The Chesapeake Bay’s blue crab population has fallen to its second-lowest level since 1990, down 25% from last year, according to an annual study published Thursday. The numbers are alarming, environmental scientists say — but all hope is not lost.

There were an estimated 317 million blue crabs in the bay this time last year, according to the Chesapeake Bay Blue Crab Winter Dredge Survey, an annual project carried out jointly by the Maryland Department of Natural Resources, or DNR, and the Virginia Institute of Marine Science.

The study, based on dredging carried out at 1,500 sites across the Chesapeake between December and March, estimates that there are only 238 million of the crabs in the bay today, a collapse of 79 million, or nearly a quarter, over the past 12 months.

Perhaps worse, decreases were evident across all population segments. Juvenile crab abundance fell for the sixth year in a row, from about 138 million in 2024 to 103 million this year, a nearly 25% drop.

Meanwhile, spawning-age female crabs declined from 133 million to 108 million, a fall of 19%, and the adult male population dropped even more sharply, from 46 million to 26 million, a 43% decline.

The overall results mark the fifth straight year of substandard crab abundance. Only the 2022 total of 226 million was lower.

“The red flags are flying for blue crabs,” said Allison Coldren, Maryland executive director of the Chesapeake Bay Foundation. “With more than five years of below-average crab numbers, it is clear that changing conditions in the bay are undermining the current management of this important species.”

Mandy Bromilow, manager of the DNR’s blue crab program, also says the situation is concerning.

Bromilow says the findings show that the measures scientists have been taking in recent years — such as introducing bushel limits on adult male crabs in 2022 — have been insufficient in the face of the shifting and multifaceted world of Chesapeake Bay ecology.

Yet Bromilow points out that even though the current population of spawning-age females — a key indicator of the crustaceans’ reproductive health — is well shy of the 196 million figure local scientists consider ideal, it’s still higher than the threshold of 72.5 million, the level at which it’s understood that significant new measures are called for.

“It’s not a great situation to be in, but it’s not the worst-case scenario at this point. We’re still within the limits of our management framework,” she says.

The dynamics that shape blue crab abundance are so varied and complex it’s difficult even for those who study the matter to know which ones are having the strongest effect at a given time.

Blue crab populations are known for following boom or bust cycles in the best of times, and experts say factors ranging from climate change and oceanic conditions to predation and polluted runoff can have an impact.

A winter that featured several cold snaps probably didn’t help this year, Bromilow says. Nor did the ever-growing presence in the bay of blue catfish, an invasive species introduced locally in the 1960s and 1970s that “eats everything, including blue crabs.”

Another study could help provide answers. Scientists from the University of Maryland Center for Environmental Science, the National Oceanic and Atmospheric Administration and other research centers are currently carrying out a stock assessment of the blue crab population.

Rather than focusing on abundance, the assessment is designed to explore and evaluate the various environmental factors at play in the bay.

Its results will help environmentalists decide whether to use a different set of metrics for assessing blue crab health than the ones they’re employing now. Those were established in the wake of the most recent stock assessment in 2011.

Depending on the findings, it could mean anything from using a different set of population benchmarks to placing more emphasis on the importance of male blue crab numbers.

“The winter dredge survey provides a snapshot in time,” Colden said in a statement. “The upcoming comprehensive … assessment, due in 2026, will give us a more complete picture of the impacts of environmental threats to blue crabs, and what Maryland and Virginia can do to better protect them.

“Managers must heed those assessment results and act swiftly to protect the opportunity for the next generation to experience the joy of a summertime crab feast.”

The challenges faced by the blue crab are so many and complex that “only a comprehensive and collaborative approach will improve the population,” a statement issued by the Chesapeake Bay Foundation read.

To that end, the 58-year-old nonprofit is urging Maryland to maintain its current regulations for male crabs and further strengthen protections for female crabs, for Virginia to reduce its blue crab harvest, and for “the federal government to fully fund programs and agencies like the National Oceanic and Atmospheric Administration and Environmental Protection Agency that support regional clean-water initiatives that protect blue crab habitat,” according to the statement, which it issued Thursday.

In the meantime, some locals who deal in crabs are taking the survey in stride.

Crabs have been a staple on the menu of Costas Inn, the landmark seafood restaurant in Dundalk, since it opened in 1971. But co-owner Peter Triantafilos isn’t panicking.

Because the restaurant serves crabs year-round, he relies primarily on crustaceans from Texas, drawing on the Maryland blue population only when they’re in season.

“It shouldn’t impact our operation as much,” he said.

Have a news tip? Contact Jonathan M. Pitts at jonpitts@baltsun.com. Sun reporter Todd Karpovich contributed to this story.