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Study Shows Why Mouse Patterns Are So Effective


If you want to catch bigger fish, you better be using mouse patterns.

According to a study first published in Episodic Predation of Mammals by Stream Fishes in a Boreal River Basin – Ecology of Freshwater Fish, larger fish tend to enjoy the taste of shrews.

Most fisherman have always believed that bigger fish tend to eat bigger meals, but from this study, that focused on the eating habits of rainbow trout and Arctic graying over a 13-year period near Bristol Bay, Alaska, larger fish of both species ate shrews 24% of the time as opposed to other food sources when shrews were overly abundant. 

I believe that most fly fisherman know trout and grayling are very opportunistic feeders. They also know that trout and grayling tend to focus on hatches of insects and aquatic life during certain parts of the year when those bits of food are readily available.

In this study, the only time that trout and graying focused on eating shrews is when the shrew populations were booming every two to three years. This just goes to show that how over abundance focused these fish can be. 


Only the largest of fish of both species seemed to enjoy this shrew smorgasbord. A large part of this fact is that their mouths were big enough to take a shrew down, whereas their smaller brothers and sisters just weren’t big enough.

In other words, the bigger fish knew they could do it so they did it to the extreme, when the opportunity presented itself.

This study tells me is that I should probably be using more mouse patterns on a regular basis. If big trout are ready and willing to eat bigger meals then I want to be in the right place at the right time to make sure that can happen.

What do you think? Have you caught bigger fish using patterns like this study suggests? 

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Study Shows Why Mouse Patterns Are So Effective