 Technicians from Taiwan were contracted by large producers in 1991 to help develop laboratory larvae, but bitter feuds developed between independent shrimpers and the corporations.Local shrimpers charged that corporate methods were damaging the environment and destroying natural stock through destruction of the mangrove breeding swamps.Corporate shrimp farmers then began to move their operations farther inland, leaving local shrimpers to contend with diminished natural supplies on the mosquito-infested coast.