PORT ISABEL — From the end of October to the end of April, Isabella Fishing Trips takes red snapper-seeking anglers into state-controlled waters because of a seasonal shutdown in waters under federal control.

Isabella’s boats travel 50 miles to Port Mansfield to find decent, legal fishing for their clients, many of whom will be gone when spring comes and the closure lifts.

Some recreational fishing-boat operators say they have modified their winter excursions in favor of kingfish or tuna, trying to wean anglers off red snapper.

It’s a tough time to be a red snapper enthusiast or business catering to them.

"It cuts at least 50 percent of our business, and literally our survival, to the bone because the Winter Texan population thrives on at least the opportunity to go catch a few snapper," said Leroy Summerlin, who manages Jim’s Pier on South Padre Island, describing the seasonal closure.

Proposed changes to federal fisheries law, intended to restore red snapper stock in the Gulf of Mexico, lay much of the blame for the fish’s decline on shrimpers and seek additional monitoring of commercial and recreational fishing vessels.

The proposed rules do not, however, seek to change the number of red snapper catches for anglers or the annual tonnage allocated to recreational fishermen.

A recent public hearing in Port Isabel regarding the proposed changes has rekindled a common complaint of South Texas shrimpers and fishermen.

They have been unfairly targeted and reports of the fish’s decline may apply in Florida but not in Texas, they say.

"Shrimpers are blamed for everything that is happening in the Gulf," said Carlton Reyes, a Brownsville shrimper and president of the Brownsville-Port Isabel Shrimp Producers Association.

Turtle excluding devices and other gadgets intended to allow certain marine life to escape trawlers’ nets have squeezed a slumping industry. "It’s a tremendous expense," Reyes said. He cites the $300-plus cost of turtle excluding devices and the number of shrimp that escape from federally mandated devices to protect red snapper.

Scientists say such measures are necessary to reestablish the stock. Fishermen say the fish are plentiful.

"We have a very healthy red snapper population," said Phillip Calo, owner of Osprey Fishing Trips on the Island.

"And Florida’s red snapper population has been depleted for years."

Summerlin said Texas’ red snapper population was "loaded up."

"I don’t see any way in the world we could endanger the population of the region, much less the entire Gulf coast," he said of recreational fishermen and headboat operators.

Scientists, however, stand by their assessment.

"The stock is in an overfished condition," said Steven Atran, a fisheries biologist with the Gulf Council.

Echoing the conclusion of a Gulf Coast Fishery Management Council report, he said shrimpers must reduce the number of red snapper caught in their nets — called bycatch — for the fish to rebound. Federal law requires red snapper stock to be replenished within 32 years.

Many red snapper die in shrimpers’ nets before being able to reproduce, he said.

In the 1980s, he said, "the stock was at an extremely low level, so we are coming back from a severely depleted stock."

With red snapper having lived as long as 53 years, replenishing the stock takes time.

"If we do nothing else to reduce shrimp trawler bycatch, there is no way we can get to that," Atran said of the legally mandated time frame.

Shrimpers’ nets look enticing to young red snapper, Atran said by phone from Tampa Bay, Fla.

However, rather than place additional restrictions on shrimpers, the Gulf Council believes the current depressed state of the shrimping industry will take pressure off red snapper.

For commercial and recreational fishing vessels, the proposed rules recommend developing an observation program in which observers will travel with randomly selected ships and keep track of fish caught, although the observers will not have enforcement duties.

Another proposal recommended including headboats in the monitoring.

Atran said the proposed changes would have little effect of fishermen.

"This does not really have any on-the-water regulation effects," he said.

Fishing-boat operators say that’s not the point.

They say that estimates are flawed because all of the Gulf goes into calculations.

"I feel like they’re used against us regardless of the information," said Calo, describing the possible data to be collected.

"If I show the fishing is slow, the federal government says the resource is depleted. If I show the fishing is terrific, they say we’re depleting the resource."