Uncommon Knowledge, Part 3

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

Part 2 of this post presented some info on body temperature, the language of motion, migration and spawning. Part 3 discusses species origins and diversity, claims to fame, and some points on diet.

Species Origins, and Man as Proliferation Mule

Rainbow and brown trout may be in the same family (Salmonidae), but they’re different species in different genera. Ancestrally, the family divided into two groups between fifteen and twenty million years ago. Oncorhynchus (from which rainbows spring) became isolated in the North Pacific, and Salmo (the browns faction) in the North Atlantic.

So the natural range of brown trout extends from Iceland to the Atlas mountains in North Africa and from Ireland to the Ural Mountains and the Caspian sea. Non-natives to North America, browns were introduced in the second half of the 19th Century from Germany and the UK. And there are no native brown trout of any kind in the southern hemisphere–all introduced by man. Conversely, rainbows are not native to Europe or the British Isles; they were introduced by man around the same time browns came to North America.

Brown trout have been introduced in Australia, New Zealand (where they’ve so successfully displaced native fish they’re technically an invasive species), both American continents (including far north Canada, Argentina, the Falkland Islands and Chile), Africa (South Africa, Zimbabwe, Malawi, Kenya, Kashmir, Bhutan), and Sri Lanka. And I may have missed some. (Clearly the British felt that ready access to brown trout water was part and parcel to acceptable living in the outlying regions of their empire.)

In North America, in unwitting tribute to the nationalities that brought them to us, brown trout are still known to many of us as “German trout” or “Loch Leven Trout.”

Rainbows have an expansionist resume at least as impressive, in part due to the novelty of their remarkable coloration, but I won’t bother to type it out.

Diversity Within Species

Brown trout (Salmo Trutta) are more genetically complex than human beings. Our chromosome pair count is a mere 23; but at somewhere between 38 and 42, brown trout more than double our claim. Other trout species fall short of the brown in this statistic. The brown trout is so variable, and so adaptable, that attempts have erroneously been made through the years to classify them as many separate species. The vast genetic diversity of brown trout gives rise to at least fifty different sub-species. These sub-species can, and do, interbreed.

Rainbow trout are part of a larger group of trout known as “black-spotted trout.” Other members of this group are the Gila trout, Mexican golden trout and American golden trout. Black-spotted trout all spawn in springtime, and will interbreed if proximity permits. It’s no surprise that goldens and rainbows are closely related, given their geographic proximity.

Notoriety

Other than their color of course, rainbow trout are notorious for leaping. Big and small, they’re acrobats—almost aviators. Their spirit, their heart, is unsurpassed.

Brown trout are pictured large in the mind, but they may be most famous for wariness, especially with respect to light and motion. They’re also known for a vexing persnickety nature when it comes to choosing what flies to take. Hard to fool a big ol’ brown…and again, therein lies the appeal.

Cutthroat trout are well known for the bloody-looking splashes under their chins of course, and for their willingness to spawn with rainbows, but behaviorally they make a name for themselves for their slow careful eye on an insect or offering, inspecting it carefully before deciding whether or not to take.

Brookies can get huge, but they never shake the persona of being the tiny living jewels of headwater streams.

Golden trout are probably most notorious for the hike that’s required to locate them. They may demand the greatest level of commitment of all.

Identity Theft

If it looks, walks, and quacks like a trout, is it a trout? Not always. Lake trout are not trout; they are char, a genus of salmonids similar to, but separate from, trout. Same with brook trout, bull trout, and Dolly Vardens, to name a few North American species. All technically char.

Brook trout are the most trout-like of the char. Once regularly called “squaretails,” they live in pristine waters and readily attack flies of all kinds. They are the only native trout species east of the Rockies.

What about “sea trout”? Are they trout, or just a trout-resembling faker prowling the saltwater? “Sea trout” is the common name usually applied to anadromous (or sea-run) forms of brown trout…of which, again, there are so many strains. Sea trout and freshwater brown trout are the same species.

Although there are males who make the sea run, most sea trout are actually female. They become large, courtesy of using fertile estuaries as grazing grounds, and that makes them capable of producing many more eggs than browns that remain inland. Like sea-run rainbows (i.e. steelhead), sea-run browns don’t normally die after spawning. They can make a number of spawning runs in their lifetime; browns have been known to make up to seven or eight…and some may make more, although death probably overtakes their resume at some point.

Many so-called ‘resident’ brown trout do also undertake migrations. Their travels may not take them as far as the coastal resorts the sea trout crave, but they move up-river and down-river, and sometimes in and out of lakes, at various times during their lives, for spawning, feeding, shelter, and because of temperature changes in the water. They know where to go.

In some cases, these potamodromous migrations don’t extend very far; in other cases they do.

Interesting Facts About Diet

Not only will trout eat nearly any other living thing they can catch and swallow, they’re cannibals–they eat trout eggs and trout fry shamelessly, even of their own species. They will also scavenge carcasses of fish killed in other ways.

Other than evading predators through stealth, trout have one passion: Eating. They spend most of every day doing it, or trying to. In a 24-hour period, nineteen to twenty of those hours is spent foraging, hunting, gobbling critters up. Again, if we’re not getting strikes, the least useful thing to assume is that “they’re not biting,” because that just won’t be the case. In their zeal to feed, they regularly ingest sticks, vegetative matter and other objects, although their sense of sight, taste and touch do a very good job of minimizing what foreign objects go down. Still, they’re at the eating game so much of their time that mistakes are made. A fishing buddy of mine once saw a large rainbow in Alaska repeatedly attack a floating orange peel; must have looked like the mother of all salmon eggs.

The calm before a storm may be one of the best times to catch any fish, including trout. Studies show that trout respond to sudden changes in their environment, like swift barometric pressure changes or the start of a rain storm, by feeding heavily.

Trout start to become “piscivorous” (start to add fish meat to their diet) when they reach approximately 8 inches long, more or less. They’ll still take insects of course, especially if insects are an abundant caloric and protein source in their ecosystem. But they’re no longer limited to those smaller forms of life–they start to develop a taste for small fish and an ability to intercept them. (It may be that their cravings change as they grow, or it may simply be that smaller fish inspected by biologists never seem to have baitfish in their bellies because they can’t catch them…I don’t know. But I suspect that an early disinterest in attacking other small fish serves the species, after which the need for more fresh meat starts to take precedence.) The shift to a more piscivorous nature can be a critical piece of data for us to weigh when we’re deciding whether to lean more heavily on streamer patterns, especially if a given watershed is light on the presence of large aquatic or terrestrial insect species.

Limestone-lined rivers and streams (freestone, or chalk, or other alkaline water) tend to support rich aquatic life–and so food for trout can be plentiful. Acidic waterways are generally less productive; trout either grow more slowly or they migrate–to the sea if they can reach it.

It’s no secret that higher numbers of trout in a given stream or lake tend to mean a smaller average size of fish…but that depends completely on food supply and growing season. High altitude trout have very slim pickings through winter months, so growth is usually meager (a three-year old trout in high country acidic water might still be less than 6″ long)…but denizens of food-rich fisheries can achieve noteworthy average sizes and still exist in large numbers of fish per mile.

This seems so obvious as to be unworthy of mention here…but stand the concept upside down for a moment and look again: If we know there are tons of large fish in a given piece of water, that means food supply is either incredibly plentiful, or incredibly varied, or both. It means we can either try a very wide array of fly patterns, or we must imitate something specific that exists by the shovelful in that water. I used to fish a remote lake on a central Colorado alluvial plain. Trout were huge there; I learned it was because they were mostly gorging themselves on two things: subaquatic snails and small fish. The size and quantity of these trout made it clear that some kind of bounty existed, and so it was only necessary to identify what it was. And I did…to memorable effect.

– – – – –

Part 4 will discuss some info on habitat sharing, smarts, a bit of fishing lore, and hatchery trout.

6 thoughts on “Uncommon Knowledge, Part 3

  1. Mike Cline

    Mike

    A bit of clarification is in order. Alas the curse of the “common name”. “Trout” is a common name that was co-opted when Linnaeus named “Salmo trutta” the brown trout, the first of the salmonids to be scientifically named in 1758. “trutta” being derived from Old English truht “trout,” in part from Old French truite, both from Late Latin tructa, perhaps from Greek troktes “a kind of sea fish,” literally “nibbler,” from trogein “to gnaw.

    “Char” again is a common name of mysterious origin. Some think that the generally dark bodies of the most common species with light markings resembles charred wood. “Char” however is not a scientific distinction. The genus “Salvelinus” was derived from the German “Saibling” which meant “little salmon”. When Linnaeus first named the Arctic char (1758), the name was Salmo alpinus which was later changed to the genus Salvelinus when the morphology distinctions became apparent. Even the Brook Trout was first named Salmo fontinalis (1814). The origins of the three current genus names for the fish we call trout are instructive: Salmo from Latin for “leaper”, Oncorhynchus is Greek for “hooked nose”, and Salvelinus is German for little salmon”. Equally instructive is to see the extensive lists of “common names” used or once used for the most well known species of trout, salmon and char. For example, Arctic Char have also been called Sea trout and Arctic Salmon. Almost every major species has been called trout, char and salmon in some form by someone.

    Although this was a long-winded reply, the essence is simple. Trout are trout, char or salmon. Char are trout, char or salmon. Salmon are trout,char or salmon. It all depends on your preference for “common names” as scientifically–Salmo, Salvelinus and Oncorhynchus have species with all three of these common names.

    Good review Mike.

    Reply
  2. Mike Cline

    Mike

    Another point of clarification and a question. You use the term “black-spotted trouts” and attribute it to a distinct group of trouts. I am curious where that comes from. You mention the Gila, Mexican Golden and American Golden trout as members. Both the Gila and Mexican Golden are separate species, while the “American Golden” is really one of three rainbow trout subspecies in the Kern River Golden trout complex. The question about black-spotted trout stems from the fact that one of the original common names for Westslope Cutthroat was black-spotted trout, but this common name does not get officially associated (Fishbase) with any other trout species that I can tell.

    Reply
    1. Michael Vorhis

      Hi Mike,

      Regarding your tracing of name origins and your statement that “Trout [or Salmon…or Char] are trout, char or salmon,” then getting to the point of my usage in the article and the reason I was making a distinction, are you:
      — Saying that Arctic Char are actually salmon? That they have only a single row of small vomerine teeth?
      — Saying that Brook Trout are actually salmon, with the same vomerine distinction?
      — Saying that Lake Trout are actually salmon, with the same vomerine distinction?
      — Saying that Dolly Vardens are actually salmon, with the same vomerine distinction?
      Or…that some of them are trout? Since as you say the name “char” is apparently not a different category in the Class/Order/Family/Genus/Species scheme, then I think the above fish technically have to be Trout or else Salmon, in the vomerine teeth distinction sense.

      But your point might be that it’s not a useful distinction at all–that it cannot shed any light on the life strategy picture…?

      I came across the “black-spotted trouts” classification (or let’s say grouping) in a scientific paper somewhere, but I’d have to find where…and I confess it could be an old enough work that use of the term could have been abandoned since. I also failed to mention Cutthroats entirely but should have included them in the group, given that they’re more closely related to Rainbows and Goldens and are a North American species rather than a Salmo Trutta. I guess the term “black-spotted trouts” could even come from the culinary world, as I’m now having trouble finding the reference and the paper I’d found that grouped all tese together. If the name is bothersome it’s fine to simply think of the group as North American Trout Species Who Spawn In Springtime. Their life strategy similarities were the main point of my mentioning them as a group at all.

      And actually Cutties are also a subspecies, like Goldens (and like the various flavors of browns). So we’re all dealing mostly with subspecies in our angling lives…and my terminology was off a bit.

      It appears that browns already have a common name for the whole group: “Browns.” Other than the scientific name that no one uses on the stream, “Oncorhynchus Mykiss” (which sounds more like a slur on the personality of Sherlock Holmes’ older brother), I know of no all-encompassing colloquial name for all the Rainbow and Rainbow-esque subspecies. But maybe there is one…if so, I’d add it to the list of knowledge that’s “uncommon,” because I’ve never heard it.

      Anyway if it’s subspecies rather than we’re all really comparing, and salmon excluded it appears we are, then the points are valid but the term needs the preface “sub.”

      Thanks Mike, for the ichthyological annotations/corrections. Joe, as this is a passion of yours I hope you’re getting all this! Sorry if I included some inaccuracies here.

      – Mike

      Reply
      1. Mike Cline

        Mike,
        My real point, not so well put the first time, is that common names are notoriously ambiguous when It comes to distinction. “Trout” and “salmon” are so widely used as common names, in many cases for species that are not Salmonids, that saying something is or isn’t a trout is problematic, even within the Salmonidae family. Add to that, the fact that common names are not subject to taxonomic discipline like scientific names are, and you can see where any given common name can be ambiguous. A case in point, in the genus Arripis, there are four species of fish, the most common of which is Arripis trutta (Eastern Australian Salmon) (Note the specific epitaph: trutta or “trout”). Other species include Arripis georgianus (Australian Herring). Neither of which is a salmon or herring as we know it in North America. Yet, from a common name perspective, they are no less salmon and herring where they are found.

        When in comes to subspecies and common names within Salmonidae, even more ambiguity occurs. There is no doubt that the issue of subspecies within the Rainbow trout species is still unsettled science for the southern parts of the native range, especially in Mexico. But, that said, there are +/- 14 subspecies of Rainbow trout (see https://en.wikipedia.org/wiki/Rainbow_trout for a good overview). Subspecies for the 14 species of Cutthroat trout are a bit more settled but it seems there’s still some discussion over the actual number of subspecies (see https://en.wikipedia.org/wiki/Cutthroat_trout). The other trout where subspecies or lack thereof causes no end of confusion when it comes to common names—the Brown Trout. There is a trend ongoing to refer to the locus of brown trout populations as a Brown Trout Complex instead of individual species or sub-species but no one knows how that will play out.

        Good discussion.

        Reply
        1. Michael Vorhis

          To summarize a few clarifications here that you and I traded offline, you’re pointing out (citing numerous authoritative references of course) that “It is certainly accurate to say a Brook trout is a char, but it would be inaccurate to say a Brook trout is not a trout.” Yes, I do see your point. I had said that Brookies, Dolly Vardens, Arctic Char and Lake Trout were char and not trout, but the fact is that the word “char” is imprecise enough (as are all these terms) that we can’t say only one such name may apply to a given species, subspecies or strain. So I guess the best way for anglers to “classify” is according to behavioral habits, water occupied, etc.

          In short, Science is all well and good as far as it goes, but the “higher authority” is the question of whether we can entice a strike. : )

          Thanks Mike, for the corrections. This 4-part article was submitted back in January, so if Part 4 continues with a few imprecise term usages, I hope everyone will forgive me.

          – Mike

          Reply

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