Sight Rules Over Smell

I’ve noticed a really strong smell similar to mothballs in a lot of my fly-tying materials (presumably to preserve the item). Presuming trout can smell, could this make a willing trout turn away when it gets a whiff of something not so natural?
Del Spry

Mark Burdass replies: The preservative smell does seem rather off-putting to us, but we breathe air. Trout on the other hand don’t and are also very strong visual feeders and so their main way of identifying potential prey is by sight rather than smell.

In the wild the fish has to attack the prey as quickly as possible to ensure a successful capture so they don’t spend much time in checking out potential food. They usually make a decision about eating it after it’s in their mouth. It is at this point that taste kicks in rather than smell and hopefully too late by then to avoid the hook. This means that in the final milliseconds before the trout takes the fly the odd smell isn’t likely to put it off.

The chemicals that preserve the flies are also generally very insoluble in water, so it isn’t likely to contaminate the surrounding water with an odd smell. Trout do have nostrils on their snout and do have a sense of smell, but the chemicals they can smell have to be soluble in water. This means that as the trout approaches the fly it won’t smell anything odd to put it off. So overall I think it highly unlikely that these chemicals will cause any sort of problem.

Top Tip: Fly Tying Material Storage

Naphthalene crystals act in a similar way to mothballs, making sure any insect crawling or flying into your fly-tying storage area does not last long. Scatter the crystals in the bottom of the container or drawer rather than in the actual bags of materials so the smell doesn’t linger on them.

Reprinted with permission of Trout Fisherman magazine.