Comments on: They can’t be that smart, they eat sticks and leaves

By: KBarton10

KBarton10 — Tue, 10 Feb 2009 02:19:51 +0000

Cutthroat: I’ll keep an eye out for a copy, thanks for the tip.

By: cutthroat stalker

cutthroat stalker — Tue, 10 Feb 2009 01:13:30 +0000

Keith, I know I’m coming at this a bit late, but if you haven’t seen it, you must grab a copy of The Underwater World of Trout, Vol. 2, “Feeding Lies” by Wendell “Ozzie” Ozefovich. It’s interesting to watch fish feed and what/how/where they take food. His narrating voice is a bit hard to listen to at first, but the content is incredible.

-scott c

By: KBarton10

KBarton10 — Tue, 13 Jan 2009 05:14:20 +0000

Feel free to use the post, friend

By: Fly Fishing Frenzy

Fly Fishing Frenzy — Tue, 13 Jan 2009 04:30:52 +0000

Loved the post. Can I use this post for my Blog? Of course I will give the credit where credit is due. My blog is http://www.flyfishingfrenzy.com. let me know. thanks.

Hoss,

By: Eccles

Eccles — Tue, 06 Jan 2009 07:30:13 +0000

A really good post. I love the “..victimized by flatulence and bad breath as well” bit.
I’m not sure I agree entirely about the monocular view. Not solely monocular anyway. A fly in front (and above probably) of them can be resolved very clearly because what each eye sees overlaps, apart from a small blind spot very close. This and the fact that a fish’s eyes stick out from the side of its head and many have grooves running from snout to eye aiding forward vision i think makes them see in a way similar to binocular vision even if the mechanics are not the same. Also it is interesting that the shape of a trout’s pupil (and even more in grayling) is not exactly spherical but a bit cone shaped. I have no idea how that affects vision but there must be an adaptive explanation for two drift feeders to have similar shaped pupils whereas something like a carp seems to have a more rounded pupil.
As for taking lots of twigs and stems, I am sure they do and wouldn’t be surprised if there is some learning going on there. But it would be pretty inefficient to take just as many non-food items as food. Too costly I think.

TU’s comment is a good one. Personalities (or the more cagey “temperaments”) in fish is getting a lot of attention from biologists at the moment.
Absolutely “a great topic, contentious and opinionated”.
Great stuff Keith.

By: KBarton10

KBarton10 — Tue, 06 Jan 2009 05:15:17 +0000

Good point, JPL – the lateral line is part of the answer. There’s an awful lot of blood-rich tissue behind it, and its use is still a partial mystery.

I’ve always assumed it was a “vibration sensor” – but that’s just an opinion, and far from factual.

What’s plain is that a tiny mayfly nymph can tumble down a fast current, and a trout with monocular vision can nail it unerringly. If they weren’t so equipped they’d have starved to death a couple million years ago.

A great topic, contentious and opinionated – and one that should be considered by all anglers.

By: Jean-Paul Lipton

Jean-Paul Lipton — Tue, 06 Jan 2009 04:55:32 +0000

KB, you forget out about the lateral line. That is one sense humans lack, and will never fully comprehend how it is physiologically perceived in fishes. The lateral line is likely the first sense responsible for feeding than sight. Also some other highly evolved fish [ like carp ] have developed barbels, and can taste food without even putting in their mouth. Look at the case of several catfish species who are blind or lack functioning eyes.

I agree with TC, there is way more to fish behavior than most anglers will give credit for. Hell, so much of fish behavior is unknown that even fisheries biologists are in the dark on much of it. It is the arrogance of anglers that type-cast a fish’s behavior and feeding habits. At best we can make an educated guess, and attempt to narrow down the possible scenarios in efforts to improve our success as an angler. Another brilliant nugget brought to light is the fact that no two fish individuals are the same, just like in humans. There may be trends within a school or population, but no two organisms will exhibit the exact same behaviors, under different scenarios, every time. There will be variance. It is just pure, simple physics. Look at chaos theory and equilibrium.

Just like predicting short range weather, we are merely looking for patterns, and try to match them as best as possible, in efforts to increase our success. I know this, because even the roughfisher is not immune from the occasional skunk.

There is no simple answer.

By: KBarton10

KBarton10 — Tue, 06 Jan 2009 02:50:34 +0000

HDW, you’re correct, fish are always on the move – the question becomes at what range do they spot a tidbit, and in that fateful moment they inhale it – what is their visual accuity?

They spot something at distance (unknown) move to intercept, and what is it they see when they decide to eat? They don’t swim around the nymph before inhaling it, they slide over in the current (eyeballing the food maybe with only a single eye) – then decide to eat or not.

With the chow directly in front of them, they cannot see the entire image – as shown above, so it’s likely they committed to the “eat” somewhere between spotting and inhaling prey.

Makes for some interesting cogitation.

By: HDW

HDW — Tue, 06 Jan 2009 02:24:07 +0000

I don’t buy it. While they are do not have binocular vision, they also are not stationary. The side to side motion trout have in a stream is not about just swimming against the current, they are also scanning with their eyes moving to see in totality objects to eat or run from. Regarding twigs and leaves, I’ve seen trout grab floating debris and spit it out once it is determined to be inedible, something people no longer seem to be able to do, i.e. mcnuggets, vending machine burritos, hoho’s…

By: KBarton10

KBarton10 — Tue, 06 Jan 2009 00:34:05 +0000

You’re talking for humans, right?

No self respecting fish would eat that crap, would they?