Evaluation of the temporal development of three introduced populations of brook trout, Salvelinus fontinalis, in Jizerské mountains, Czech Republic

Three populations of brook trout, Salvelinus fontinalis, established in streams and reservoirs in the Jizerské Mountains, Czech Republic, were studied between 1995 and 2006. The maximum age was usually 3+ to 4+, but the age 7+ was also recorded. The inflows of all reservoirs are populated mostly by 0+ to 2+ brook trout, while older specimens live in a lentic environment, migrating to lotic habitats only to spawn. The density of brook trout in streams ranged from 8 to 95 individuals per 100 m2 during spring and summer, while that for reservoirs ranged between 31 and 290 individuals per ha. A strong negative correlation between the size of adult fish and population density in reservoirs was observed. The type of management influenced both density and growth of brook trout. Further introduction of this species in the central European area should be restricted to habitats where native salmonids cannot survive, such as acidified waters

Brown and brook trout populations in the Tatra Mountain lakes (Slovakia, Poland) and contamination by long-range transported pollutants

Fish living in the extreme conditions of the Tatra Mountain lakes were evaluated from a biological point of view as well as an important biomarker of long-range transported pollutants. In Veľke Hincovo pleso and in Morskie Oko, specimens of brown trout (Salmo trutta) of extraordinarily advanced age were found (ages of 18+ and 17+ years, respectively). The capture of a 17+ year-old brown trout in Morskie Oko (2400 g, 540 mm) indicated the presence of the so-called ferox life strategy. The growth of brook trout (Salvelinus fontinalis) was faster than the growth of brown trout in the younger year classes, and while the growth of brook trout stopped after the age of 5+, the growth of brown trout continued. Concentrations of long-range transported pollutants (HCHs, HCB, DDTs, PCBs, PBDEs, and trace metals) in the Tatra Mountain fish were mostly associated with fish age, body weight and length, type of fish tissue, and lake altitude. Persistent organic pollutants (POPs) in fish muscle were dominated by PCBs 138, 153, 180, and p,p'-DDE. Conversely, PBDEs concentrations ranged at substantially lower levels compared to other POPs. Altitude correlated significantly with concentrations of a-HCH, HCB, p,p'-DDT, p,p'-DDE, and with PCBs 28 and 52. The highest contents of trace metals were found in kidney and liver samples, with higher concentrations in Veľke Hincovo pleso than in Morskie Oko. The overall highest trace metal concentration levels were found for Fe, Cu, and Zn. In comparison with other European mountain lakes, the Tatra Mountain lakes are among the more contaminated