Schools of eastern America's No. 1 marine sport fish, the bluefish, are piled up today off the coast of the Carolinas and farther south, where they will idle away the winter.

Come spring they'll assault favored fishing grounds up the coast all the way to northern New England, and happy saltwater sport anglers will marvel again at the abundance. Bluefish, bluefish everywhere -- a bottomless ocean of blues, a horn of plenty without end.

Or is it?

"There have been times when there were no bluefish," Stuart Wilk said ominously last week. "And that could happen again."

Wilk is the National Marine Fisheries Service bluefish expert. He was in town to put on a brief presentation on the life and times of the fish called "chopper."

He tossed out figures backing up what everyone who fishes knows, which is that thunderous hordes of blues constitute by far the biggest marine sport fishery in the East. In 1979, for example, East Coast recreational fishermen caught 96 1/2 million pounds of blues. Next on the list was summer flounder, at 23.8 million pounds.

So with all these blues, what could go wrong?

Wilk said we may be on the verge of taking too many. The overall 1979 bluefish take, including commercial catches and a small tally from the Gulf of Mexico, was about 114 million pounds. The NMFS figure for "maximum sustainable yield" of bluefish is somewhere around 110 million pounds a year.

Wilk cautioned that the sustainable yield figure is tentative -- an estimate -- but assuming it's moderately accurate, the current catch is already hovering around and even over maximum sustainable yield.

And the commercial catch is on the rise. The fear fish managers have is that sudden soaring demand could decimate bluefish stocks.

With technological advances, commercial fishing for blues is getting more effective. Total commercial landings in the 1960s averaged about 5 million pounds per year; in the 1970s, 10 million. In 1979 the tally was over 13 million pounds and 1980 estimates set the take at 14.5 million pounds.

Both Wilk and John Mason from the Mid-Atlantic Fishery Management Council expressed concern that eventually a major commercial market for blues will open up, probably outside the United States, and U.S. commercial fishermen will respond by scooping up all the blues they can get their hands on to fill the demand.

"It's the American way, isn't it?" asked Wilk.

Fishing for recreation also is the American way, and a threat to bluefish supplies is a plain and simple threat to East Coast recreational fishing. In 1979, recreational fishermen spent $41.4 million in pursuit of bluefish, according to government figures. The commercial catch the same year brought $2.1 million at the dock.

With those figures as a backdrop, the Mid-Atlantic Fishery Management Council staged seven heavily attended public hearings up and down the coast to assess the need for a bluefish management plan. Last month they came up with a draft plan calling for no restrictions on the booming recreational fishery, but a limit on the commercial catch of 15 percent of the previous year's sport catch or 15 million pounds, whichever is greater.

The draft management plan is designed to keep the bluefish catch at current levels, both for sport and commercial fishermen. The Mid-Atlantic Council submitted the plan to NMFS with this justification: "The commercial sector is at a point where it is likely to expand . . . This expansion, if uncontrolled, could lead to severe reductions in the abundance of bluefish. Such reductions would impact on the recreational fishery and make it difficult to meet the objectives of the plan (to sustain current catch levels)."

NMFS is studying the draft management plan, but according to Mason, the federal agency has indicated an unwillingness to implement it. "The U.S. doesn't feel a management plan is necessary to maintain the status quo," he said, adding that federal officials want a problem to exist before they take steps to alleviate it.

I asked Wilk this: "If the annual bluefish take is already at or above maximum sustainable yield and nothing is done to control its growth, aren't we playing with fire?"

He said, "You must understand that our figures are tentative estimates, but if they are correct, yes, we are playing with fire."