A report by the province's Department of Agriculture and Rural Development said 189 km out of the province's 254 km of coast is suffering from severe erosion.
The western coastline of 147 km loses 20-50 m of land a year on average, and the eastern coastline of 107 km, loses 45-50 m, it said.
In the past decade 52 km of dikes on the western coast have been reinforced and upgraded, but the Mekong Delta province has not built embankments in the east.
To Quoc Nam, deputy director of the department, said erosion has been eating away protective forests.
"The waves directly threaten the dikes, tens of thousands of families and hundreds of thousands of hectares of agricultural land."
Le Van Su, deputy chairman of the Ca Mau People's Committee, said a 23-km section of sea dikes from the Doc River to Cai Doi Vam Town has been severely eroded.
Around VND700 billion (US$30.1 million) would be needed to repair it, but the province does not have enough resources and has asked the government, he said.
Ca Mau, on Vietnam’s southern tip, spreads over 5,300 sq.km and is home to around 1.2 million people. It is known for its seafood and aquaculture production, especially prawns, of which it is a major exporter.
The province targets economic growth of 6.5-7 percent a year from 2020 to 2025, and increasing per capita income to VND77 million ($3,300) by 2025, from VND42 million in 2019.