Who eats the most Maryland blue crabs every year? Spoiler: It’s not people.
· Yahoo News- Smithsonian researchers found that older blue crabs are the main predators of young blue crabs in the Chesapeake Bay, with cannibalism accounting for over 97% of predation.
- Fish predation on young blue crabs in the bay was not observed, with the main threat coming from larger crabs that feed by pushing their claws into the muck or sand where the juveniles hide.
- Despite human consumption of blue crabs in the Chesapeake Bay, the population has been declining, with the second-lowest dredge count recorded in 2024 at 238 million crabs.
Smithsonian researchers discovered who eats the most young blue crabs in the Chesapeake Bay — it’s not people, or even fish, but bigger blue crabs with a surprising appetite for cannibalism.
And you thought your uncle Danny down the ocean held the record.
They knew cannibalism was a common threat for young crabs, Anson “Tuck” Hines, lead author and a former scientist at the Smithsonian Environmental Research Center in Edgewater, told Scientific American.
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“What was surprising was that we found here no fish predation — not a single instance of fish predation,” he said. “All the predation was due to cannibalism by other crabs.”
The center spent 37 years monitoring who eats young blue crabs. They found that where and how deep the juveniles hid made a big difference. In the main brackish part of the Bay, between the freshwater of the Susquehanna River and the salty Atlantic, their biggest predator was older crabs. Invasive blue catfish prefer the freshwater upstream, and predatory saltwater fish stay near the mouth of the bay.
Crabs are the dominant predator on the bottom of the bay, the Smithsonian researchers wrote, and frequently feed by pushing claws into the muck or sand where young crabs tend to hide. The juveniles fared better hiding among shallow-water grasses, but once they reached adulthood, or about 4.7 inches wide, the researchers found they could fend for themselves.
People might be a close second in their hankering for Maryland’s state crab. Watermen pulled an estimated 20 million crabs from the bay in 2024, valued at $41 million, according to the Maryland Department of Agriculture. That year’s population estimate published by the Chesapeake Bay Foundation totaled 238 million crabs, the second-lowest dredge count since surveys began in 1990. This comes three years after the all-time low of 226 million crabs counted in 2022.
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They tied young crabs to posts at different depths and times of year, checking on their welfare the next day. Since fish eat prey whole, they expected to find a fish on the line if they took the bait. Instead, almost all bait crabs were found as pieces of carapace or injured at the check-in time. Because crabs eat by crushing hard shells with their powerful pincers, partial bodies or injured crabs with missing limbs were attributed to crab predation.
“Cannibalism by large adult crabs accounted for greater than 97% of predation of juvenile crabs; predation by fish was not observed; and mortality from physiological stress was rare (less than 1%),” the paper states.
They published their work in the Proceedings of the National Academy of Sciences on March 16.
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