By Bruce Auchly
FWP Region 4 Information Officer 

Rain, rain go away

 

Bruce Auchly

Rainbow trout have large eyes for their body size, helping them to see food underwater even when conditions are not ideal.

Back in third grade, I remember reading a story about a little boy who grew tired of rain ruining his weekends. So he chanted: Rain, rain go away.

And he got his wish.

The sky cleared, the sun came out and in a few weeks it was dreadful; too much heat, everything dried up.

We have been tempted to repeat the little boy's cry this past month as it seemed our soggy weather would never end.

Lawns are out of control, picnics are ruined and rivers run muddy.

The first two are inconveniences, stuff to talk about in the office. But how do fish survive and find food in muddy waters?

Fish are obviously different from you and me, and that's a good thing. Imagine swimming around in 40-degree water now. Brrrr.

Or eating bugs and worms. Excuse me?

What is more appetizing is how fish find food when rivers are high and turbid. Vision? Smell? Taste? How about all three.

You can tell a lot about how well a fish sees by the size of its eyes. Members of the salmonid family – salmon, trout, grayling – all have big eyes for their body size. That means for a fish, they can see well. Walleye, northern pike and bass fall into this big-eye category, too.

While they may not see as well as, say, a major-league baseball player, all they have to do is distinguish the outline or shape of an insect or small fish.

At the other end of the eye chart are those fish with small eyes for their body size and probably poor vision. Here, think pallid and shovelnose sturgeon, or paddlefish.

Those species swim in the lower Missouri and Yellowstone rivers. In the case of the sturgeon they are right on the bottom, where it is dark and muddy. Would make a great movie set for a horror flick.

Yet they find their food, using their senses of smell and taste.

We can smell things that are wonderful or terrible, though our sense of smell is not very acute compared to many mammals and fish. Bears and dogs are well known for their ability to pick up odors we cannot.

But a fish? How do they smell anything underwater? To find out, stick your head in a bucket of water and inhale. Okay, don't.

Odors are just chemicals that float through the air or water. Fish have olfactory senses just like we do. What they don't have is a nose. Their smell sensors are in their skin and, in some cases, fins.

The same with their taste buds. We can only taste things when they land on our tongue. Depending on the species, fish have taste buds on their lips, their skin, or even their barbels (whiskers), if they have any.

Which brings us back to finding food in muddy water. Some fish can taste and smell food even when they can't see it.

Others, like trout that depend more on vision, will either find a bit of clearer water, such as at the mouth of a tributary, or they won't eat.

For a long time, they may not eat. Like up to six months they can go without food.

We would be dead in a matter of weeks without food. But fish can hang on till the rain stops, the sun shines and the water clears.

And that's enough to cheer the heart of any third grader.

 

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