life, but a more gradual increase of the amount of fish
consumed. Using the relationships presented in the
study of KEELEY & GRANT (2001), one would have expected
the trout in our study to be almost entirely piscivorous.
Thus, the large proportion of invertebrate prey in
the food of the trout very likely reflects the limited availability
of suitably sized prey fish in the reservoir in
2000. Although brown trout may swallow prey fish up to
41% of their body length (VEHANEN et al. 1998) mean
values are found in the range of 16% (VEI~ANEN et al.
1998) to 33% (L'ABEE-LuND et al. 1992). In our case,
the predicted mean prey fish size of an average sized
trout (approx. 350 mm in 2000) would lie within the
range of 56 mm to 116 mm, which is not entirely within
the lower length range found for both perch and roach.
Unfortunately, the number of well preserved fish remains
found in our study was not sufficient for a quantitative
analysis of prey fish length.
The three consumption estimates based on the different
temperature scenarios demonstrate the strong effect
of temperature on the relative magnitude of the realised
consumption. While the epilimnic scenario is relatively
unrealistic, it seems reasonable to believe that in fact the
trout experienced a temperature regime somewhere