Guest Blogger: Michael Vorhis, author of ARCHANGEL suspense thriller, OPEN DISTANCE adventure thriller & more to come

In an earlier article I discussed how “aversion” benefits creatures. They needn’t think through threats or their species’ survival strategies in order to achieve sufficient survival rates that the species continues. As long as the threats are not outside the natural order–for example as long as those threats aren’t strange synthesized chemicals to which the creature has no natural aversion but which will nevertheless kill them all–aversion as a risk management scheme serves a species well.

In particular I brought this concept around to trout’s aversion to light. In their inability to invent sunglasses (and their absence of ears on which to hang them), hiding from light saves them from many clawed and toothy critters. They need only retreat to deep water in midday “because I hate that dang light,” and only come back out to the shallows at low light due to the absence of same, and they’re reasonably safe without even knowing what’s out there trying to feast on them–without knowing what a life strategy is.

But still, that run-from-the-bright-stuff instinct is an urge they often disregard. Why? The reason is that there are other competing forces that also shape their behavior. Water temperature far outside their thrivability zones is one–they can opt to remain in water they find more comfortable, visibility be damned. A good example is the sizable trout directly under some of the footbridges across the Merced in Yosemite National Park–they can be seen as clear as my hand, but they remain there because of the depth and coolness of those holes. And trust–that is, presence or absence of other aggressive species, or sometimes even of large specimens of their own kind, is also a factor that can cause trout to remain more visible rather than rub lateral lines with other fish.

One of the most common forces that compels trout to disregard their natural aversion to light is Opportunity. A glut of earthworms in the flow after a large storm can entice them to feed throughout multiple depths of the water column with abandon. They’re getting it while the getting is good. Or take a trico hatch or Salmon Fly hatch…these events see trout, regardless of size and life experience, throwing caution to the wind, exposing their existence and presence to all who care to look by slurping mouthfuls off the water’s surface.

“Opportunity” can come in numerous flavors:

— Surface presence of some prey that represents sizable protein packages in a single gulp–a grasshopper, a cicada, etc.

— Hatches of what we can only assume are really good tasting bugs..again such a tricos or other high-count mayflies, or swarms of midges…in large quantities such that many can be gulped at once.

— Presence of other fish species’ eggs in the flow, regardless of light conditions, or of alevin-stage small fry.

— A “mouthful” creature presenting itself to predation by accident–a crayfish, sculpin, wounded dace, or other desirable meal–especially if it appears trapped against shoreline or structure–again regardless of the immediate strength of the light.

— Other forms abound

Note that “opportunity” is not assessed by a fish on an absolute scale. It’s all relative to alternatives, and to need. A crayfish in relatively shallow water and clear light is far more tempting after a winter of a semi-empty belly than it is while plenty of readily available but safer to pursue food is washing down. The decision whether to disregard the natural aversion to light is still a decision, size of the fish’s brain notwithstanding. It will be risked if the empty belly motivation is there.

Anglers can not only take advantage of light aversion by choosing the water in which to fish at a given hour and by the methods we employ, we can present opportunity for fish to temporarily go against that aversion. Where we suspect fish are holed up in places we can’t seem to get a fly (such as in undercut caverns either too hard to deliver the fly or too certain to end up catching a tree root), we can seek to tempt them out, if only momentarily. Flash on nymphs or on flies intended to represent things that swim can draw attention and coax a bold moment. Motion of the same kinds of flies can signify a wounded or flight-impaired condition of that prey, which factors into the fish’s decision whether or not to risk the well-lit water in a big way. How often does a wounded minnow drift by, after all? Isn’t it worth the risk? Some will think it is.

Since opportunity is weighed not only according to risk but according to alternative opportunities too, fish can consider and reject a chance for one mouthful but decide to settle on a safer one. We leverage this comparative “thought” process by dropping a tiny nymph below a large ostentatious dry. Some reckless individuals will attack the big gulp up top, but most of the smarter ones will weigh that against the miniscule midge 18 inches below and decide they’ll give big danger a miss but that in so doing they owe themselves a little low-risk snack.

In spring after a bleak and hungry winter, or in autumn with the prospect of a severe winter just ahead, trout redouble their interest in feeding. The need is there. And often the light is endurable. Bottom line, the chances of one of them deciding that “it’s worth it, just this once” are higher.

So again, trout behavior can be thought of according to any conceptual framework a person chooses to imagine. I like to think of it in terms of light aversion vs. the temptation of opportunity. It’s an instinct pair that plays each against the other and yet together serves a balance between the needs of sufficient safety and sufficient sustenance…a yin-yang thing…a “saint on one shoulder, devil on the other” paradox, one urge representing wisdom, the other desire. Thinking of trout behavior in these terms has made me a far better angler, and truthfully far more in tune with the cross-critter dynamics of the larger ecosystem of a stream.

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