Fish Biologist Henry Quinlan of the Ashland NFWCO and Fish Biologist Nikolas Grueneis of the Iron River NFH pump the stomach of a coaster brook trout.

Close up of the stomach pumping tube inside of a fish.

In an effort to better understand the life history and diets of fish, biologists occasionally need to find out what a fish had for dinner. This happened the other day at the Iron River National Fish Hatchery (NFH). 

Fish Biologist Henry Quinlan of the Ashland National Fish and Wildlife Conservation Office and Fish Biologist Nikolas Grueneis of the Iron River NFH, tested out a method of “pumping a fish stomach” to see just what it had been eating.  The method was being tested for later use at Isle Royale National Park, one of the native locations for coaster brook trout.

Essentially, a small tube is inserted down the throat and into the stomach of a fish.  A small amount of water is pumped into the tube causing the fish to expel any material in their stomach.  The material is expelled onto a screen and is identified using scientific identification keys and a keen eye.  For the purposes of this test, the fish being sampled were fed a small number of surplus production fish from the Hatchery. 

All in all, the test was successful, and will be used on Isle Royale this summer.