What factor contributed significantly to the population rebound of the Double-crested Cormorant since the 1960s and 70s?

Answer

restrictions on pollutants like DDT

The population of the Double-crested Cormorant showed a significant rebound following the implementation of restrictions against environmental pollutants such as DDT.

What factor contributed significantly to the population rebound of the Double-crested Cormorant since the 1960s and 70s?
habitatbirdaquaticdistributioncormorant