Big Problems with Blue Crabs
Our blue crabs are in trouble again. Since last year, the juvenile crab count had plummeted to 111 million, down from 587 million in 2012, according to the 2013 Winter Dredge Survey results. The overall number of crabs in the Bay dropped by over 60 percent.
Blue crabs may, once again, be approaching the crisis levels of five or six years ago.
The trophy season opened Saturday with half-gale winds and whitecaps from shore to shore. Despite that, the Bay was full of fishing boats, a few of which shouldn’t have been out there.
Wild Turkey Spring Season: thru May 23
In a wide-ranging press release, Maryland Department of Natural Resources emphasized the good news of a 52 percent increase in this year’s female spawning-age population. That growth is laudable.
But the total 2013 population estimate of 150 million spawning females remains well below the target of 215 million, the level for optimum species viability.
We must also take into account the precipitous and unexplained drop of spawning-aged sooks in the 2012 Winter Dredge. That survey revealed that somehow about half of our entire estimated population of spawning-age females has vanished.
DNR characterized the 2012 event as an “anomaly” and permitted previously approved commercial harvests to continue on the remaining spawning stock, pushing it down even further. This year’s disappointing population of juvenile crabs, the lowest number in more than 20 years, should come as no surprise.
Five or so years ago, the Chesapeake’s blue crab situation was declared a disaster at the federal level. Maryland, Virginia and the Potomac River Fisheries Commission were forced to cooperate for recovery.
At about that same time DNR was discovering faults in its science of blue crab reproduction.
Policy up to then allowed mature (once-spawned) female crabs to be harvested without regard to limits or size. Maryland fisheries scientists claimed that blue crabs reproduce only once in their lifetimes, so their post-spawn harvest would have no significant effect on reproduction.
Subsequent studies reversed that finding, discovering that many females spawned successfully multiple times. Strict emergency limits were adopted in both Virginia and Maryland to protect the female spawners.
The short-term effect was mind-boggling. Within three years, the population exploded from 255 million to 674 million. DNR hesitated to attribute the miracle to the presence of a larger population of spawning-age female crabs. However, the immediate and unprecedented population growth was unmistakable.
Confidence pushed the pendulum too far. DNR allowed watermen to resume taking breeding-age sooks in greater numbers.
Trouble was not long in coming. The spawning-age female blue crab population began another nosedive following the 2010 season, which coincidently saw record commercial harvests.
Despite DNR assurances that theoretically safe target levels of harvest have never been exceeded, the overall Chesapeake Bay crab population decreased throughout 2011 and 2012. The Winter Dredge Survey for 2013 confirmed that the blue crab was again in trouble and emergency restrictions necessary.
Does this sound like a pattern?
Catch limits are inevitably optimistic. Commercial pressure for maximum harvests is relentless. Eventually something goes wrong. The end result is unavoidable: population exhaustion.
For the blue crab to flourish in the Chesapeake, we need a different theory of management. A philosophy that puts the viability of the species first and demands of the marketplace second might have a chance at success.