An annual survey of the Chesapeake Bay has found the blue crab population at its lowest level since scientists began tracking the beleaguered species more than 30 years ago.
The finding is expected to set off discussions about whether to tighten restrictions on crab harvests, such as what size crabs commercial watermen can legally collect, how many female crabs they can harvest and what hours they can spend crabbing. Crab season technically began April 1 but does not get going in earnest until waters are warm enough for the crustaceans’ liking — about 58 degrees, at least.
The continued struggles for the state’s signature shellfish come weeks after more promising news on the bay’s other popular seafood export, with Maryland’s largest harvest of wild oysters reported since 1987, but show the difficulties of managing species whose welfare depends not just on harvest pressures but on the whims of winds and weather.
That means fluctuations in the crab population are common, yet the trend line for various markers of the species’ abundance and health are pointing downward.
Blue crabs are estimated to number 229 million across both Maryland and Virginia waters, a third consecutive year-over-year decline, according to the survey, a cooperative effort of the Maryland Department of Natural Resources and the Virginia Institute of Marine Sciences.
That low number compares to an estimate of nearly 600 million as recently as 2019, and a record high of 852 million in 1993.
Scientists from both states have worked together to calculate the population estimates each winter since 1990, counting and measuring crabs hibernating in mud at 1,500 sites around the bay.
The number of spawning-age female crabs estimated to be in the bay based on this winter’s survey fell to 97 million, down from 158 million a year earlier, though still above a threshold of 72.5 million spawning-age female crabs considered necessary to produce a sustainable population for the years ahead.
The estimated juvenile crab population grew slightly to 101 million, up from 86 million the previous year. But that means a third-straight year of smaller-than-average young crab generations.
Maryland Department of Natural Resources officials said it’s impossible to pinpoint what caused the population decline.
Chesapeake blue crabs are spawned near the mouth of the bay, in Virginia waters, and as larvae rely on winds and currents to make it back into the bay, where they develop their shells and make their way up the bay in search of food and spawning grounds.
The state officials said they would be working with counterparts in Virginia and on the Potomac River Fisheries Commission “on a coordinated approach to set management measures for the 2022 crabbing season that address the conservation needs of the resource.”
Environmentalists called the survey results a troubling sign that crabs are suffering amid water pollution and related declines in underwater grasses, as well as increased predation from invasive catfish that have been multiplying in the bay in recent years. Development, use of fertilizers and inadequate wastewater treatment can all be linked to the health of blue crab habitat, and thus the abundance of the species itself.
“The results of this year’s survey continue a worrying trend for blue crabs in the Chesapeake Bay region,” said Chris Moore, the Chesapeake Bay Foundation’s senior regional ecosystem scientist, in a statement. “The continued low abundance of juveniles and adult males indicates the urgent need for action to protect these segments of the population.”
Acreage of underwater grasses has declined for two straight years, after a recent recovery in the bay’s aquatic vegetation, the bay foundation said. Grasses have suffered because of excess sediment and nutrients washing into the bay, clouding waters and blocking sunlight from reaching plant life.
That is bad news for crabs because juveniles use grasses to hide from predators, such as the blue catfish. The fish can grow to massive sizes, devouring fish and clams, which blue crabs also rely on for food, and feeding on young crabs, as well.
To give the crab population a boost, Moore suggested more should be done to protect adult female crabs from harvest so they can successfully spawn.
Maryland limits how many bushels of adult female crabs commercial watermen can harvest. In 2021, depending on the type of crabbing license they hold, watermen were limited to collecting at most 20 bushels of she-crabs a day in July and August and at most 39 bushels in September and October. (A bushel typically contains as few as 5 dozen large crabs to as many as 7 dozen small crabs.)
The state’s seafood industry, itself beleaguered and often at odds with environmental groups, could resist such changes.
Aubrey Vincent, sales manager at Lindy’s Seafood in Dorchester County, said she is eager for the state to explore further what may be hindering blue crabs from reproducing and growing.
“Something’s definitely having a negative impact,” she said. “It doesn’t look like it’s the commercial harvest, because that’s pretty steady.”
In fact, the blue crab harvest has declined in recent years, with the 41.6 million pounds harvested baywide in 2020 well below a 30-year average of about 61 million pounds, according to a panel of scientists known as the Chesapeake Bay Stock Assessment Committee.
Vincent said the seafood industry would work to help crabs recover, however that may be possible.
“We need to be respectful and make sure we’re not putting additional harvest pressure on,” she said. “We’ve adjusted what we’re doing, but it doesn’t seem to be getting us the results.”
Meanwhile, scarcity of crabs can often mean what’s become a pricey delicacy gets pricier. The cost of crab meat has skyrocketed in recent years given the limited supply of local shellfish as well as factors related to the pandemic, including labor shortages and supply chain issues.
To what extent that trend continues this year will become apparent soon: With temperatures forecast to surge into the 90s this weekend, watermen expect waters will warm enough to start to get this year’s crop of crabs stirring at last.