Game wardens have discovered as many as 3,000 dead adult and juvenile sharks tangled in a long stretch of illegal fishing netting off the Texas coast, the state's Parks and Wildlife Department said.
Department spokesman Steve Lightfoot said the wardens found the net off Texas' southern South Padre Island near the border with Mexico.
"About 3 miles of gill net was removed just past the third sandbar near the mouth of the Rio Grande," the department said in a statement. "The nets were running north to south, catching anything that attempted to get into shallow water."
No arrests have been made, Lightfoot said, according to The Associated Press.
"This is by far the most sharks I have ever gotten in one load," Texas Parks and Wildlife Sgt. James Dunks told local KGBT-TV after making the discovery on Sept. 7.
"We have here probably two to three miles of gill net that was placed in our waters about four miles north of the Mexico border right off the beach," Dunks said. "Unbelievable amount of sharks, anywhere between two and three thousand black tips, bonnet heads and sharp nose shark."
Authorities suspect Mexican fishermen set the illegal nets.
According to KGBT-TV, overfishing has destroyed the populations of fish on the Mexican side of the border, and Mexican fishermen regularly sneak into the U.S. to lay illegal nets.
"They get over here in a matter of two minutes and be back in Mexico in a matter of two minutes ... The guys we have caught in the past have flat told us that there are no more fish over there and that is why they are coming over here," Dunks said.
"It’s tragic to see U.S. efforts to rebuild shark populations being undermined by Mexican fishermen fishing illegally in U.S. waters," Elizabeth Griffin Wilson, a member of a National Marine Fisheries Service advisory panel, told msnbc.com.
"Unfortunately, this is not an isolated incident," added Griffin Wilson, who is also a shark expert for the conservation group Oceana. "The U.S. Coast Guard has documented several cases of Mexican fishermen illegally catching sharks in U.S. waters this year."
Those incidents, as reported to the advisory panel last week, included four on South Padre Island last January and February in which 71 sharks were illegally killed.
While not all shark species are threatened, illegal fishing of even abundant species can cause pressure on local populations.
"Sharks are slow growing species that have very few young, thus making it difficult to have sustainable fisheries," Griffin Wilson said.
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