Blue crabs, as invasive species, have been causing a headache for the Italian government. However, on the other side of the Atlantic in the eastern coast of the United States, a recent annual winter dredge survey conducted in the Chesapeake Bay of Maryland has revealed a worrisome decline in the blue crab population.
According to the survey conducted jointly by the Virginia Institute of Marine Science and the Maryland Department of Natural Resources (DNR), the total population of blue crabs, also known as blue crabs, in the Chesapeake Bay is estimated to be 238 million, slightly higher than the record low of 226 million set in 2022, but still at the second-lowest level since the start of the winter dredge survey in 1990.
Last year, the estimated blue crab population in the same area was 317 million, only slightly below average. Now, the blue crab population has dropped by 25%.
The annual “crab population statistics” measure the number and health of the crab population, as well as the abundance in the bay, and this year’s report is one of the most severe in decades. The survey results can provide reference for the formulation of fishing regulations, such as catch limits and shortened fishing seasons, which also affect market prices and supply.
The dredge survey is conducted annually as a “snapshot,” where scientists and commercial fishermen dredge up blue crabs hibernating on the bay’s bottom during the cold winter for assessment, and then safely release them. The survey shows that all crab populations, from adult males (approximately 26 million) to females (1.08 billion) to juveniles (1.03 billion), are on a downward trend.
Mandy Bromilow, the blue crab program manager at the Maryland Department of Natural Resources, stated that the department is strictly enforcing current fishing regulations. “Our situation is alright,” Bromilow said. “Although the situation is not ideal, it’s not something we are particularly worried about.”
Part of the reason is that this year’s blue crab population did not fall below the critical threshold of 72.5 million spawning female crabs. The number of spawning female crabs this year is 1.08 billion, below the department’s target of 1.96 billion but not at rock bottom.
However, Allison Colden, Maryland Executive Director of the Chesapeake Bay Foundation (CBF), referred to the 2025 survey results as sending a “danger signal” for blue crabs. “The continuous five-year decline in crab numbers below average levels indicates that the changes in the bay environment are evidently disrupting the existing management of this important species,” she said.
There are many reasons contributing to the decline in crab numbers, from overfishing to habitat loss (such as the destruction of underwater grasses), predation—especially from invasive species like blue catfish—and runoff pollution. Experts are unsure of the reasons behind such significant annual fluctuations in the population of this species.
Scientists from the Department of Natural Resources noted that blue crabs are highly sensitive to factors like water temperature, and harsh winters may be to blame, as the cold currents are enough to kill the blue crabs spawning this season.
The Chesapeake Bay Foundation stated in a press release that the 2025 data is “worrisome” and urged Maryland to maintain the harvest limit for male crabs and enhance protection for female crabs, “including reducing the importation of ‘sponge crabs’ from Virginia.”
Bromilow mentioned that this population assessment will incorporate scientific literature, computer models, and years of winter dredge data, which could change the management approach of blue crabs in the bay, including male crab management.
While concerns are raised about the declining blue crab population on the East Coast, Italy is facing worries about the uncontrolled growth of blue crab numbers. Due to the lack of natural predators, blue crabs have proliferated in several places along the Italian coast, especially in the northern Po Delta, becoming an invasive species. Since blue crabs primarily feed on clams and mussels, aquaculture farmers in the Po Delta region have been significantly affected, as the industry is lucrative.
The Italian Ministry of Agriculture has been encouraging fishermen to catch blue crabs. However, since the local population does not have a tradition of consuming blue crabs, only a small portion of the crabs caught are used for consumption. Local fishermen also noted that the cost of catching and processing these blue crabs is too high.
According to online sources in Chinese, blue crabs, also known as blue crabs or delicious swimming crabs, are commonly found edible crabs on the Atlantic coast, known for their delicious taste. They typically inhabit mudflats, bays, and deltas.
Blue crabs are highly esteemed by the Chinese for their sweet, delicate flavor, and tender meat.