Could chilly Chesapeake spell slow crab season?

Crabbing season officially begins in Maryland today, but the Chesapeake Bay's blue crabs apparently haven't gotten the word.

My colleague Richard Gorelick reports that watermen, seafood dealers, restaurateurs and state natural resource officials all believe that chilly bay water temperatures lately could mean a meager harvest for now.


"The cold temperatures are likely to keep early catches low," Brenda Davis, blue crab program manager of the Maryland Department of Natural Resources, told Richard. "Until the water warms up, crabs are not very catchable."

Bay scientists have a slightly different take on it.  The Chesapeake's waters have been a bit chillier than normal in recent days, which could make crabs that much slower to stir from their winter slumber.


But bay water temperatures have been about normal overall, they say. It's too soon to predict, they add, if cool spring weather will impact harvest later in the year, when most Marylanders are looking for their favorite seafood.

And besides, crabs normally don't show themselves in this part of the bay until later in the spring anyway.

So how cold has the bay been?  Well, as of last Thursday, the average water temperature off Annapolis was 42.9 degrees Fahrenheit.  That's the coldest measured there since 1986, according to oceanographer Doug Wilson of the National Oceanic and Atmospheric Administration.

"For the record, the average 28 March temperature since 1986 has been 46.2 F," Wilson said in an email.  It seems especially cold now since last year on that date, the water was a balmy 51.4 degrees Fahrenheit, thanks to a nearly nonexistent winter.

March normally sees a pretty rapid rise in bay water temperatures, Wilson points out.  In 1993, he wrote, it went from 33 degrees F on March 15 to above 43 degrees by March 28.

Still, as chilly as it's seemed in recent days, it hasn't been all that abnormal, except in comparison to last year.  The average water temperature for last month was 41.5 degrees, Wilson reports, only about a degree below the 1986-2013 average.

Donald F. Boesch, president of the University of Maryland Center for Environmental Science, also points out that overall, bay surface water temperatures so far this year have been warmer than average, and even slightly above for the month of March.  Check out the mid-bay data from DNR's Eyes on the Bay web site.

What's notable, Boesch adds, is that water temperatures have not been warming as much as they would usually during the past two weeks because of colder than normal weather.


"This could delay the normal activity of blue crabs for this time of the year," he acknowledges. But that "doesn't mean they won't become abundant when it warms," he adds.

A better indicator of abundance will come in a few weeks, when Maryland and Virginia release their annual survey of the bay's crab population. Since 1990, it's been conducted during the winter when the critters are dormant, having burrowed into the muddy bottom to await warmer temperatures. Last year's tally was 764 million, the highest number since 1993.

A big survey result like that doesn't automatically translate into a bumper crop at local crab houses and seafood markets, though.  Two-thirds of the crabs counted in the winter of 2011-2012 were juveniles, too small to be harvested until mid- to late summer.  Weather also plays a key role in the harvest, as storms can drive crabbers off the water - and the crabs into hiding for days afterward.