There are a few things that cross over between early season open water fishing and late season ice fishing. In my opinion, the absolute biggest one is that creek mouths are major fish attractors in that late winter/early spring period.
Under the Ice
Ice cover forms a barrier that prevents oxygen exchange in the winter. There is a finite amount down there and it can actually be depleted causing winterkill. Fortunately, that is only an issue in shallow fisheries during years of extended winters. However, creeks that flow into a lake are an important source of oxygen in the winter time. They are attractive areas throughout the season but as the winter wears on, their fish attracting power grows. They also provide nutrients and food for the lower levels of the food chain which, in turn, attracts what we are really after. Creeks and rivers can also be important spawning areas for species like pike, walleye, and smelt so they will often be close by at last ice. You will need to use caution while on the ice in these areas as the current will chew away the ice from underneath. I always recommend bringing a spud, throw rope, and wearing a float suit/ice picks in case someone falls through.
As I mentioned earlier the food chain is already drawn to these areas while they are under ice. The fish are already there and conditions will only improve for them from there. Ice melt increases current flow and brings more nutrients into the water. Increased flow sets the fish up in predictable areas to feed, find those, and they will be readily waiting for food to come to them. Be on the lookout for eddies and current seams. Water clarity often decreases which causes fish to let their guard down a bit. They won’t get as good of a look at what exactly you are throwing and if it is moving and looks like food they are likely going to eat it. The risk is always there for an extreme weather event that muddies the water. Muddy and cold water can, in fact, make things tough but some stain is a good thing. Water temperature can also bump up from a warm rain and that can really turn the bite on. Those fish are there to feed and it can be really special when it’s timed right.
Never pass up a creek mouth or other freshwater input as winter transitions into spring. It is one of the most high-percentage areas to have hungry and predictable fish populations. Don’t be surprised to catch every species a lake has to offer at them either; it attracts all kinds.