Wednesday, April 16, 2008

Guess the trout

How to identify the species? Is it possible to tell by color/shape/general appearence (phenotype) which trout is brown trout (stocked Atlantic lineage, native Adriatic lineage), dentex trout, softmouth trout, marble trout or hybrid?

This question is common in internet forums. In short, the answer in most cases is no. But here is a challenge, try to identify trouts on the picture below. Write your answers in comments, wait for the results of genetic analysis.

All fish were caught in the River Neretva, where we already found several trout species, you can also choose from this list.



  1. First picture (fish) should be soft-muzzle trout.

    Second picture (fish) should be hybrid of brown trout and soft-muzzle trout (S.trutta X S. obtusirostris)

    Third picture (fish) should be brown trout and it looks to like it is a lake form. I expect that this fish will have some of Ad haplotype

    Fourth picture (fish) is again brown trout. I expect that this fish will have AD-N haplotype. It is very similar to the brown trout from RIjeka Crnojevica with AD-RC haplotype(all bigger individuals from R.Crnojevica have the same red spots on body), which is (by mt DNA) closest to AD-N haplotype.

    The last, fifth picture (fish) is by my opinion, without any doubt, Salmo marmoratus, juvenile specimen. It will have mtDNA of S.maramoratus from river Neretva.

  2. Johannes Schöffmann18 April, 2008 09:17

    The first fish seems to be a "kosor" (S.trutta x S.obtusirostris)

    The second fish looks like Adriatic brown trout.

    The third one could belong to the Danube lineage.

    Most interesting are the last two fish. Number four looks like a dentex trout. Number five resembles a marble trout, though I guess it's a dentex trout from the lower course of the Neretva and Hutovo Blato as described by Glamuzina.

  3. Paul Veenvliet19 April, 2008 17:26

    I find it difficult to give names to "just a few trout" without seeing the whole range of variation, especially from a river where I have not been myself. But anyway, here is my guess:

    1: softmouth or softmouth-like hybrid
    2: softmouth-hybrid
    3: Atlantic trout or Atlantic x Danube hatchery hybrid
    4: dentex or dentex-like hybrid
    5: marble trout or marble-like hybrid

    Without genetic data or (at least) a set of measurements of a whole number of similar specimens I don't dare to choose between a genetically pure fish or a very similar looking hybrid, so I leave both options open.

  4. Helmut Belanyecz20 April, 2008 23:06

    I am afraid the question cannot be solved only by pictures.
    Look at the trouts in only one river, how variable they are.
    In Austria there is in fact only one form of brown trout. Two years ago a had caught a trout (45cm) with absolutely no red spot. But also not a trace of a pink ribbon like a "rainbow". I had helt an escaped salmon for possible, but the vomer showed me it was a trout.
    In lake Constance a lot of investigations were made about forma fario and forma lacustris.
    Several pictures of forma lacustris were shown, from only black spots to a shining red ribbon like a rainbow-trout.

    I aggre with you, the first should be a "Weichmaulforelle", but the second also could be an obtusirostris. Is shown often with red spots. The third lokks like a common brown trout.

    But, as i said, I am afrraid, pictures will not be enough to solve this.

    Kind regards
    Helmut Belanyecz

  5. Thank you all for responding.

    Helmut Belanyecz said...

    I am afraid the question cannot be solved only by pictures.

    I couldn't agree more. The problem is that even morphologic and genetic approaches of identifying trout taxa have their limitations and above all - are not cheap, fast or practical. For anglers and for conservation purposes, identifying fish on the site is of extreme importance. We posted the photos above to demonstrate how misleading phenotypes can be.

    Paul Veenvliet said...

    I find it difficult to give names to "just a few trout" without seeing the whole range of variation

    The problem is that the trouts of the River Neretva have such a range of variation (caused by hybridisation of native taxa and by hybridisation with non native brown trout from fish farms) that sometimes even the local anglers disagree on what fish they just caught. In addition, in Bosnia-Herzegovina and neighbouring regions the same common name is sometimes given to different trout taxa. Connecting a common name, a binomial name and a phenotype is indeed a tricky business.

    Preliminary results based on genetic markers (mtDNA and nuclear) say:

    The first fish is a softmouth trout (S. obtusirostris).

    The last fish is a "glavatica" or marble trout (S. marmoratus), but the marmoratus mtDNA haplotype was not found in any of our samples from the Neretva drainage. Therefore the relation with S. marmoratus as known from Slovenia and Northern Italy remains unclear.

    All the other are hybrids (native brown trout × non native brown trout × softmouth trout) with highly similar genotypes and very different phenotypes.

  6. 1. Softmouth (Salmo obtusirostris)
    2. Hibryd - Softmouth x (Neretva) Brown (Salmo obtusirostris)x(Salmo trutta)
    3. (Neretva) Brown (Salmo trutta)
    4. (Neretva) Brown (Salmo trutta)
    5. Hibryd - Softmouth x (Neretva) Brown x Marble
    (Salmo obtusirostris)x(Salmo trutta)x(Salmo marmoratus)

  7. i was wondering if i could find a answer somwhere. maybe u can help me. i caught a trout in the swirt river in palmer m.a and it was a silver gray with a black line down the guess is a bull trout. cross betwwen samlon and laker.

  8. o srry to that last comment about the bull trout if u want to see it for your self heres my aim screen name. kickinassluke1

  9. Bull trout and brown trout may have similar names, but that doesn't mean that they are sister species. They belong to different genera of the same familiy, like for example dogs and foxes. In short, bull trout is not a subject of our research.

  10. I'm not sure if anyone is still checking this but please tell me what the fourth fish is. We have been catching them in a reservoir in Colorado and would really like to know what it is.

  11. As mentioned above, the fourth fish is a hybrid of several Salmo sp. (native and non-native) found in Neretva.