Survival Fish Trapping
Now while there are definitely few plants to collect in Winter, some animal and fish may be taken, but ordinarily hunting them will use up too many precious calories, or pose an issue with being gone from your camp or homestead site.
One method and creature which might be in abundance, but something shrugged off by many, is eating carp. It's not a great tasting fish, but some people in Europe and Asia do eat them, and they actually were introduced to the US, and are a terribly invasive species. Removing them from the ecosystem is beneficial to the game fish that are more desireable, so in a SHTF scenario, it might be something that you could do, and feel good about eating.
They're plentiful, especially at certain times of the year, but bottom feeders like catfish. Similarly, they can grow to an enormous size, which makes fishing them a challenge.
One method that might be used to catch some carp, would be a carp trap. It can catch other fish too, and you should throw back other fish that might grow larger, but you can probably catch carp this way with moderate success.
[link to www.livestrong.com
As you'll see, the equipment requirements are minimal, and if you spend a tiny fraction of money, or knew a tiny bit of bushcraft, and were still not too weak from malnourishment, you could fashion these from bought materials or gathered ones.
Here's another link with tips:
[link to www.carp-usa.info
But...yuck how to eat them. Well, while most people simply won't bother, here's a video from someone I respect who likes to eat them by smoking it. All of his videos are great by the way.
In a SHTF scenario, whether that's massive unemployment and trying to live in the wild when homeless, or global economic meltdown, this could be an important means of getting valuable protein that isn't hard to prepare, and provides a lot of calories, and apparently a recipe that some adults and children will eat.