When winter is severe and the waters don’t thaw like they usually do, the ice can actually block oxygen from the water, an act known as winterkill. When this happens, fish suffocate in the water, walleye and bass in particular. It typically only happens in inland lakes, particularly ones that are shallow and filled with weeds and other vegetation. Winterkill can potentially wreak havoc on the entire ecosystem of a given lake, and it could take years to see the population grow to its normal size again.

While winterkill is rough on certain fish, for others, frozen lakes mean a boost for their species. The eggs of some fish are often vulnerable to wind and choppy waters. A good freeze, though, could protect the eggs, which means more fish available for you to catch in the future.

Another thing you’ll notice in the summer after a serious winter is that, if winterkill affected lakes near you, once the ice melts, you’ll probably be catching quite a few smaller fish. This is because mature fish will be working hard to repopulate the lakes.

It’s common for waters to take longer to warm back up after freezing winters. These colder than normal waters can actually slow down the bodily functions of the fish, causing them to be lethargic longer than they usually are. They’ll be more hesitant to chase after faster baits, move from cover, and they’ll eat less in order to keep their bodies warm. If this is the case for you, it might be best to wait until the waters are back up to around 50 degrees before you head out.

With winter storms and deep snow hitting a lot of the northern U.S., anglers will see some changes when it comes to lake conditions and fish behavior in their neck of the woods. Keep today’s tips in mind if this is the case for you and you won’t start your season off on the wrong foot.