Blue crab survey results are good
Last week, Maryland’s Department of Natural Resources released the results of the 2016 Blue Crab Winter Dredge Survey and the results are good for the second year in a row.
The overall crab population has increased for two years consecutively, including the number of spawning-age females. However, the number of females still remains below the target managers from Maryland, Virginia and the Potomac River Fisheries Commission are aiming for.
Every December to March, teams of scientists from Virginia and Maryland conduct the survey at 1,500 different sites in the Chesapeake Bay and its tributaries. The crabs are dredged from the frigid bottom of the Chesapeake Bay, where they lie motionless during the cold winter months. Workers dredge the bottom in specified locations and the material is brought up to the surface. They simply count the number of crabs, which creates an accurate snapshot of the crab population throughout the entire Chesapeake Bay from year to year.
The winter dredge survey has been taken annually since 1990. Just looking at all the dips, blips and troughs on the line graph depicting the total number of crabs estimated in the Chesapeake Bay the last 27 years is enough to give a person a serious case of vertigo. The increase in population the last two years could be the start of a trend, but it’s too early to break out the champagne (or crab knockers) yet.
Blue crabs have a complex life cycle. They are born in the bay and its tributaries as microscopic larvae that look more like waterborne aliens than the hard-shelled crustaceans that end up on our picnic tables each summer.
They float out to the ocean on wind and currents and return several months later in much the same fashion to settle in the grass beds of the bay. They are tiny — not even a quarter of an inch from point to point in size — and they need those grasses for protection.
These tiny crabs are tasty morsels for a whole host of predatory creatures from sea turtles to herons, croaker to catfish. Even adult crabs are known for their cannibalistic predilection for dining on juveniles. It’s a perilous life for a growing crab.
Odds are literally one in a million that a crab survives to adulthood (defined as over 2.4 inches by DNR for this study). A female can spawn several times as an adult, but each time just a measly three eggs have a shot at survival. This fact alone should make everyone want to protect as many adult female crabs as we can.
We’ve implemented new rules already in the past few years to protect females. Today, recreational crabbers can’t take any female crabs at all. The total number of crabs recreationally harvested is difficult to estimate and not insignificant, but the majority of crabs harvested each year aren’t taken by recreational fishermen. Restrictions need to stay in place, or better yet get tougher for the whole crab population is still below ideal numbers.
Just two years ago, the female population was below the minimum threshold of 70 million, indicating the fisher y was in grave danger.
Thank goodness the numbers went up last year, to 101 million. And this year, the numbers are even higher, 194 million. But 194 million is still 21 million crabs short of the goal of 215 million female crabs recommended by scientists to sustain a strong fishery.
Mother Nature is capable of throwing us some serious curveballs that can challenge even the soundest fishery practices. Natural fluctuations in population are expected. An overabundance of predatory red drum in 2013 and a bad winter kill in