What are the trout eating?

What are the trout eating?

You get into your vehicle all excited to spend a day fly fishing for trout. You may have some idea what is hatching that day, or you may not. Even when you get advice from the local fly shop doesn’t mean you will know where to go exactly on the stream or when the hatch will come off.

Armed with a little knowledge can really turn a so-so fishing day into a great fishing day. There are several different ways to approach the problem to help fly fishermen be more successful at catching wild trout in northern Wisonsin trout streams. (Actually, any trout stream, but the focus of my blog is northern Wisconsin.) Let’s break it down into several different scenarios:

  1. Start fishing and as soon as you catch a legal-size trout kill it, clean it, and analyze what is in its stomach. Years ago, we used to do that a lot before catch & release and special regulations. It does work, but you first must catch a decent size, legal trout which can be a challenge at times.
  2. Using a local fly shop’s advice and insights as to what is hatching that day. Depending on what the local fly shop told you, you could start fishing with fly patterns the shop recommended, which is what most fly fishermen probably do. That does require you know where the hatching nymphs prefer to live, hatch and at what time. For example: Hexagenia limbata nymphs prefer the soft mucky bottom sections of a stream. If you are fishing a rocky, fast water section in the daylight hours you will miss the hatch.
  3. Using observation to give you clues as to what the trout may be eating. Meaning, you stand or sit next to the stream and observe any activities in the water or from above the stream for a while. For example, swallows dive bombing and eating emerging insects, or trout bulging or sipping emerging or egg laying insects.
  4. The last method is what I do a lot of the time. I put down my fly rod and grab my small seine to see what aquatic insects are in any given section of the stream. Some give you immediate clues to what will be hatching, and others are for future knowledge as to what are the dominate insects in a stream. For example, in the Spring you may find in your seine a lot of Ephemerella subvaria (Hendrickson) nymphs. If they appear super active and their wing cases are blackish with a white line down the middle of their wing case, they will be emerging very soon.

Seining Aquatic Bugs

First, be sure you know the regulations. Some things require a DNR permit. I seine a section of the bottom of the river or stream flow, analyze what I have in the seine, and then put back into the river the aquatic insects I have collected. Often, I carry my Olympus TG-6 camera and take macro shots of the aquatic insects before returning them to the stream.

Usually, I will use a small plastic cup to place the aquatic insects I collect into and then take close-up photos. Other times I take the photo while the nymphs or larva are on a rock or log, if possible.

Aquatic nymphs in a plastic cup for observation

For seining aquatic insects in the stream, I have two preferred methods:

  1. In the back of my fly fishing vest, I usually carry a Wind River Entomology Gear – Insta-Seine. This seine folds up nicely and when open makes a great net for catching insects in the drift.
  2. A less expensive alternative is to buy from Home Depot a HDX 1 gal. Elastic Top Strainers (2-Pack). You get two white mesh coverings for $2.89. The mesh paint strainers fit easily over your fly fishing net making it a quick seine. It also is easy to stuff in a pocket in your vest.
Wind River Entomology Gear – Insta-Seine

In my opinion. nothing is better than putting your fly rod aside and spending some time exploring the aquatic creatures that live in your favorite trout streams. The knowledge you gain will not only make you a better fly fisherman but also give you a better appreciation for our coldwater resources.

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