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Chesapeake blue crab abundance falls to lowest level since scientists began tracking the population in 1990

Scott Dance, The Baltimore Sun on

Published in Science & Technology News

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.

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