How to fish up rare sea creatures more easily?

I need a ton of snapping turtles since I can barley get the radars so I was wondering how to fish up rare sea creatures more often> I realized whale bait says fish up rare sea creatures more often though most use that for more legendaries so idk if it means actual rare sea creatures or not but it seems like it does. Other than that idk any other way to get them more easily lol