Imagine sitting in a small boat in quiet, open water on the Chesapeake Bay and peering down into the murky depths, when suddenly a massive SOMETHING breaks the surface right in front of you, not four feet away.

That's what Jack Cover reports happened to him this week as he was out on Eastern Bay, not far from Kent Island.  Cover, general curator for the National Aquarium, was looking for comb jellies to add to the aquarium's jellyfish exhibit. 

Cover reports in his blog that his gaze was diverted briefly by a cownose ray swimming on the surface in the distance, when without warning "a big object lauched out of the water like a polaris missile."  His initial shocked reaction was that a diver was surfacing, then he recognized this was a marine diver - a loggerhead turtle.

"It was the strangest experience,'' Cover told me.  He says he wasn't the only one startled, either.  The sea turtle, after gasping for air, took one look at him and dove back under water.  He watched it surface again four more times, each time farther away.

It's a rare treat to see a loggerhead this far up the bay.  Cover says they're seen more often in the lower bay, drawn in from the Atlantic in a quest for horseshoe crabs and blue crabs to feed upon.

But it may become rarer still to see the big sea turtles anywhere in the bay, or elsewhere along the Atlantic coast for that matter.  A group of biologists reviewing the status of loggerheads for the National Marine Fisheries Service has found that their populations off both the Atlantic and Pacific U.S. coasts are in danger of extinction.  The chief threat is from being unintentionally caught in fishing gear, primarily commercial longlines but also gillnets.  Their nesting beaches also are under pressure.   Dustin Cranor of Oceana, a Washington-based environmental group, reports that Florida officials say this year was one of the worst on record for sea turtle nesting there, in one of their prime areas for laying eggs.

Oceana and other conservation groups have petitioned the federal government to declare loggerhead populations on those two coasts endangered and to impose protective measures. For more, go here and here.

(2006 AP photo of a loggerhead at the South Carolina Aquarium in Charleston.  It was recovering after being found in poor shape on St. Simon Island in Georgia.)