Even as Cubans continue to stream toward South Florida on boats at an accelerating pace, the illegal traffic in Haitians has apparently dried up -- and no one is sure why.

Since October, the beginning of its fiscal year, the U.S. Border Patrol has detained 1,259 Cubans who landed on U.S. soil, more than twice the number for all of fiscal 1998. The Cubans are also keeping the Coast Guard busy: Its vessels have interdicted 488 at sea, 158 in May alone.

But those numbers are in stark contrast to the Haitian statistics.

After catching 147 Haitians on land in the first three months of 1999, the Border Patrol has apprehended none in April and May. And while some may be getting into South Florida undetected, the Coast Guard's numbers suggest not many are trying.

The Coast Guard, which intercepted 300 Haitians through April, including 206 in February, has picked up none in May.

The authorities are not alone in noticing the surprising trend.

Florvil Samedi, administrator of the Haitian Refugee Center in Miami, said the past two months have been unusually slow at the group's office, and word of new arrivals scarce.

``I wouldn't say it has completely dried up, but I don't hear anything about them coming by boat,'' Samedi said.

Cause of decrease unclear

Because of the shadowy nature of alien smuggling, authorities say they can only speculate over what is behind the decrease.

Samedi and the authorities say the drop seemed to follow the March drowning of as many as 40 Haitians off the Florida coast, an event that prompted international headlines.

The calamity may have discouraged some from trying, said Dan Geoghegan, assistant chief for the Border Patrol's Florida sector. Despite some doubts cast on the extent of the disaster, he said, investigators now believe the initial reports that two overloaded smuggling vessels sank.

``You figure that the Haitians are understanding it's dangerous,'' Geoghegan said.

Samedi said he has been speaking frequently on a Port-au-Prince radio program, encouraging Haitians to stay home and ignore smugglers' recruiters who claim it is easy to obtain jobs and legal status in the United States.

Still, those factors alone seem unlikely to reduce traffic so drastically, especially at a time when Haiti is once again mired in political and economic crisis.

Geoghegan said authorities in the Bahamas, from which most of the boats that carry Haitians to Florida depart, may be cracking down.

But the Bahamians say they are doing nothing different and are equally flummoxed. They say they have noticed the same trend as U.S. authorities: fewer Haitians and more Cubans using their territory as a springboard to Florida.

``I don't know that we have been taking so many new measures,'' said Harcourt Turnquest, permanent secretary of the Bahamian Ministry of Security. ``We have been doing the same things we have always been doing.

``But the Haitians have not been coming up from south of us in the numbers they had been. I don't really know what the reasons are. It may be that something has happened in Haiti.''

Some figures suggest the Haitian traffic may have been slowing for some time. The pace of interdictions of Haitians by the Coast Guard this year lags well behind that of last year, when the total came to 1,926.

Smugglers prosecuted

If anything has slowed the traffic between the Bahamas and Florida, Turnquest said, it's the dramatically stepped-up prosecutions of smugglers by federal authorities.

``I think that would have some impact on the Bahamians who are in it for purely financial reasons,'' Turnquest said. ``Definitely.''

Yet the string of arrests and convictions of smugglers seems to have had little effect on the Cuban traffic, which investigators say is now driven primarily by professional rings equipped with fast boats.

Those numbers, while nowhere near the massive exodus during the 1994 Cuban rafter crisis, are large enough to raise concerns among authorities.

``It's not an alarming trend,'' said the Border Patrol's Geoghegan. ``It's not an exponential increase. But it's still a sustained increase for the past 13 to 14 months.''

The busiest month so far was April, when 409 Cubans were apprehended at sea or on land. Authorities are confident their figures reflect almost all the arriving Cubans, most of whom turn themselves in because they are virtually assured of lenient treatment under the Cuban Adjustment Act.

The smuggled Cubans are typically dropped off at night in small groups, usually on beaches in the Florida Keys, but sometimes as far north as Sunny Isles Beach. Others land on Miami Beach and Virginia Key.

Authorities expect an upswing. Because of calmer seas, traffic from Cuba usually spikes in May, June and July, Geoghegan said.