U.S. border inspectors in Calexico have seized 529 bladders since February that they believe were destined for China and Hong Kong. The probe began when an inspector spotted about 30 bladders buried in an ice chest.
The bladders came from totoaba fish that live exclusively in Mexico's Sea of Cortez. Also known as Mexican giant bass or giant croaker, the fish can measure up to 7 feet long and weigh more than 200 pounds. The cream-colored, leathery bladders alone measure up to 3 feet.
The fish are captured with gillnets when they migrate in the spring to the shallow waters in the northern Sea of Cortez, authorities said. The gas-filled bladders, which keep the fish buoyant, are removed and taken to stash houses along the border, with the fish carcasses left to rot on gulf shores near the tourist town of San Felipe.
The totoaba has been protected under the Convention on International Trade and Endangered Species since 1976 and was added to the U.S. Endangered Species Act in 1979. Fishing is also prohibited in Mexico.
The totoaba population began to plummet in the 1940s after construction of the Hoover Dam in the U.S. limited the flow of Colorado River water into Mexico. Totoaba spawned near the mouth of the river.
Heavy fishing and inadvertent capture of young fish in shrimp nets also exacerbated the decline.
Just as shark fins are coveted for use in a different soup, the totoaba is desired for its meat but even more for its dried bladders. The organs used in fish maw soup are tasteless but are said to improve skin, blood circulation and fertility.
The soup is also made with bladders of other fish, including sturgeon and bahaba, an endangered fish from the south coast of China.
The seven defendants were charged in four separate complaints with unlawful trade in wildlife.
Jason Xie, 49, of Sacramento was accused of taking delivery of 169 bladders on March 30 in a hotel parking lot in Calexico, about 120 miles east of San Diego. Xie told investigators he was paid $1,500 to $1,800 for each of 100 bladders in February.
Anthony Sanchez Bueno, 34, of Imperial was charged with the same crime after authorities said he drove the 169 bladders across the downtown Calexico border crossing in three coolers. He told investigators he was to be paid $700.
Song Zhen, 73, was accused of storing 214 dried totoaba bladders in his Calexico home.
"These were rooms that didn't have furnishings," U.S. Attorney Laura Duffy said. "In every room, fish bladders were dried out over cardboard and papers."
Xie's attorney, Gerald McFadden, didn't immediately respond to messages seeking comment. Court records didn't list attorneys for Sanchez Bueno or Zhen.
Investigators believe U.S. citizens are transporting the bladders to Los Angeles then to China, said John Reed, a group supervisor for U.S. Immigration and Customs Enforcement's Homeland Security Investigations unit. He said the fish are being caught illegally by the hundreds, suggesting the species could be coming back after years of careful breeding by Mexican researchers.
"It sounds like a substantial amount of them are going from Mexico directly to China but then we've also been seeing a large number being smuggled into the U.S.," Reed said.