Hopewell, Va. ? Researcher Matt Balazik wears his passion for saving the Atlantic sturgeon on his right arm — a tattoo of the ancient fish — and lives it by counting the bottom-feeding giants in the James River.

The 30-year-old doctoral student is part sturgeon wrangler, part census taker as he patrols the river in a small boat, checking 1,000-foot-long nets for what scientists believe is the last viable reproductive population of Atlantic sturgeon in the Chesapeake Bay. Sturgeon, which have survived virtually unchanged since the time of the dinosaurs, are dwindling worldwide under the influence of human beings.

You hear these monster fish before you see them — Atlantic sturgeon leap out of the water and land with a loud splash, like a log dropped from above.

On a recent languid fall day on the river, in one of his last checks of the day in this shoestring recovery effort, Balazik has snared a sturgeon in his net and hauls it into the well of his boat.

Working with the skill of a Savile Row tailor, he records the big male’s length, girth and gender, tags it, then lifts it onto a scale before posing with his trophy for a picture and tossing the 6-foot-long, armor-plated fish back into the river’s silt-flecked waters.

“Their strength is just amazing,” said Balazik, who has learned how to work with them rather than against them. “They just have great personalities.”

Several species of sturgeon range from the Canadian Maritimes and the Great Lakes to Florida.

The once-bountiful Atlantic sturgeon that sustained North America’s first European settlers and Native Americans now may number in the hundreds in the Chesapeake Bay, but no one really knows.

“If sturgeon are to be restored to the Chesapeake Bay, it will happen on the backs of the James River population,” said Greg C. Garman, director for the Center for Environmental Studies at Virginia Commonwealth University and one of the leaders of this collaborative effort.