What's A Water Skunk? Am I Missing Something?

I was trolling the r/maine subreddit for local goings-on and came across this post that vexed me. It's not the first; this subreddit is a good one for this girl from away to learn some real authentic Mainer things. I'm sure it won't be the last.

Apparently, brag boards like the one below are used for sharing and comparing impressive catch measurements at popular fishing sites. This one was at the Belgrade lakes and includes a 25lb salmon, 20lb pike, and... a 3lb baby Jesus water skunk? There's also a 22lb water skunk logged in the same handwriting. Is this a joke I'm missing or are water skunks a real thing? Someone enlighten me. I'm hungry for knowledge and I don't want to be left out.