GALVESTON, TEX. -- A wave of dead sea turtles washing up on Texas beaches has touched off a high seas campaign by law enforcement authorities to clamp down on shrimpers whose nets are not equipped with the trapdoor-like turtle excluder devices required by federal law.

"There has been no proof that the turtles were actually killed by the shrimpers. But they were not poisoned and they were not shot, and the morning that shrimping season began, there was a massive turtle kill," Coast Guard spokesman John Barber said.

The bodies of 31 turtles, including 17 endangered Kemp's ridley turtles, have been found on Texas beaches since the state's estimated 1,000 shrimpers began their summer Gulf of Mexico harvest July 8, officials said.

Coast Guard crews have issued 21 citations to captains of shrimp boats found not to have the controversial excluder devices, said Coast Guard spokesman Gene Maestas. The captains face up to six months in jail and $25,000 in fines for violations.

The turtle excluder devices enable turtles caught in shrimpers' nets to escape through a trapdoor mechanism as the shrimp boat plows through the water. Without them, the air-breathing turtles drown as they are dragged along. Shrimpers contend that the turtle excluder devices reduce their catch by as much as 30 percent because they allow shrimp to escape along with turtles.