GALVESTON, Texas (AP) _ Five shrimpers were arrested off the Texas coast in a federal crackdown on fishermen working without net equipment to protect sea turtles.

Two shrimp boat captains arrested Thursday off Freeport and Galveston were headed for the Harris County Jail in Houston. Three others arrested off Port O'Connor were held without bail in the Nueces County Jail in Corpus Christi pending court hearings.

All are accused of violating federal laws that require them to use turtle excluder devices, or TEDs, to protect turtles that can get caught in shrimp nets and drown. The penalty for criminal TED violations can be up to six months in federal prison and $25,000 per incident.

The arrests bring to six the number of captains accused of TED violations after their shrimp boats were boarded in Texas waters.

Authorities announced earlier this week they were beefing up enforcement along the Texas coast after more than 31 sea turtles, including 17 endangered Kemp's ridley turtles, were found dead.

The cause of the turtles' deaths has not yet been determined, but environmentalists have blamed the shrimpers.