The New Zealand fishing company, Sanford, says it is disappointed that a jury has found it guilty of dumping oil waste in American Samoa and falsifying records.
Sanford's fishing vessel San Nikunau was found to have failed to comply with the Federal Act of Pollution from Ships while fishing off American Samoa last year.
Sanford and a former chief engineer were also charged with obstruction of justice.
The company was found guilty of dumping the waste, known as bilge, but not guilty of an obstruction charge.
The employee was found guilty of falsifying documents.
The company faces fines of up to three million US dollars.