Blue crab population in Chesapeake Bay hits record high

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The number of blue crabs in the Chesapeake Bay has hit an all-time high, marking the lowest number in more than three decades of crustacean tracking, experts said.

The directory Baywide Blue Crab Winter Dredging Surveywhich results in an estimate of the blue crab population this year counted 227 million crabs, the “lowest abundance observed since the survey began in 1990,” the count authors said. Officials say the survey conducted by the Maryland Department of Natural Resources (DNR) and the Virginia Institute of Marine Science (VIMS) is key to knowing how to manage the number of blue crabs that can be harvested each year by commercial and recreational fishing operations.

“He provides the guardrails for how we handle the crab harvest,” said Michael Luisi, acting manager of Maryland DNR Fishing and Boating Services, whose division is helping with the investigation.

This year’s survey raised several concerns: The number of juvenile crabs has dropped to around 101 million, marking the “third consecutive year of [a] number below average; and the number of female crabs of spawning age has fallen from 158 million crabs in 2021 to 97 million. According to the survey, there were also 28 million adult male crabs, which experts called “the lowest abundance of adult males on record”.

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Experts said the number of female crabs that could spawn in the coming year is an important “indicator of future spawning potential”. By knowing the total number of crabs in the bay, they said, they can determine how many are caught each year. Even with lower numbers, Maryland DNR officials said the number of spawning-age females is “at a level capable of producing a strong year-class.”

Virginia Marine Resources Commission officials, who helped with the investigation, said in a statement that adult female crabs are “the key to conservation.” Each female can lay an average of 3 million eggs per clutch and in a year she can average up to three clutches. Female crabs seen in the survey are expected to spawn from late May to mid-summer, which will contribute to next year’s juvenile population, officials said.

While water quality and vegetation in the bay have improved, marine experts in Virginia said they are concerned that “blue crabs are still vulnerable to low oxygen levels from nutrient runoff and lack of seagrass, which can leave juveniles vulnerable and soft crabs without [habitat] to take refuge.

Experts say there are likely several reasons for the decline in the blue crab population, including the changing state of the ocean and rising water temperatures, as well as the impacts of storms and currents on habitats. crabs and an increase in crab predators such as blue and red drum catfish.

“Climate change could absolutely be one of them,” Luisi said, noting that for juvenile crabs, climate change could impact the timing of their food resource availability, thereby affecting their growth.

“Air, tides, winds, warmer water or how they will find protection in the bay all impact the crab population,” Luisi said.

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Although experts said they believe they have maintained “safe levels” in managing the number of blue crabs harvested each year, “the abundance of adult blue crabs has steadily declined”.

While many wildlife watchers worry about whether the bay’s blue crabs are overfished, Luisi said they don’t think that’s the case. In 2021, the maximum percentage of females that could be harvested each year without overfishing was 26%; which compares to a peak percentage of 37 percent a decade earlier, according to the survey and summaries.

About 41.6 million pounds of blue crabs were harvested from the bay and its tributaries, according to a 2021 report report of the Chesapeake Bay Stock Assessment Committee.

The dredging investigation has raised concern from environmental groups worried about the bay and its wildlife.

“Crabs have a fairly short lifespan of two to three years, so if you have two to three years of low production, that sets a trend that could continue into the future unless something changes,” said Allison Colden, Maryland Fisheries Officer. Chesapeake Bay Foundation scientist.

“Environmental factors are so unpredictable,” she said. “But we’re hoping they’ll take this further. … Otherwise, we’re bracing for a downtrend if it continues.

The annual dredge survey is conducted in winter when blue crabs are less active. Biologists use equipment to dredge them at 1,500 sites along the Lower, Middle and Upper Bay of Maryland and Virginia. The measurements, weight and sex of the crabs are recorded, then they are released.

Experts said they were developing a plan to try to figure out how to improve the crab population and maintain the “health and sustainability” of the species, given the declines they have seen.

“It’s a very resilient population, and they’ve been around longer than us,” Luisi said. “They’ll find a way, and we’ll deal with the consequences to make sure we allow enough of them to stay in the bay to increase production.”

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