Stomach Pump

After replacing the 90 degree angle Fish Pimp setup with the regular straight setup, which they ought to call the 180 degree setup, I caught a brown about 14 inches long. Periodically I like to check what the trout have been eating recently so I use a stomach pump. A stomach pump is a suction bulb with a plastic tube attached. It ought to be called a throat pump because it suctions out what is in the trout’s throat, not its stomach. This lets you know what it has most recently eaten. To use a stomach pump, squeeze the bulb, fill the device with water then squeeze some water out to leave the bulb slightly indented so it can pull a suction. Gently push the tube of the stomach pump into the fish’s mouth and barely into the throat. Let go of the indented bulb and check that it forms a suction with the trout’s throat. Pull the device slowly out of its mouth and the throat contents should move up into the tube. Carefully let the fish go in some calm water. If you need to hold the trout in the water a moment for it to gain its strength and balance, go ahead. The insects in the stomach pump can wait. Next, squeeze the bulb to expel the contents onto a surface where you can examine them. This can be your palm, a flat rock or some kind of container. I have in the past prepared small bottles with a 50/50 mixture of glycerol and alcohol in order to store the insects.

This particular day the fish had been eating, most noticeably, bright green caddis pupa. It also had been eating brown-grey scuds, midge pupa and mayfly nymphs. As usual, there was no flying insects that dry flies would be needed to imitate. I had been nymphing with midge pupa and mayfly nymph imititations, which had been working adequately and were consistent with the trout’s recent diet. Nevertheless, I was curious about the larger, easier to see, bright green caddis pupae. I switched to a size 20 green caddis nymph imitation and a size 16 emerging caddis imitation. As you can imagine, I immediately caught another brown, as well as my first white fish of the day.

I usually select the medium size trout (12 to 16 inches) to obtain a throat sample. I do not want to risk taking the time to collect a sample with a large brown. With the large trout I hurry to get a picture and get them right back into the water for release. One thing I have also tried to do is to get a sample from a white fish. My thinking here is to avoid having to sample the trout all together and just sample a big white fish. This doesn’t work. For some reason you can’t get a suction with the white fish and therefore can’t collect a specimen. This is puzzling to me and I keep trying every so often.