Does anyone have a good way of determining Rat populations and when to stop trapping them to keep a healthy population?

Not a good way no...most guys stop or move when the catch rate drops significantly.

House counts is a decent indicator.

Best way is hit them hard then give them a break wait a month and hit em again. If you want twice as many next year

as long as you leave half a dozen they will be repopulated by next season. its hard to catch them all unless you just stay till sign is gone.3-4 days and your population will be back to a very healthy breeding stock. Rats travel more then most think. Ive saw several hit on highways a long ways from any kind of water. My dog caught one in town that came out of a storm culvert in mid july That city dog got a quick education!

If you have good rat habitat You will have rats. I don't think you can over harvest rats. You will never catch them all and others will travel a long ways to re populate like Tony mentioned.

Make 2 back to back checks. Then let your sets sit for 2 days then check again. If your still catching rats leave them for another 2 day check. When It's not worth your time pull and move on.

Every lake, pond or slough has different characteristics. There ARE areas you can trap out (almost). And there are areas where you can trap as hard as you want and you'll be right back to 100% the next year, and the next, and the next. For instance, areas that are loon poop bottoms and some sort of bank will be about impossible to trap out. There will always be runs (and rats) in these types of sloughs you'll never find. Counting huts will be of little use in determining rat populations (or harvest rate) in these locations. On the contrary, there are areas with clear water, hard bottom, beach like banks that virtually all the rats are concentrated into huts. I'll say I've over trapped these areas before where there are very very few rats there the following year. I'll hit these locations every 3rd year if I decide to trap them hard.

Another factor in re growth is the surrounding area. Are there rat filled waterways within migration distance...Or is this a lone slough/lake that has little or no chance of any migration? All factors in determining harvest/Re growth rates. Up here in most parts of MN/Wi migration (or that lack there of) is seldom an issue. But that's not the case in many areas across the country, of course.

I agree 100% with Calvin. That untapped population of m'rats is just not everywhere any more. When 99% of the wetlands here are now drained it has an effect. Especially when the remaining waters are subjected to the flood/drought cycles that all that draining has also caused. M'rats need relatively stable water level to thrive in numbers and give them security. Frozen to the bottom and bone dry mid summer ponds won't produce many m'rats no matter how full they look in spring or fall.

Don't know how rats survive when the ice goes to the bottom but they do. One year we had ice all the way to the bottom of the ditches and the sloughs once the ice was gone we took over 1,800 rats. But stable water conditions are the secret to stable rat populations.

Thanks for all the good info really opened my eyes to some possibilities

Trappers in the U.S. are generally interested in merely harvest numbers. Habitat evaluation is a better predictor of the muskrat's ability to set up shop, have a family, build a presence, and establish a community (if you want to think of it like that). Wisconsin in the 50's-80's had registered fur farms where you actually had a biologist visit your farm (marsh) and then you could purchase the estimated number of muskrats from the state for your use (production/harvest). A lot of the research on Horicon Marsh was done to find the most cost effective process/technique to enhance the habitat (THE Food, THE Cover and THE Water) for maxing the fall numbers for harvest. Farming as such. Unfortunately we as trappers have let a lot of that information get put on the back burner in place of sheer picture bragging. Calvin touched on habitat and Tony and Beav touched on immigration and emigration (the source and destination of wildlife dispersion/travel). Just like in ADC work the time of harvest can effect next years production numbers also. So without looking at the big picture of quality of habitat, immigration, and the ever variable yearly weather systems its hard to determine when to stop (or start) harvest activity..... the mike

I trap lots of irrigation lakes so there will be bank den entrances in 10-15 foot of water. Try as you may you will only skim the surface on the population! Baited sets and floats are just a plain waste of time here! Blind sets in feed beds are the most effective. Or the few spots were the bank dens are accessable.