Carl Shuster Q&A

In the scientific community, you can’t talk about horseshoe crabs without hearing mention of Dr. Carl Shuster’s name. He has studied them since 1947. While a blip on the map in the history of these ancient creatures, that’s a long time in the world of science.  In May 2000, he recommended to the Atlantic States Marine Fisheries Commission that a sanctuary be established to protect juvenile and adult females from commercial over-harvesting at that time. A year later, the National Marine Fisheries Service established the 1,500-square mile “Carl N. Shuster, Jr. Horseshoe Crab Reserve,” a no-take area located at the mouth of the Delaware Bay. Since then, the sanctuary has welcomed huge aggregations of increasingly healthy horseshoe crab populations each year. Now based in Arlington, Virginia, Dr. Shuster shares some wisdom from more than six decades of study.
“Currently, the Delaware Bay represents the perfect combination of factors necessary for supporting horseshoe crabs.”

Dr. Carl Shuster, Horseshoe crab expert

What sparked your interest in horseshoe crabs?

Dr. Shuster:

Happenstance. A professor with whom I studied prior to World War II remembered I had an interest in birds. He handed me a jar of horseshoe crab eggs and said, “Study these, birds love them.”

How soon after that did you discover the Delaware Bayshores?

Dr. Shuster:

A couple of years later, during the spring of 1949. The same professor brought me to an area where horseshoe crabs were spawning. It was during high tide on a very calm day. You could hear the click-clack of shells bumping against each other – kind of like castanets. What looked like rocks bobbing in the waves, were actually crabs. It was quite an experience.

Is that when you began focusing your studies on these creatures?

Dr. Shuster:

Yes. I learned that I might have a knack for studying them. I observed things my professor hadn’t considered, and that hadn’t been studied. For example, rough waves during a storm swept unattached males away from spawning females. It showed a clear advantage for males attaching to females. Also, female horseshoe crabs won’t spawn unless they are attached. After that, I had the opportunity to break lots of new ground – almost uninterrupted for 25 years – because it wasn’t a very interesting topic at the time. That’s changing with new land development patterns and issues like climate change.

Since capturing your attention, it seems that no matter where you worked and lived, you’ve always returned to the Delaware Bay.

Dr. Shuster:

That’s true. Early on, I spent a summer in Cape May. Later, I spent eight years working at the University of Delaware. After that, I visited off and on regardless of where I was based. I’ve continued spending part of each summer there since retiring in 1984.

What makes the Delaware Bayshores so special in regard to your work?

Dr. Shuster:

Currently, the Delaware Bay represents the perfect combination of factors necessary for supporting horseshoe crabs. It wasn’t always that way. Over their long history, horseshoe crabs have migrated to favorable areas. Before the last ice age, they didn’t live much further north than Florida. For about 5,000 years however, the Delaware Bayshores has represented a favorite spot for horseshoe crabs. It boasts an ideal climate and long, sandy beaches for spawning. Shallow waters support the development of young crabs. Deeper waters offshore offer a place to rest and feed on a rich assortment of marine worms, blue mussels and surf clams. The combination of all these factors – tidal marsh, sandy beaches, shallow water and the continental shelf – make conditions in the Delaware Bayshores just right.

In you opinion, what’s the future look like for horseshoe crabs in the Delaware Bay area?

Dr. Shuster:

Currently bright, if we can stay the course. However, it’s unpredictable. Events like beach erosion, severe storms and human development are rapidly changing the landscape. For example, a recent storm significantly eroded beaches and destroyed and dunes. These events undoubtedly have an impact on spawning.

What can be done?

Dr. Shuster:

To continue supporting these species, we need to recognize what’s right with our current management and work to keep the life cycle operating correctly. The only way to make sure we don’t lose all of our beaches is to artificially replenish them. So we have to encourage neighboring state governments to restore their beaches. In addition to restoring beaches, we can also explore other management practices, and just leave some lands and waters alone. It’s all a work in process.

Speaking of a work in progress, what’s next for you and these crabs?

Dr. Shuster:

I continue to visit the Delaware Bayshores each summer. I spend some of that time teaching educators about horseshoe crabs. I also take time for observation. Lately I’ve been exploring methods of determining horseshoe crab age by appearance as a way of getting a handle on population trends. Looking for clues like spawning scars and the shininess of a shell can be difficult to do during evening surveying. However, if surveyors can take some photos, maybe I can help. A lot of people are studying horseshoe crabs and their unique habitat. It’s an exciting time for the science and I just can’t stay away.


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