THE custom-built, 50-foot Chesapeake Bay Foundation education boat cruised steadily up the Rappahannock River, passing forested shorelines in Caroline County on one side and King George on the other.

Middy Josephson, an elementary school teacher in Tappahannock, was one of 16 teachers taking part in "Teachers on the Bay," now in its 23rd year.

The Essex County teacher and others were on hand to learn about the Chesapeake Bay and its tributaries, so as to pass on scientific specifics and a feel for what's special about the waterways.

Cruising from an old steamboat dock at Wheatland farm in Essex County, she and the other teachers from the Northern Neck, Central Virginia and Maryland could only wonder what swam below.

A stop near Horse Head Point, not far from Port Royal, helped provide pictures--both digital and mental--the educators can share with students.

Those came courtesy of district fisheries biologist Bob Greenlee of the Virginia Department of Game and Inland Fisheries.

Greenlee and assistant Matt Blommell arrived in a small boat outfitted for electro-fishing, in which small electric charges are sent into the water to momentarily stun fish to the surface to be counted or examined.

On this day, the veteran fish biologist arrived early to net a sampling of fish they pulled out of a holding well to show the teachers.

From tiny to the size of quart buckets, they included pumpkin seed sunfish, gizzard shad, white and yellow perch, striped bass, wide-mouth bass, menhaden, spot, bluefish of white, blue and brown and a trio of eels difficult to scoop out.

But the real "wow" moment came when the pair moved off from the drifting education vessel to demonstrate what floats up when power is sent down poles extending into the water.

Greenlee--who does monitoring and fish management on the Chickahominy, James, Mattaponi, Pamunkey, and Rappahannock rivers--had prepared the teachers by explaining how the population of blue catfish has exploded on many of those rivers after being introduced in the 1970s.

He underscored how they'd thrived by having Blommell heft up a 40-pound blue cat half as big as he was.