Sur­vey shows spike in young crabs, but over­all count down

DNR says win­ter num­bers in­di­cate slow start, but bet­ter sea­son could still fol­low

The Enterprise - - Front Page - By DANDAN ZOU dzou@somd­news.com

A newly re­leased win­ter sur­vey showed an in­crease of ju­ve­nile crabs this year in the Ch­e­sa­peake and its trib­u­taries. But the num­bers of adult male and fe­male crabs both dropped, bring­ing the over­all bay­wide crab pop­u­la­tion down by tens of mil­lions when com­pared to last year.

The de­cline in adult crabs could mean a slow start to this har­vest sea­son that started in April, but water­men said things could im­prove as young crabs grow into mar­ket size in mid-sum­mer.

“They sort of tell us it’s gonna be late in the year be­fore we have a larger num­ber of adult crabs,” said Tommy Zinn, pres­i­dent of the Calvert County Water­men’s As­so­ci­a­tion. “Hav­ing an in­crease in ju­ve­nile is a good sign, mean­ing the fu­ture looks bet­ter down the road though we will have a slow pe­riod in be­tween.”

Con­sid­er­ing the un­usual cold spell from Fe­bru­ary through April, Zinn said in a phone in­ter­view Wed­nes­day he’s not sur­prised by the re­sults.

“We were not ex­pect­ing good num­bers from the sur­vey, not on the adult crabs,” he said. “A lot of them died be­cause when they came out of their hi­ber­na­tion state, [be­cause] it got su­per cold. It shocked them and killed them.”

Ac­cord­ing to the Mary­land Depart­ment of Nat­u­ral Re­sources, this year’s cold weather and ice cover took a toll on the adult crab pop­u­la­tion, caus­ing an es­ti­mated 35 per­cent mor­tal­ity of adult fe­males win­ter­ing in state wa­ters.

Willy Dean, pres­i­dent of the St. Mary’s County Water­men’s As­so­ci­a­tion, agreed that the cold win­ter had some neg­a­tive ef­fect on the adult crabs, though he said it’s hard to say how much.

“It’s gonna be a very, very tough sea­son,” Dean said Wed­nes­day over the phone. “We just need to ride this one out.”

In ad­di­tion to the bad weather, Dean thinks the grow­ing num­bers of rock­fish and blue cat­fish also have some­thing to do with fewer adult crabs in the bay.

“A lot of it is pre­da­tion,” he said, not­ing he has seen more rock­fish him­self and has heard that there’s an in­creas­ing amount of blue cat­fish, es­pe­cially far­ther up in the Po­tomac River.

Zinn said he’s heard the same thing about the blue cat­fish. As crabs shed their shells to grow, that process makes them highly vul­ner­a­ble to preda­tors like cat­fish dur­ing those pe­ri­ods.

“Like crabs, cat­fish are bot­tom feed­ers, too,” he said. “If there’s an abun­dance of cat­fish, they can take a toll on the num­ber of crabs.”

Bi­ol­o­gists use dredge equip­ment each win­ter to cap­ture, mea­sure, record and re­lease blue crabs at 1,500 sites. Ac­cord­ing to the an­nual sur­vey con­ducted by Mary­land DNR and Vir­ginia institute of Ma­rine Sci­ence from De­cem­ber through March, bay­wide crab pop­u­la­tion is es­ti­mated to be 371 mil­lion, a 20 per­cent drop from last year’s 455 mil­lion, driven largely by the smaller num­bers of adult crabs.

In 2018, DNR said the spawn­ing fe­male stock de­creased more than 40 per­cent from a record high of 254 mil­lion to 147 mil­lion, drop­ping below the tar­get level of 215 mil­lion, but re­main­ing above safe lev­els.

Adult male crab abun­dance de­clined 23 per­cent from 76 mil­lion to 59 mil­lion. The ju­ve­nile crab pop­u­la­tion in­creased 34 per­cent over last year, reach­ing 167 mil­lion.

“Even with the er­ratic weather, which in­cluded snow in April, the blue crab pop­u­la­tion re­mains well within parame- ters, show­ing that the state and our part­ners are man­ag­ing the species well,” DNR Sec­re­tary Mark Bel­ton said in a re­lease Wed­nes­day.

The 2017 bay­wide crab har­vest level also de­creased, drop­ping from 60 mil­lion to 54 mil­lion pounds, ac­cord­ing to DNR.

“This year’s re­sults give us op­ti­mism that our man­age­ment ap­proach is ef­fec­tive at con­serv­ing ad­e­quate num­bers of crabs even when the num­ber of ju­ve­niles is low and win­ter mor­tal­ity is high,” DNR’s Fish­ing and Boat­ing Ser­vices Di­rec­tor David Blazer said in the same re­lease.

But at the end of the day, Zinn said the re­sults should be viewed with a grain of Old Bay. “You can’t put too much faith into what the sur­vey shows,” he said.

One year, for ex­am­ple, the sur­vey pre­dicted a bad year but water­men ended up hav­ing an above-av­er­age sea­son, he said. Another time, the sur­vey in­di­cated a good year, but water­men strug­gled to find enough crabs.

Con­sid­er­ing that many vari­ables could af­fect the har­vest, “what [the sur­vey­ors] see in Jan­uary and Fe­bru­ary doesn’t mean that’s what it’s gonna be like in May or June,” he said. “It’s Mother Na­ture.”

STAFF PHOTO BY DANDAN ZOU

Tommy Zinn throws back an un­der­sized crab off his boat when trot lin­ing in the early morn­ing last Au­gust on the Patux­ent River near Hellen Creek.

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