Sorry to hear your sad news.
Fishing reels and equipment often sell well but it may be better to take his old equipment to a bricks and mortar auction house.
If you have rods etc. to sell, they are tricky to post and selling 'collection only' would mean having strangers come to your home.
Most bigger auction houses sell online as well as to bidders in the room so there would be a wide audience.
A quick online search shows that there are a lot of fishing tackle auctions so there would probably be one local to you.
"There are two ways to be fooled. One is to believe what isn't true; the other is to refuse to believe what is true.”
Søren Kierkegaard, Danish philosopher (1813 - 1855)