Old Dutch words

I have been translating a text written in Amsterdam Dutch in the
year 1680. A friend of mine who speaks Dutch has helped me.
But we still stumble on a couple of words :
<kropgans> : a kind of "gans" = goose
But which one ?
<Besien of St Jans> : possibly a fruit, maybe "strawberries"
<Braezem> : possibly a kind of fish
Does anybody have insight on these words ?

Some other words relate to horse-saddles
and they are about clear, but I'd like confirmation :
<Staert-stuk>
<Voor-stuk>
<Stiegh-beughels>
<Zyden-stukken>

Thanks for any explanation.
Arnaud (and Ivo)