It's also stupid.
Fishing illustration, 1908.
First off, there's no real reason why women should dress any differently from men while fishing. And as fishing is an outdoor activity in which a person is really exposed to the sun, that means a person ought to dress appropriately.
Woman fishing in Washington D.C. tidal basin, 1957.
Which should mean a good broad brimmed hat, long pants and a shirt.
I'm not hugely familiar with boats, so I don't know how hot a person gets out on a boat Because I don't know anything about boats, I'll concede that maybe dressing on a boat is different. Personally, I wouldn't wear shorts on a boat as I hardly ever wear shorts, but I sure would wear a shirt.
Japanese women and children fishing
Not doing so is simply an invitation to skin cancer, or to looking like you are 70 when you are 40. And, yes, I'm aware of sun screen.
Put on a shirt.