Is the L in salmon silent?

English is a Germanic and, for the longest time, old English resembled old German. In German, you pronounce every letter of a Word and a lot of German Words are still present in modern day English. That is why a lot of modern English Words require you to pronounce every letter. An example is "hat" which is "hut" in German.

When the vikings and Norms (French) conquered Britain during the middle ages, new Words started to enter the English language. And, it is from these non-Germanic Words that you get these silent letters.

Salmon comes from the old french Word "salmun." The French removed the "l" and changed it to a "u" so the modern french Word is now "saumon." English just kept the "l".

Reference: I speak German and English and know the background of both language (as well as french since all 3 languages are related).