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In this study was investigated the genetic variability of breeding and natural populations of Salmo [trutta] marmoratus (marble trout) ten years after the beginning of the recovery and conservation project of the two local races in danger of extinction in Friuli Venezia Giulia (Tagliamento and Isonzo rivers). The wild population was precisely collected in the river Fella (Tagliamento basin). We tested the applying of RAPD-PCR for the individuation of diagnostic markers which discriminate between S [t] marmoratus and S. [t] trutta (brown trout), between Tagliamento and Isonzo marble trout races, and to test also the degree of genetic variability in breedingpopulations. We totally analysed 66 samples (58 marble trout and 8 brown trout). The obtained results confirm not only an expected genetic differentiation between marble and brown trout, but also the existence of a real genetic separation between Tagliamento and Isonzo marble trout. The polymorphic patterns obtained by use of five RAPD-primers on breeding samples, and also intrapopulation similarity diagrams, prove that they have maintained a fair degree of genetic variability, even though inbreeding risk and physiological mortality.

Ecologists traditionally investigate the feeding ecology of vertebrates by visual identification of prey in their scats using a microscope. This analysis, however, presents some pitfalls, such as poor prey identification at genus/species level. DNA barcoding is an alternative to the traditional diet analysis, recently applied to investigate the diet of several vertebrates. It allows the identification of cryptic or not-recognizable prey portions basing their identification on the analysis of conserved DNA fragments. Here, we combined microscope analysis with DNA barcoding to investigate the diet of the Eurasian otter (Lutra lutra) in an area recently recolonized by the species, in the surroundings of Tarvisio, NE Italy. We collected 102 spraints and analysed all of them at microscope. A random subsample (N=50) was then analysed through DNA barcoding, via amplification of the V9 region of the SSU 18S-rDNA 18S gene. Furthermore, we assessed seasonal variation in otter diet and whether otters select certain salmonids size classes, to identify potential conflict with anglers. According to the microscope analysis, otters ate primarily fish (salmonids and European bullhead), secondarily amphibians and, more rarely, crayfish, both annually and seasonally. DNA barcoding analysis confirmed the microscope results, attributing some salmonids sequences to the brown trout (Salmo trutta). The lack of potential prey species reference sequences in the GenBank database hampered us in identifying the other taxa found in the spraints at more informative levels. Consumed salmonids and bullheads were of small size. In particular, otters selected salmonids size class of 100 mm, which is much smaller than the minimum catchable size for angling. Overall, our study confirms DNA barcoding potential for otter diet analyses, highlighting the need of additional markers to improve molecular prey identification and suggesting that otters do not constitute a significant threat to anglers in the area.