Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_name_90 (tonnage VARCHAR, built VARCHAR, ship VARCHAR)

### Question ###
The ship SSBergensfjord built before 1973 has what tonnage?

### Accurate SQL ###

SELECT tonnage FROM table_name_90 WHERE built < 1973 AND ship = "ssbergensfjord"