This Week on Chesapeake Summer...Survey Team Monitors Horseshoe Crab Levels SINEPUXENT BAY, MD (wypr) - Ten years ago, the population of horseshoe crabs was declining, prompting tighter restrictions on harvesting them and setting off annual surveys to check on their status. In this edition of Chesapeake Summer, WYPR's Joel McCord joins a survey team in the Coastal Bays.

For marine biologists Carol Cain and Steve Doctor, it's been a frustrating month. They have been hauling a boatload of gear to islands in Sinepuxent Bay during the evening high tides at the full moon and new moon to survey swarms of mating horseshoe crabs. But the crabs haven't shown up.

This year we've had storms and it seems that if the wave energy isn't just right, or perhaps the barometric pressure that's a guess the conditions aren't just right they're not going to come up and spawn. So we're hopeful tonight that we'll see some.

This is the next to last night this season they'll patrol these beaches in sight of the boardwalk rides of Ocean City.

Doctor, who works for the state department of natural resources, runs the boat onto a beach at the northern end of Assateague island and throws an anchor into the sand.

They scramble ashore and begin the hunt but find only the tracks of ghost crabs, tiny white creatures that skitter along the sand. Does this mean conditions still aren't right?

Well, let's go see what's going on at another beach. I wouldn't take one beach for all of it. We got a couple hours yet.

A few meters down the beach, Cain, who works for the Coastal Bays Program, spots a female burrowing into the sand with one male clasped onto her shell from behind and another pushing in from the side.

The first male that can get onto the back of her shell will latch on And then the others are called satellite males. And they just try to crowd in and get a piece of the action, so to speak.

The female deposits as many as 4,000 eggs at a clip in the sand and the males fertilize them. As she drags them along behind her, the sand covers the eggs until they hatch at the next lunar cycle and tiny horseshoe crabs swim away.

She's 227, I mean he's 227.

Doctor grabs the first crab and begins measuring in millimeters as Cain records the information.

But after finding only those three, they climb back in the boat and head for Skimmer Island, a huge shifting sandbar north of the Route 50 Bridge where masses of birds have taken up residence.

Horseshoe crab eggs help fuel migrating shorebirds; the crabs are used for bait in conch and eel fisheries and their blood is used for testing medicines. That's why worried fisheries regulators moved to cut harvests when they saw the decline in 1998.

Now, DNR scientists say they are seeing increases.

But Cain and Doctor see only empty helmet-shaped shells when they step onto Skimmer Island, raising a ruckus among the egrets, sea gulls and glassy ibises.

There's an awful lot of dead on this beach. Something happened, you know. They spawned in here at some point. See if we can find the eggs.

Soon, they see two lone males, a female with three males and more. And then, the mother load; a mass of crabs so large it is impossible to count them, their shells scraping together as they climb over each other. But it's just beyond the beach where Cain and Doctor are doing their survey.

Humph. It's just amazing.

This beach had none last year. Now we're sampling that beach and they all move over here. How frustrating is that?

The biologists marvel for a few minutes, then head for home wondering whether they should change their sampling site next year.

I'm Joel McCord, reporting on Sinepuxent Bay for 88.1, WYPR.
© Copyright 2009, wypr