Is the tide going out on sushi?

Owners of sushi bars in the United States are finding that increasingly expensive fish and a shortage of well-trained chefs from Japan are affecting the quality of their food. As a new type of sushi restaurant, which offers budget-priced raw fish meals, takes over the market once held by high-quality sushi restaurants, conscientious owners and chefs are concerned about possible health problems which can occur because of improper preparation.

``I wish I could just walk into the Fulton Market and buy fish for sushi at the low prices there,'' says Kakuji Miyachi, a New York sushi restaurant owner. ``But fish used for sushi have to be cut or prepared in special ways. You can't just use any fish.'' Most US-caught fish are not suitable for sushi, according to Mr. Miyachi. This is because maintaining the freshness of fish usable for sushi requires various techniques which American fishermen don't use. Most American fishermen aren't targeting the still-tiny US sushi market. Consequently, he and most owners import nearly 80 percent of their fish from Japan. Miyachi said tuna, flounder, and salmon are the only kinds he can rely on locally because other species lack consistency in quality and quantity.

Sushi has grown increasingly popular in the last five years, becoming a favorite cuisine among young professionals.

According to the Japan External Trade Research Organization, more than 300 of the 500 sushi restaurants in the United States have opened in the past five years. About 300 are in metropolitan New York.

About 500 sushi chefs poured into the US between 1981 and 1983, looking for better job opportunities than in Japan, according to Hajimu Tanaka, secretary of the Japanese Restaurant Owners' Association. ``The majority of them were experienced chefs,'' he says, meaning they had at least 15 years of experience. At that point, high-quality Japanese-style sushi became affordable to Americans.

The situation began to change in late 1985. While the dollar started what has turned out to be a steep descent against the yen, sushi bars continue to open. ``The rising yen is hurting the business very severely,'' says Miyachi. ``The yen soared by more than 40 percent in a year, but I can't easily raise the price because there are so many competitors around here.''

The rapidly rising yen caused two problems. Imported fish became expensive. And chefs were less inclined to come to America because salaries in this country were, in effect, dropping.

``Most competent chefs are over 30, and not many chefs who are established in Japan will be interested in leaving their comfortable life in Japan,'' says Senzo Ogasawara, a New York sushi chef. ``At 150 yen to the dollar, the salary they can expect in the US is not necessarily higher than what they can earn in Japan any more, and the life in a foreign country is not easy.''

Kingo Yamanashi, a New York-based tuna distributor to sushi restaurants, says experienced chefs are actually leaving the US for Japan. ``Several top-notch chefs have returned to Japan in the past few years, and I know some others who are talking about going back,'' he says.

Sushi bar owners have been forced to turn to young, inexperienced Japanese chefs to meet the growing demand. ``I estimate more than 80 percent of sushi chefs brought into the US in the past few years are not qualified to handle raw fish,'' says Mr. Tanaka. ``It takes at least 15 years of experience with a veteran chef until a chef becomes capable of determining the quality and freshness of fish by looking.''

Veteran sushi chefs hold that the quality of sushi is determined solely by the chef's competence. There is no way of preventing incompetent chefs from working at this point, Tanaka says. ``The only thing I can do is to urge customers to be alert and selective about the sushi restaurants they go to.''

The Food and Drug Administration is currently organizing guidelines on sushi preparation, expected to be completed in June.

``We are aware of the potential danger to public health of eating raw fish,'' says Joseph Puleo, senior food specialist for the FDA. ``But all we can do is to recommend the guideline to states and cities. The rest is up to them whether they enforce the guideline strictly or not.''

``There may have been several complaints in the past year, but as far as I know, there have been no cases of proven food poisoning of sushi,'' says Harvey Dlugatch, senior public health sanitarian of New York City, ``I don't think the situation is that serious yet.''