Scripps Student Spotlight: Jack Elstner

Biological oceanography PhD student is passionate about science that supports marine conservation in a changing ocean

Jack Elstner is a third-year PhD student at Scripps Institution of Oceanography at UC San Diego, where he is studying biological oceanography and fisheries science. Originally from Annapolis, Md., Elstner attended Cornell University, receiving a bachelor’s degree in earth and atmospheric sciences with minors in marine biology and climate change. At Scripps, Elstner is advised by marine ecologist Brice Semmens, and he is the recipient of an NSF Graduate Research Fellowship


Elstner holding a fish during a summer sampling trip for the California Collaborative Fisheries Research Program.

explorations now (en): Why did you choose to attend Scripps?

Jack Elstner (JE): When searching for graduate school programs, I was interested in pursuing a degree that allowed me to blend fisheries science, oceanography, and marine resource management. I am particularly passionate about science that supports marine conservation in a changing ocean and fosters connections between scientists, environmental managers, and users of marine resources. I chose to attend Scripps because of our community’s commitment and dedication to research that is collaborative, interdisciplinary, and solution-based.


en: What are you researching at Scripps?

JE: My PhD research focuses on the ecology, conservation, and management of coastal fishes and sharks in Southern California. In the Semmens Lab, we develop monitoring programs and modeling frameworks that enhance our ability to collect and analyze fisheries data with the ultimate goal of informing fisheries conservation and recovery. A majority of my dissertation work focuses on how we can use collaborative citizen science to evaluate the performance of California’s network of marine protected areas (MPAs).

A drone shot taken by the California State University, Long Beach (CSULB) Shark Lab during a juvenile white shark tagging trip. Photo credit: CSULB Shark Lab.

I currently lead the San Diego sector of the California Collaborative Fisheries Research Program (CCFRP), a state-wide partnership among fisheries scientists, state and federal management agencies, and local fishing communities. Using standardized hook-and-line surveys with rod-and-reel tackle, we generate the information needed to evaluate and adaptively manage marine protected area (MPA) performance. The data we collect allows for comparisons of fish size, relative abundance, and catch composition between MPAs and nearby reference sites. This provides critical insights into how fish communities respond to MPA establishment. Our efforts also directly involve recreational anglers in the science of MPA assessment, which broadens participation in the data collection process and builds trust between researchers and local communities. 

The Semmens Lab has also teamed up with the California State University, Long Beach (CSULB) Shark Lab to study the growing number of juvenile white sharks in Southern California. In recent years, San Diego has become home to a prominent white shark nursery, which has sparked conversations over conservation, fisheries management, and public safety. To understand what these sharks are doing and why they are there, we tag sharks with acoustic transmitters, which are detected by stationary arrays of moored acoustic receivers. The data we collect allows us to define shark activity centers, highlight critical habitats, and understand how sharks interact with different features of their local environment. The projects I lead use this data to construct fine-scale models of shark movement that link underlying patterns of behavior to the environmental and oceanographic factors that influence them. 


Elstner going on a drive for the course SIOB 274: Natural History Below the Tides. He served as a teaching assistant for the course in Fall 2023. 

en: How did you become interested in science and your field of study?

JE: I grew up on the shores of the Chesapeake Bay and fell in love with marine environments from an early age. As a kid, I spent every minute I could outdoors, fishing for striped bass on the Wye River, mucking through salt marshes, and exploring every cove and creek I could before my skiff’s tiny gas tank ran dry. These experiences left a lasting impact on me and taught me how interesting, beautiful, and valuable our planet's marine ecosystems are. At the same time, I saw first-hand in my own backyard the violent clashes that unfold when the interests of humans and nature grow out of sync: the massive fish kills that plagued the Chesapeake Bay every summer, the dwindling American oyster and blue crab populations decimated by overharvesting and disease, and the sinking island communities consumed by rising tides and increasingly stronger storms. From a young age, I saw that we currently live in a world undergoing massive social and environmental shifts, which will impact the world’s oceans in complex and unpredictable ways. These realizations shaped my environmental consciousness and instilled in me a desire to better understand the problems I was witnessing so that I could become a part of their solutions.


en: What’s life like as a Scripps student? Describe a typical day.

JE: Every day at Scripps is different — that’s what keeps it exciting! Days in the field are spent leading hook-and-line surveys on sportfishing boats or conducting local tagging and diving operations in the La Jolla kelp forest or the wave-swept shores of Torrey Pines and Del Mar. Days in the office are spent reading papers, coding, and writing. The best days are the ones that begin with a long run on the beach and end with a sunset surf. 


en: What’s the most exciting thing about your work (in the field or in the lab)?

JE: The marine ecosystems of San Diego are amazing places to do fieldwork. My favorite part of graduate school so far has been the opportunity to spend a lot of time on the water getting to better understand these environments. Time in the field has its way of grounding me in my work and keeping me connected with the ecosystems I study. 


Elstner with his advisor, Brice Semmens.

en: Are there any role models or mentors who have helped you along the way?

JE: There are far too many to name, however, my advisor, Brice Semmens, has been a particularly influential mentor for me throughout my time in graduate school at Scripps. He’s shown me not only what it means to be a scientist, but also how to balance science with the other important things in life. 


en: What are some challenges you face as a student?

JE: So much to do and so little time! This is a common feeling among graduate students, but I typically can’t shake the experience of staring down a half-done to-do list at the end of every day. Fortunately, I have a phenomenal group of lab mates, collaborators, and peers who always seem to have my back when I come up short. 


en: What are your plans post-Scripps?

JE: After Scripps, I am pursuing a position as a fisheries scientist that allows me to work on projects supporting marine resource management, while also continuing to collaborate closely with local fishing communities. Mentorship and teaching are also really important to me. I hope these things are central aspects of what I do next.


You can find Elstner on Instagram @jackelstner17.

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