I'm curious about how the genders of these words relate to the gender of the person. How would one refer to a female fisher, for example? I know that one could use the masculine form because of the pronoun reform, but is there an option to use a feminine form? This question applies to all occupation nouns.
In this case, 'fisker' would be used for both fishermen and fisherwomen. Adding a feminine ending would sound wrong, and may even be taken offence at.
For some other occupations ending in -er, we have the option to add -inne:
skuespiller = male or female actor
skuespillerinne = actress
And for others again, adding -inne is the norm:
keiser = emperor
keiserinne = empress
Then, just to spice things up, some occupations ending in -er can take a -ske ending instead:
sykepleier = male or female nurse
sykepleierske = female nurse (a bit archaic)
For occupations that end in -mann, you have the option to replace that ending with -kvinne, much like in English. It is not required, unless the person you're describing prefers that term, and more commonly done with some words than others.
brannmann = male or female firefighter
brannkvinne = female firefighter, firewoman
I think in this case it's because the previous word ends in "r", and when you have the "rs" combination in Norwegian the "s" gets pronounced as "sh" (assuming you read the sentence as a whole). If you read the words separately, it will probably be pronounced as a regular "s".