Complex sentence: With the sharp decline in the world stocks of cod due to overfishing, other salted and dried white fish are sometimes labeled as "salt cod", so the term has become to some extent a generic name.
Split into simpler sentences: With the sharp decline in the world stocks of cod due to overfishing, other white fish are often used instead. Sometimes these other species are labeled as such, and sometimes still misleadingly called "salt cod", so the term has become to some extent a generic name.