Marble Trout of Slovenia
by Tomaz Modic
Marble or marbled trout (Salmo
trutta marmoratus, Cuvier 1817) is a special form of brown
trout that is estimated to be only native to rivers of the
Adriatic river system. Although it can be found in waters
from Italy down to the end of Albania, many Slovenians still
cherish this beautiful creature as THEIR trout! This is more
than unfair to our brown trout (Salmo trutta f. fario) that
is also native in majority of our rivers, but the uniqueness
and mystery that surrounds this beautiful marbled ?subspecies?
is constantly echoing in heads of our ichthyologists and fly
The most known rivers that inhabit
this kind of trout are Soca (pr. Sotcha, or in Italy Isonzo!)
and Idrijca (pr.Ydrytsa) with their tributaries.
Soca is the river after which Slovenians named this trout
SOSKA POSTRV. In direct
translation it means trout from river Soca.
After successful breeding in the recent past we can hope that
this subspecies, form or whatever taxonomic category will
finally prevail among disunioned scientists, will survive.
Personally I do not agree with
a few scientists in the past that classified marble trout
as a species because it is a fact that it can be crossed with
brown trout and the descendants ARE fertile! This is still
is the rule #1of the biology and at least for now I think
we should live it that way. So these two forms of trout must
be the same species if we follow the biological definition
of the species. No matter if it is a form, subspecies or whatever,
I think we all agree that it should and must be preserved.
Let's rather say a word or two about marble trout's unique
The most recent genetic studies
revealed that in fact we could have several different types
of marble trout in Slovenia. The best part is that all of
them can grow to very decent size for every fly fisherman!
Because on the right day, specimens around 35'' can be seen
in those rivers. But like I said, they can be easily seen
- not caught! Carrying genetic heritage of (most probably)
the same ancestor as our brown trout, it is one of the wariest
fish among salmonoids. Although most of the fishermen still
acknowledge only one type of marble trout as the genuine one
and that is now called Zadlascica type. It is named after
Soca's famous tributary where natural barriers seemed to keep
our brown trout (Salmo trutta f. fario) away, providing a
habitat for detached population. This type is olive-brown
or olive- green with that special marbled pattern which sometimes
goes way down to the belly. The colour of the belly is usually
yellowish-white or olive. Variability of shadings is incredible!
They can be so pale that marbled pattern is hardly seen and
on the other hand very dark too. This type has no red spots
on the body! Some years ago all the fish with marbled pattern
with at least one red spot were estimated to be crossings
brown trout. Now they seem to be a type of marble trout as
well. Real crossings just add their share to the confusion.
Usually the biggest specimens
live in deeper water or canyons, well hidden from the fishermen.
Especially in the river Soca. They are territorial and as
they grow larger they start feeding on fish. As with every
decent predator this fish has very sharp teeth. All this makes
fly fishing for big marbles very difficult. Getting deep enough
in fast water is not very easy as we all know and tackle must
be strong enough too. Unfortunately catch & release is
not a very common practice in our country. Now we are able
to keep one marble per day with a size limit over 40cm (somewhere
around 50cm depending on what river we are fishing). So at
least fish under the size limit must be released.
Marble trout has recently become an interesting trademark
of Slovenian fly fishing. Due to the work of devoted domestic
and some foreign scientists from different parts of Europe,
especially from France, it seems it will remain in our streams
and keep bringing fly fishermen from all over the world
to our small and beautiful country.