The United Boatmen of New Jersey weren't mincing words in the flier they sent out last month.

"The bluefish is now threatened with extinction," they wrote. "At this time purse seiners are trying to establish a market for bluefish in Japan.

"Should they succeed and then apply the same techniques they have used on the bluefish tuna, the bluefish will be eliminated as a recreational species."

Strong words convey strong feelings. The group, representing charter and party boat fishermen along the Jersey coast, was worried.

Officials from the Mid-Atlantic Fishery Management Council and the National Marine Fishery Service say they needn't be. Yet.

Stuart Wilk of the NMFS' Sandy Hook, N.J., office, said an attempt is being made to find a commercial market in Japan for bluefish, but so far it's small and exceedingly tentative.

One netter from Massachusetts plans to send a small batch of bluefish overseas this summer for Japanese processors to work on, to see if they can turn it into a profitable product.

Wilk said the fisherman, Frank Ziganowski of Fair Haven, Mass, described his plans in April at a meeting of a House fisheries and wildlife conservation subcommittee.

At the same meeting other fishermen and fisheries managers from the East and West Coasts also testified, and their message was that they saw no immediate market for blues anywhere, Wilk said.

Nonetheless, the news that there is any overseas commercial interest in blues at all has sport fishermen deeply concerned. Blues are practically pure sport, the backbone of the salt water recreational industry on the East Coast. A threat to them is a threat to the livelihood of thousands and the pleasure of hundreds of thousands.

In 1970 more than 125 million pounds of bluefish was caught on the East Coast, according to NMFS figures. Of that total only 6 1/2 million pounds were captured by commercial fishermen.

Over the last eight years the commercial catch has almost doubled, but the total is still only a tiny percentage of the sport catch.

Why aren't bluefish commercially viable? It has to do with the character of the flesh, which is oily and has a fairly strong fishy taste. The oiliness makes it undesirable as a freezer commodity; after freezing the meat becomes soft. The fishy taste keeps its market down in this country, where milder meat is favored.

But these constraints don't necessarily apply elsewhere. According to Wilk, the nutritional value of bluefish is as high as any fish.

"With the need for protein what it is in the world today, it's only a matter of time before someone says, 'Wait a minute, here's a millions of pounds of protein, let's exploit it,'" he said.

According to John Bryson, director of the Mid-Atlantic Fishery Management Council, that may already have happened. "The Japanese at one point indicated they would buy bluefish in large quantities from U.S. commercial netters," he said.

"It apparently won't be this year," he said, "but we don't know yet if long-range plans of this nature exist."

Should the Japanese, or any other nation, decide blues are worth importing, and should U.S. are worth importing, and should U.S. metters respond by going after the market the federal government could be caught short, with little power to regulate the take.

"The Secretary of Commerce cannot use emergency powers to regulate domestic fishermen," Bryson said. "We must have a fishery management plan in hand first before we can set limits."

His agency is working on just such a plan. "We're waiting for input from Woods Hole (marine science lab) on the status of stocks so we can determine maximum sustainable yield, optimum yield and so forth," he said.

The management plan will establish what kind of commercial pressure the bluefish population could stand without depleting stocks. With that information federal regulators could set rules for net mesh size, total allowable commercial catch, total sport catch, areas in which nets could be set and other conservation measures.

One thing is certain. If commercial fishermen start taking over a sizable chunk of the bluefish grounds, the sport fishermen are not going to like it.

"It will be a difficult situation," said Wilk. "It's never been done before. And let's face it, blues are the summer sport fishery in our area."