BOSTON – The catch for fishermen in the Northeast during the first three months following drastic rule changes fell 10 percent compared with last year but revenues rose 17 percent, according to federal statistics released this week.

The rules were enacted May 1 amid reports of broad confusion about the change and that numerous fishermen were keeping their boats docked due to the uncertainty.

It’s too soon to draw broad conclusions, but the relatively stable first-quarter numbers are cause for cautious optimism about the switch, said Patricia Kurkul, the National Marine Fisheries Service Northeast regional administrator.

“It’s sort of on track with what we saw last year, so there’s nothing catastrophic going on here,” Kurkul said.

But the early numbers are likely masking that a broad section of the fleet hasn’t started fishing yet because fishermen are limited to catching so few fish this year, said Jackie Odell of the Northeast Seafood Coalition, a fishing industry group.

“I know a lot of fishermen right now that are very, very concerned about their allocation for the whole year and don’t think there’s anything positive out of what’s taken place over the last three months,” Odell said Friday.

The catch got a boost because the new rules allowed fishermen into areas that had previously been closed in May, Odell said, and unusually high prices helped fishermen at the start of this fishing season.

The old system tried to stop overfishing by making fishermen less efficient through such methods as limiting their number of annual fishing days. In the new system, fishermen work in groups to manage an allotted catch of groundfish, such as haddock, cod and flounder.

The idea is to give fishermen added flexibility to try to plan their catch when prices are good and avoid struggling species.

But, in a key change, if fishermen catch their limit on one stock, they must stop fishing on all stocks. Environmentalists say the tough limits are needed to stop overfishing, but some fishermen say the limits on many species were set so low, they can’t make a living.

The new system’s early numbers, posted Thursday, indicated the total catch from Maine to New Jersey fell about 10 percent (8,590 metric tons to 7,702), compared with the first quarter last year.

But revenues rose 17 percent this year during the same period, increasing from about $18.3 million to $21.4 million.

Though the total catch was relatively even, fishing varied among ports. In Gloucester, the catch dropped about 13 percent in the first quarter, but New Bedford groundfishermen increased their catch by 10 percent.

Portland, Maine, saw a huge jump, with 61 percent more groundfish landings in the first quarter, compared to last year. But Kurkul said Portland may just be absorbing the catch from the state’s other ports, whose combined catch dropped 50 percent during the same period. The haul in Rhode Island was 15 percent higher than last year, but it dropped 43 percent in New Hampshire, an area where fisherman have been staying tied up, Kurkul said.

There were also major increases in the catch of robust species, such as Georges Bank haddock and redfish, which is a key goal of the new system.

“It shows that the fishermen know where to fish, when to fish, and how to fish, and what gear to use so they can target the healthy stocks and avoid the unhealthy ones,” Kurkul said.

Industry advocates say the statistics would tell a more complete story if they included the number of boats that went to sea during the quarter. Odell said the early catch may have been driven largely by fishermen who have bigger catch limits.

Brian Rothschild, a marine science professor at the University of Massachusetts at Dartmouth, said the benefits of the large haddock catch likely went mainly to big vessels, since they’re the only ones with the horsepower to tow the special nets that help fishermen dragging for haddock avoid other species.

Rothschild added that federal regulators have got to do better than stay relatively even with last year, when fishermen only caught a fraction of what they were permitted to catch.

“If this year we’re catching the same amount as last year, then the present system is no better,” he said.