pictures

By Mary Alice Hartsock

The staff of the “Fisheries” Section in the Academy’s Patrick Center for Environmental Research can be a little sensitive about their name. They don’t catch or sell fish for commercial purposes, as their label implies, and they are not responsible for managing commercial and recreational fishing.

Still, the name “Ichthyology Department” was already selected as the name for Academy fish scientists studying systematics (the study of the evolutionary relationships of living things and how they’ve changed over time), so “Fisheries” it was. And despite the misnomer, the team has played a role in countless projects that link fish location, diversity, and abundance to the well-being of our waters, our lands, and our future.

Rich Horwitz, PhD, a Drexel professor and Ruth Patrick Chair of Environmental Science at the Academy, refers to his team as “the fish ecologists.” They work in streams, rivers, lakes, and estuaries to understand which fish are where, why they are located where they are, and how people have affected fish location, diversity, and abundance.

One important aspect of the team’s job, Horwitz says, is to determine how human interventions such as habitat disturbance, urbanization, spills, dam removal, and other contamination events affect fish. Their data also can assist in watershed planning, helping to prioritize areas for preservation, assessing the effects of restoration activities, and analyzing the impacts of climate change. Often the team serves as an unbiased source of reliable data for scientific and governmental organizations, such as state environmental protection agencies.

Sometimes agencies want to know whether certain species are declining or endangered, or if invasive species are proliferating. The department maintains extensive fisheries databases that include long-term, continuous assessment data from projects that have been ongoing for over 50 years. They use these databases alongside Ichthyology Department collections and other data sources to analyze environmental trends and changes in biodiversity in rivers and other systems throughout the world.

The following photographs showcase the fieldwork of the Academy’s fish ecology team:

Red Salamander

Academy fish ecologists spotted this red salamander (Pseudotritan ruber) in Bushkill, PA, during research for the Delaware River Watershed Initiative. Salamanders are sensitive to water contamination, and their presence or absence can provide insights into water quality when fish are scarce. Photo by David Keller/ANS

Scientists net fish

In addition to fieldwork and publications, many Academy scientists include teaching on their resumes. A number of young scientists who have worked with our fish ecologists have pursued advanced degrees in the biological or environmental sciences, and many have obtained jobs in government, including in state environmental protection departments. For Drexel University’s Department of Biodiversity, Earth & Environmental Science (BEES), our fish ecologists teach courses, host students in the Academy’s classrooms and laboratories, and take students into the field for real-world application of classroom learning.Academy scientists Rich Horwitz and Paul Overbeck, with co-op students Emily Johnson and Halle Choi and Drexel graduate student Maria Berezin, net fish during the 2014 Upper Delaware BioBlitz.

Woman measures blue gill

A scientist measures a blue-gill found in a small New Jersey stream before releasing it back into its habitat.

Scientists in stream

The Academy was granted three years of funding from the William Penn Foundation for its work on the Delaware River Watershed Initiative, a massive multi-year initiative to protect and restore critical sources of drinking water in the Delaware River Basin. The Academy is working alongside the William Penn Foundation, the Open Space Institute, the National Fish and Wildlife Foundation, and the Institute for Conservation Leadership to provide scientific oversight for the entire project, with more than 40 grantees working to restore degraded areas, protect undamaged areas, and monitor watershed health.

The Academy’s work includes monitoring ecological conditions at over 100 sites across the Delaware Basin. Above, Academy staff and students from Drexel University’s Department of Biodiversity, Earth & Environmental Science don 35-pound backpack electrofishing units to survey Barrett’s Run, a small stream in New Jersey, in June 2014. To understand whether the initiative’s stream restoration and protection activities are improving water quality, they use the units and nets to obtain a complete survey of fish in a given reach of the stream, sampling two to three times to estimate the total abundance of the stream’s various species. Under the guidance of Academy scientists David Keller and Paul Overbeck, students learned to set up block nets and use the electrofishing units to obtain thorough, meaningful samples.

Man in boat

Academy scientist David Keller (in orange) nets flathead catfish as Paul Overbeck steers an electrofishing boat on the Schuylkill River below Philadelphia’s Fairmount Dam. An invasive species first documented in the Schuylkill in 1997, flathead catfish have spread throughout the Delaware River drainage. Academy scientists have worked to determine where these catfish are located and at what times of year they are prevalent to gather data on how they impact the local ecosystem.


Keller, Overbeck, and other Academy fish ecologists sample fish, salamanders, and crayfish and record information about their habitats. They spotted this longtail salamander (Eurycea longicauda) near Limerick in Montgomery County, Pennsylvania.

This article originally appeared in the summer 2015 issue of Academy Frontiers

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